3.1. Determination of the type of penetrations (frontal: in a straight line, in a zigzag, broadened; lateral).
Excavation with a straight shovel excavator produced by lateral and frontal (dead-end)
slaughter. With sidewall vehicles are located at the level of the bottom of the face or above it and have a through passage located parallel to the path of movement of the excavator only at the level of the bottom of the face behind or to the side of the excavator; the scheme of transport routes in this case is a dead end.
The development of recesses by the method of frontal slaughter creates difficult conditions for transport operation. A lot of time is spent turning cars around and reversing them for loading. The average angle of rotation of the excavator platform for loading soil into vehicles, especially when working in narrow faces, can reach 180 °, which increases the cycle time and reduces the productivity of the excavator. Therefore, it is advisable to increase the width of the frontal face to sizes that are 2.5–3.5 times greater than the largest radius of soil cutting by an excavator, and the development should be carried out by moving the excavator along a zigzag or across the pit (Fig. 21).
Widened frontal face improves the conditions for the supply of transport and
allows you to work with the excavator rotation angle within 90 - 110 ° instead of 180 °, which ultimately increases the performance of the excavator and dump trucks working with it.
A widened frontal face should be used only in cases where local conditions do not allow the use of a side face, or
when arranging a ramp into the pit and excavating a pioneer trench. It is also recommended to use a widened frontal face in cases where the parameters of the excavator make it possible to dig a pit in one penetration, in which it is possible to turn dump trucks and reduce the angles of rotation of the excavator for unloading.
When working with a side face, the transport routes are parallel to the axis of movement of the excavator, which makes it possible to supply vehicles for loading without turns and significantly reduce the angle of rotation of the excavator boom during loading. And this, in turn, increases the productivity of the excavator and the vehicles working with it.
In wide excavations (pits) developed by several
penetrations, frontal broadened slaughter, only pioneering
trench, and all further development of the soil in the excavation, as a rule, is carried out by the sidewall method.
Rice. 21. Excavation with a straight shovel excavator:
a) frontal driving with one-sided loading of soil into dump trucks;
b) frontal driving with two-sided loading of soil into dump trucks;
c) frontal driving with the movement of the excavator in a zigzag;
d) widened penetration with the movement of the excavator across the pit.
a) at B £ 1.5R - frontal driving with one-sided loading of the soil into the transport, fig. 21a.
b) at 1.5R£B£1.8R - with two-way supply of vehicles, fig. 21 b.
The maximum width of the frontal penetration will be
B£2 
, (46)
where R op. - the optimal cutting radius, taken equal to
0.8 to 0.9 of the largest cutting radius;
l n - the length of the working movement of the excavator, is taken
equal to 0.75 excavator arm length or 2m.
c) at 2R£B£2.5R - broadened frontal with the movement of the excavator in a zigzag, fig. 21st century
The width of the zigzag frontal penetration along the top is
B z \u003d 2 , (47)
d) at 2.5R£B£3.5R - cross-frontal penetration with double-sided loading into transport, fig. 21 y.
Width of cross-frontal penetration
e) at B³3.5R - after the first frontal penetration, development continues with one or more side penetrations.
The width of each side penetration is, Fig. 22
B b \u003d B 1 + 0.7 R st, (49)
Rice. 22. Development of a pit by side excavation with a straight shovel
Backhoe equipped excavators are used to develop soils below the level of the excavator parking lot and are used in the development of trenches and small shallow pits (for example, under separate foundations). Soil development is carried out by frontal and lateral penetrations. At the same time, frontal penetrations are mainly used in the development of trenches, and side penetrations are used in the development of wide pits. Soil development can be carried out both in a dump and with loading into vehicles. In the latter case, backhoe excavators have an advantage over front shovel excavators, because. it is not required to lower the vehicles into the pits. In addition, backhoes have the ability to dig trenches with vertical walls (in suitable soils). Backhoe excavators during excavation can move along and across the excavation, as well as in a zigzag, Fig. 23
Rice. 23. Excavation with a backhoe excavator:
a) frontal penetration in a straight line; b) frontal driving in a zigzag;
c) frontal widened penetration.
a) B £ 1.6-1.7R - frontal penetration in a straight line
The width of the frontal penetration along the top with one-sided unloading of soil is:
B=b 1 +b 2 = , (50)
where R max is the largest cutting radius, m;
l p - the length of the working movement of the excavator, 2m;
R t - the largest radius of soil unloading into transport;
b k is the width of the vehicles or spoil heap.
With double-sided unloading of soil, m,
B=2b 1 =2(R st - -1) , (51)
Bottom penetration width, m,
B 1 \u003d B - 2mH, (52)
where m is the slope coefficient;
H – face height, m.
b) 1.7R £ В £ 3R - frontal broadened in a zigzag
c) 3R £ B £ 3.5R - frontal broadened transverse penetration.
The width of the frontal broadened transverse penetration is determined by the formula
d) B³3.5 - after the first frontal penetration, they continue to develop one or more side penetrations.
The width of each side penetration is, m,
where R n is the cutting radius along the bottom of the pit.
Dragline.
The recesses are developed by a dragline excavator in several side or in one frontal penetration. The dimensions of the dragline face are determined in the same way as when excavating the soil with a backhoe.
Additionally, a transverse shuttle and a longitudinal shuttle method is used (with the supply of transport along the sole of the face).
During the operation of an excavator equipped with a dragline, the soil is developed below the level of the parking lot and loaded into dump trucks installed at the level of the excavator parking lot or in the face (when working by the shuttle method). Before starting work, the sections of the track along which the dragline moves are leveled by a bulldozer or motor grader. The sites at the parking places of the excavator after moving must have a horizontal surface.
Depending on the width of the excavation and the operating parameters of the excavator, the first penetration is carried out by a frontal face with the excavator moving along the axis of the trench to be torn off or by a broadened frontal face with the excavator moving along a zigzag line. These schemes are mainly used in cases where such a penetration can open a pit to its full width. In other cases, the first penetration is carried out by a narrow frontal face with the installation of an excavator on an axle aligned with the lower edge of the excavation.
After the excavation of the pioneer trench, made during the first excavation of the excavator, the excavation of the soil in the pit is carried out sequentially by sidewalls with loading of the soil into dump trucks installed at the level of the excavator parking lot or in the pit (Fig., m).
The distance of movement of the excavator between parking lots is taken equal to 1/5 of the length of the boom.
When loading soil onto vehicles supplied to the excavator at the same level with it, the average angle of rotation of the excavator should be 70 °. When excavating the ground, the width of the penetrations should be such that the angle of rotation during operation does not exceed 90 °.
Wide recesses are developed in several frontal penetrations or technological methods such as zigzag movement or cross-end penetration, as well as the shuttle operation of an excavator, are used. When constructing wide pits, as well as embankments from the reserve soil, in some cases, lateral penetration is used,
the width of which is about (0.7 - 0.8)R, and the rotation of the excavator boom for unloading is 180 °.
The advantage of sidewalls is the ability to move soil over much greater distances than when working in frontal faces. However, the width of the side faces is less than the front faces, and the depth does not exceed 2/3 of the total depth of cut.
When excavating soil into a dump for a distance exceeding the bucket unloading radius, bulldozers should be used to move the soil from the place of unloading from the bucket to the place of laying in the structure or dumps.
For the development of wide pits, when the condition of the soil and the dimensions of the dragline penetration allow dump trucks to be driven along the bottom of the penetration, it is recommended to use shuttle methods of loading the soil. With these methods, dump trucks are fed into the face along the bottom of the excavation or pit.
With a cross-shuttle scheme, soil is collected alternately from each side of the dump truck. In this case, the bucket is unloaded without stopping the rotation of the boom (without reversing) at the moment it is above the dump truck body.
The cross-shuttle scheme provides a decrease in the angle of rotation of the dragline excavator boom to 10 - 15 °.
With a longitudinal-shuttle scheme, the soil is collected in front of the end
(rear) wall of the body of the dump truck and, having raised the bucket, unload it above the body. When working according to this scheme, the rotary movements of the excavator are virtually absent.
As a result of the use of shuttle methods of loading soil
the height of the bucket and the angle of rotation of the boom are reduced, which significantly reduces the working cycle of the excavator and increases its productivity.
Example:
It is required to determine the type of excavator for the excavation of the pit, select the types of penetrations, calculate the dimensions of the penetrations and their number, which is necessary in order to develop the pit with the following data: V boiler = 4500 m 3, dimensions of the pit on top 40 × 60 m, H boiler = 1.85 m, m open = 0.5.
Since V boiler \u003d 4500 m 3 for the development of the pit, we accept one
bucket excavator equipped with a backhoe with a bucket capacity of 0.5 m 3 brand EO 5015A (Table A.3). According to ENiR § E 2-1-9 tab. 1 (see also the corresponding application tables) the EO 5015A excavator has the following technical characteristics:
- bucket capacity - 0.5 m 3;
The greatest digging depth is 4.5 m;
The largest digging radius is 7.3 m;
The highest unloading height is 3.9 m.
Pit width B \u003d 40m ³ 3.5R \u003d 3.5 7.3 \u003d 25.6.
Consequently, the development of the pit will be carried out by side penetrations.
The first penetration is frontal. Let's determine its width by the formula, substituting the following values R st \u003d 7.3 m, L n \u003d 2 m, R w \u003d 6.0 m, b k \u003d 2.64 m - for MAZ-503 (Table A.7)
B 1 = 
= 10.7 m,
Determine the width of the side penetrations by the formula
In n \u003d R W - mH - - 1+,
where R n \u003d R st - mH - the largest cutting radius at the level of the sole
R n \u003d 7.3-0.5 1.85 \u003d 6.38 m,
V n \u003d 6 - 0.5 - - 1+ \u003d 8.8 m.
Let's determine the number of penetrations for which it is possible to develop a pit:
40 - 10.7 = 29.3 m
29.3: 8.8 = 3.3 (we accept 4 penetrations).
The pit will be developed in 5 penetrations:
I - frontal, 10.7 m wide;
II, III, IV - side full, 8.8 m wide;
V - lateral incomplete, 29.3 wide - (8.8x3) = 2.9 m.
The pit development scheme is shown in fig. 6.8.
Fig.6.8. Excavation scheme
The article reveals the main issues of operation of single-bucket equipment: features of work, arrangement of the working area, selection of a model corresponding to the area being developed. Varieties of single-bucket excavators used for soils from categories I to IV are considered.
Principles and main aspects of the implementation of work in the development of soil with single-bucket excavators.
Excavators are the predominant technicians in carrying out irrigation and drainage and general construction manipulations. occupies 45% of the total mass of excavation work. This type of machine is used in most types of activities: finishing the sides, leveling the bottom of workings, compacting the earth layer, removing loose and frozen layers. Knowing the fundamental points of the development process and taking into account the type of surface being developed will help you choose the right type of equipment in operation.
Device, technical equipment and work process.
A single-bucket excavator is a type of equipment designed to perform a variety of earthwork and general construction manipulations. The production cycle consists of six stages:
- Cutting the soil layer and filling the bucket part.
- Lifting the filled bucket for unhindered bringing to the place of pouring.
- Raising the boom to the unloading platform. Sometimes the rotation of the boom is combined with the lifting of the bucket.
- Dumping of cut rock into dump trucks or dumps.
- Reverse turn to the cutting point.
- Feeding of the bucket part for cutting material.
The movement of single-bucket equipment is carried out through the use of several types of running equipment:
- Caterpillar. This type provides increased cross-country ability, it is used for work in difficult terrain conditions.
- Pneumowheel.
- Walking. Due to the small mass reduces the pressure exerted on the surface, increases stability.
- Rail-walking. Increases maneuverability, reduces pressure on the supporting surface.
Cutting and taking rock takes 15-30% of the working time of the entire production cycle, so the development of soil with bucket-wheel excavators will be significantly higher in terms of productivity. This is due to the continuity of soil sampling by several buckets. However, multi-bucket models have restrictions on the size of the rock being lifted - the size of the lifted inclusions should not exceed 0.2 of the total width of the bucket. In single-bucket technology, there are no such restrictions.
Optional equipment
The base of the single-bucket machine provides the use of four main types of equipment.
In addition to the possibility of using a dragline, grab, forward and backhoes, this construction equipment can be equipped with the following components:
- Bucket rotator. A mechanism that allows you to quickly switch from front shovel to back shovel operation. Most often found on European models: for example, on the Czechoslovak UDS-114 models.
- Slope planner. A separate type of bucket type "backhoe", used for slopes. It provides the movement of the bucket cutting edge at a certain angle. To use the scheduler, an automated control installation is required.
- Ripper. It is used for the destruction of structures, breaking up asphalt or concrete pavement, performing actions with soils from group III with a dragline excavator.
- Strug. An arrow along which a cart with a bucket "runs". Used in the implementation of planning work.
Types of single bucket excavators
By purpose, single-bucket models are divided into three large categories:
- Construction. Universal technique with a full turn and a bucket capacity of 0.15-2 m3. Versatility is ensured by the ability to install interchangeable components for a variety of manipulations. Soil development starting from category III is often carried out by an excavator using replaceable components.
- Career. Semi-universal machines or special shovels with a shortened boom. The bucket capacity of semi-universal models ranges from 2 to 8 m3. They are used for manipulations on difficult terrain, often used in mining.
- Overburden. Machines with a bucket whose capacity exceeds 6 m3. They are operated on "overburden" - cutting off the upper layers of the rock. As a rule, they are equipped with elongated equipment that increases the working radius. Overburden machines do not have the ability to install interchangeable equipment. Overburden construction equipment includes walking draglines with buckets with a capacity of 4 to 80 m3, used for digging trenches, filling dams, and excavating pits.
When possible to operate With various types additional devices single-bucket machines are divided into three types :
- Universal. They have at least 4 types of interchangeable equipment.
- Semi-universal. Machines with a bucket capacity of not more than 4 - 6 m3. On semi-universal models, it is possible to install two or three types of additional modifications.
- Specialized. Bucket capacity over 4 m3. Are issued with one modification of the equipment, without a possibility of change.
General schemes of work
According to the type of organization of ways for the removal of waste material, all soil and excavation work is divided into two large groups:
- Non-transport. When carrying out this scheme, the soil layer is cut off with its laying in an earthen structure, while vehicles are not involved. There are two types of this type of work. With a simple scheme without the participation of additional transport, the cut layers are placed in dumps without subsequent removal. If it is difficult, a temporary dump is used for laying, followed by re-excavation (moving) of the raised rock.
- Transport. After lifting the soil, it is loaded into vehicles and moved to a predetermined location. With a transport scheme, two ways of movement are possible road transport: dead-end or through.
The choice of excavation scheme is carried out taking into account the characteristics of the construction site.
For example, in the laying of oil and gas pipelines, non-transport schemes have an advantage, and in the construction of industrial and residential complexes with the possibility of arranging normal unloading routes, transport ones.
Development is carried out by creating special trenches - penetrations. Sampling is carried out with the device of frontal or side trenches-driving. When carrying out frontal penetration, sampling is carried out on three parts of the active section - two sidewalls and an end slope.
There are two types of side penetrations:
- Closed. Here, the excavator axle is located to the right or left of the excavation section. In this case, three slopes are developed - side sections and end slope.
- Open. In it there is a gradual shift in the direction of the strip with a selection of rock from the sides and the end slope.
Working area and its arrangement
Under the face is meant the working area of single-bucket equipment, which includes the central platform with the placement of an excavator and related vehicles.
The slaughter is equipped taking into account the main parameters:
- The size of the structure being erected and the shape of the required pit.
- Technical indicators of the used excavator. For example, when using tracked vehicles, excavation is acceptable in difficult areas of the terrain where increased cross-country ability is required.
- Technical characteristics of the used road transport. For example, if work is carried out in wetlands, the face should be equipped as close as possible to hard surface to improve vehicle traffic.
The design of the faces with the subsequent sampling of the material consists in the correct determination of the width and depth of the face, the selection of the optimal installation positions of the machines located on the site, the sequential sampling of layers and the equipment for the movement of equipment and related vehicles.
With a small face height, it is worth using a single-bucket model, supplementing it with a bulldozer that rakes up soil material. The bulldozer shifts it to the “excavator working area”, where hilling is carried out, creating a sufficient height of the sides of the working area.
All machines used are installed in such a way as to reduce the turning angle of the boom to a minimum - the turn of the excavator boom takes 70% of the time of the total production cycle.
Improving excavation efficiency
To increase productivity during excavation work, it is required to be guided by certain provisions:
- Calculate the digging radius, taking into account maximum values operated equipment. It should not be higher than 0.7-0.9 of the largest radius of the model used.
- Combine operations to reduce the time spent on the production cycle. For example, to combine the rotation of the platform with the lifting of the bucket part, moving to the place for unloading.
- Reduce the turning angle of the platform by bringing the transport installation site closer to the trench axis. This will help to reduce the loss of working time spent on platform turns.
- Equip unloading ways, providing a quick movement for the removal of the material being lifted.
- Reduce the time spent on the movement of the excavator by planning and equipping the movement paths.
- If possible, avoid moving machines under their own power, preventing premature wear of the running mechanism.
- Select a bucket according to the rock to be cut. For example, use special buckets or bucket containers of at least 1 m3 for loosened rock layers, and use containers from 0.5 to 0.8 m3 for finely crushed rock materials.
- Pay attention to the ratio of load capacity, hauling distance and bucket volume.
Development of soil models with a straight shovel
A straight shovel is a type of bucket container with a fully open top. Rigidly attached to the handle, which is connected to the boom with a hinge. The forward movement of the shovel occurs due to the action of the pressure mechanism, and emptying - by completely opening the bottom.
The front shovel model cuts and lifts in its own direction in front of the bucket, and then smoothly moves forward by the amount of the specified arm travel. The development of the site is carried out until the required profile is formed by creating successive trenches.
Excavation with a straight shovel excavator is carried out by carrying out trenches-driving of two categories:
- Lateral branches with dumping of cut and raised rock into a transport or dump located in the direction of movement of the equipment. The height of the machines in the working area determines the type of side penetration: single-tier with the location of cars on the same level with the excavator, and two-tier - with the placement of machines at different heights.
- Frontal penetrations, during the creation of which the transport for unloading is installed behind the working equipment.
Sidewall is advantageous in reducing the turning angle, convenient supply of vehicles for dumping the selected material, which increases productivity. But, when operating a sidewall, the volume of rock lifted from one area is reduced, leading to an increase in the number of machine movements.
With a frontal type of slaughter, there is a need for the entrance of dump trucks in reverse and the installation of vehicles behind the working equipment, which leads to an increase in the turning angle. This causes a lengthening of the production cycle, an increase in time costs and a decrease in efficiency. At the same time, the frontal face device increases the volume of material to be lifted, reducing the number of movements.
The device of side penetrations is carried out during development in quarries and the formation of recesses with subsequent loading of the waste material onto vehicles.
The scope of the device of frontal faces is somewhat wider:
- The first penetrations in the development of cuts and quarries.
- Work in confined spaces that prevent the arrangement of loading routes.
- Raising rock from rock excavations.
- Carrying out manipulations in the autumn-winter periods on frozen soils.
The implementation of all work is carried out only with the use of the transport scheme. This is due to the fact that the small linear dimensions of the models with the "straight shovel" bucket part do not allow the use of non-transport rock dumping.
Excavation of backhoe models
A backhoe is a bucket container with a "bottom" open part, which has a cutting front edge part. It is attached to the boom with a swivel joint, there is no pressure mechanism. Filling with rock occurs as the container is “pulled back”. Unloading is carried out at the time of lifting with simultaneous overturning.
This variety is used in the development of a site located below the level of the base site. IN backhoe trenches it is advisable to use face or side faces, which allow digging a bed for underground utilities equipment, digging small pits. Rigid fastening of the bucket part allows you to tear off trenches with vertical walls, reducing the risk of shedding of the sides. The time spent on the workflow for such models is 10-15% higher than for excavators with a front shovel.
The foundation on bored piles, made according to the described technology (TISE), can, after minor modifications, be used as a seismic isolation system for individual construction in the corresponding regions with increased seismicity.
During the operation of the end face, the machine with a backhoe moves along the axis of the trench, alternately removing the soil from both sides. To increase productivity, the penetration can be expanded with sidewalls formed when moving away from the main trench. The width of the face is limited only on the basis of the operational requirements of the construction equipment used and the safety standards for excavating this type of rock.
Carrying out work with a dragline excavator or grab
The bucket capacity of the dragline is fixed on an elongated boom. Filling with rock occurs at the moment of pulling the bucket part back to the boom. After filling, the container is finally lifted and transferred to the place of unloading. Emptying is done by loosening the draft ropes.
Dragline excavation is carried out during the construction of large pits or excavations with a depth of up to 16-20m, the construction of a bulk shaft and similar works. The advantages of dragline machines are an impressive boom lowering depth, a working radius of up to 10 m and the ability to operate in spaces with a constant inflow of groundwater with effective development flooded areas.
Dragline work is carried out using end or side trenches. The organization of work and the arrangement of penetrations is similar to the excavation manipulations of backhoe equipment. Most often, the cut layers are unloaded into an organized dump, sometimes into dump trucks with subsequent removal. In certain areas, frontal or side penetrations are available.
Grab - specialized type bucket tank with two wide blades and a rack (or cable) drive system responsible for the forced closing of the blades. It is used for digging narrow and deep areas below the groundwater level. The grapple is attached to an excavator boom to develop spaces with vertical sides. The system of forced opening of the blades holding the raised contents is responsible for emptying the bucket.
The forced lowering of the rack and the immersion of the bucket part into the rock due to the high dead weight makes it possible to develop layers of almost any density with a clamshell bucket, including areas completely hidden under water. The capacity of the bucket part of the grab is 0.35-2.5 m3.
The choice of equipment, taking into account the main features of the development and types of rocks
Single-bucket equipment can be used in all types of rock, including rocky soils and areas with high watering and a constant supply of groundwater.
Excavation with bucket-wheel excavators can be carried out in soils from I to IV categories inclusive. Actually safe operation can be carried out only in sections of I-III categories that do not have large fractions exceeding 0.2 of the width of the ladle part. Manipulations in category IV areas are possible only in homogeneous layers.
Initially, the type of machine is selected after studying all the parameters: the characteristics of the excavation, the category of material being cut, the presence or possible ingress of groundwater, and the need to use interchangeable devices. If several models are suitable for performing manipulations of the same type, it is preferable to perform excavation in trenches and other spaces excavator with a front shovel, dragline and models with a bucket part of the type " backhoe».
The determination of the required volume of the bucket tank is carried out according to the principle of maximum filling with minimal time costs. The maximum load directly depends on the type of material being processed, the complexity of cutting and the depth of the work. The maximum capacity is calculated taking into account the depth of excavation, the type of equipment and the group of rocks.
- Do not install the machine in a working area with a pronounced slope. Only flat areas should be chosen for installation - this will prevent the risk of overturning.
- When performing work on the bucket part with a straight shovel in a face with high walls, it is necessary to remove the resulting peaks in a timely manner.
- On weak and mobile soil areas, the path of movement of equipment is reinforced by shields laid on the ground.
- The development of sections of group IV by an excavator is carried out using additional equipment - the installation of specialized devices will prevent premature wear of the mechanisms.
- If the working area is strongly moistened, production should be stopped until the surface dries.
Before the beginning production process it is necessary to carefully examine the areas for the appearance of cornices and overhangs.
Shovel Excavator Modernization Project to Improve Productivity and Cost Efficiency
1 AREA OF USE
Typical routing developed for the development of excavations with a frontal face using an E0-3322B excavator equipped with a backhoe and loading soil into dump trucks
DEVELOPMENT OF SOILS BY GROUND MACHINES
The technological process of the excavation device includes the development of soil with loading into vehicles or on the edge of the excavation, soil transportation, bottom and slope planning.
The choice of the soil development method and the complex mechanization scheme depends on the volume and timing of the work, the type of soil, the geometric parameters of the earthwork and the conditions for the work.
In complex-mechanized excavation, in addition to the leading earth-moving machine, the set also includes auxiliary machines for soil transportation, leveling, etc.
A single-bucket excavator is used as the leading machine in the development of permanent excavations of considerable depth, pits and trenches of large sizes. For the transportation of soil, dump trucks are most often used, as well as railway transport, conveyor and hydraulic. The number of vehicles and the scheme of their supply to the excavator are assigned from the condition of ensuring the uninterrupted operation of the excavator.
For cleaning the bottom of the excavation, leveling the soil and backfilling the sinuses, as a rule, bulldozers are used.
The technological capabilities of the excavator depend on the type of working equipment, its drive system and the main parameter - bucket capacity. Recommendations for choosing the bucket capacity and other parameters of the excavator, depending on the volume of excavation, are given in the regulatory and reference literature on earthworks.
For excavations of significant volumes, excavators with a large bucket capacity are used. When developing flooded soils, it is preferable to use excavators with "backhoe", "dragline" working equipment. It is advisable to excavate the soil in deep trenches with fastening of vertical walls, as well as in sinking wells, with a clamshell bucket.
Excavators with a hydraulic drive system for the working equipment provide high accuracy of the geometric parameters of the excavation and great opportunities for automating the process of the machine.
The space in which the excavator is located and the excavation of the soil takes place is called the excavator face. The profile of excavator faces and their geometric parameters for the main types of excavator working equipment are shown in Fig.1.
Fig.1. Face profiles of excavators with various working equipment:
a - straight shovel with cable control of working equipment; b - backhoe; V - dragline; g - grab; d - face profile of a straight shovel with a hydraulic control system; e - the same, backhoe; and - grab;
digging radius; - unloading radius; + - digging height; - - digging depth; - unloading height
When designing the production of works, the dimensions of the face are assigned from the conditions for ensuring the maximum productivity of the excavator by reducing the working cycle time. To do this, the height (depth) of the face must ensure the filling of the bucket with a "cap" in one operation of cutting the soil, the angle of rotation for unloading the bucket must be minimal, etc.
The excavation resulting from the sequential development of the soil with the periodic movement of the excavator in the face is called excavation.
Depending on the location of the excavator relative to the face and its movement in the process of excavation, the penetration can be frontal (end) or lateral.
Trenches are developed, as a rule, in one frontal penetration. Excavation is carried out by one or more parallel penetrations. With a significant depth of excavation, it is developed in tiers, gradually deepening until the design contour of the pit is formed (Fig. 2).
Fig.2. Schemes of excavation penetrations with working equipment "straight shovel"
a - frontal (end) penetration; b - the same, with a two-way arrangement of transport; c - broadened frontal penetration with the movement of the excavator "zigzag"; g - cross-end penetration; d - lateral penetration; e - excavation by tiers:
I, II, III, IV - tiers of development;
Depending on the geometric parameters of the excavation and the characteristics of the working equipment of the excavator, the type, size and number of penetrations are assigned.
Single-bucket excavators with "straight shovel" working equipment should be used for excavation of large excavations in the absence of groundwater or their insignificant inflow.
When developing soil with loading into vehicles, a "straight shovel" is the most productive type of working equipment. An excavator with such equipment is placed on the bottom of the face and develops the soil above the parking level. Soil development is usually carried out with loading into vehicles, which can be located on the same level with the excavator or above the bottom of the face.
Depending on the width of the pit, the frontal penetration of the excavator can be straight, zigzag and cross-end. Lateral penetration is used in the development of wide pits. The outlines of the excavation for various penetrations are shown in Fig.2. The width of the frontal penetrations is determined by the formulas:
for frontal rectilinear
;
for zigzag
;
for cross-face
;
for side
Optimum cutting radius of the excavator;
The length of the working movement of the excavator;
Cutting radius at parking level;
The number of transverse movements of the excavator;
- slope factor;
- face height.
To enter the pit, a trench is arranged with a slope of 10-15 ° and a width of up to 3.5 m for one-way traffic and up to 8 m for two-way traffic.
Backhoe and dragline excavators develop excavations (pits, trenches, etc.) of any width and depth not exceeding the maximum cutting depth. Tiered excavation with this type of equipment, as a rule, is not practiced. The excavator is located above the face, which facilitates the development of wet and watered soils.
Soil excavation can be carried out in the direction coinciding with the movement of the excavator - face penetration and perpendicular to the direction of movement - side. In the latter case, the development depth is less than with the end face. Schemes of penetrations and their dimensions are shown in Fig.3.
Fig.3. Schemes of penetrations of an excavator with working equipment "dragline" and "backhoe"
a - frontal penetration; b - broadened frontal; in - cross-end; g - lateral penetration; e - excavation of the pit with two frontal penetrations;
I and II - the sequence of penetrations; 1 - excavator; 2 - dump truck
The soil is developed with loading into transport or into a dump. Dragline works more productively with the movement of soil into a dump or embankment.
Bucket-bucket excavators are continuous earth-moving machines, most effective in the development of excavations of constant cross-section and great length.
Cross-digging excavators are used, as a rule, in the development of quarries, large pits, laying channels, planning slopes of permanent cuts of considerable size, etc.
2 DEVELOPMENT OF SOIL WITH EXCAVATORS
Soil excavation with single-bucket excavators. In industrial and civil construction, excavators with a bucket with a capacity of 0.15 to 2, less often up to 4 m are used. They have a set of interchangeable equipment, including front and back shovels, a dragline and a grab. In addition, the boom included with the dragline and grapple can be equipped with a load hook or wedge.
A straight shovel is an open top bucket with a cutting front edge, rigidly mounted on a handle, which is pivotally connected to the boom of the machine and is pushed forward by means of a pressure mechanism. The bucket is emptied by opening its bottom. This design of a straight shovel provides it with the greatest performance. For loosening the soil, the cutting edge of the bucket is equipped with teeth. This applies to all types of replaceable equipment, but buckets are also available without teeth - with a solid (usually semicircular) cutting edge. When developing soils of groups I and II, the excavator can be equipped with a bucket of increased volume. Soil is being developed when the excavator is at the bottom of the developed face. At a shallow depth, it can tear off the ground even below the standing horizon, for which a ramp is arranged that allows you to install the machine in the bottom of the excavation.
A backhoe is a bucket open at the bottom with a cutting front edge, rigidly mounted on a handle, pivotally connected (without a pressure mechanism) to an arrow. As you pull back, the bucket fills with soil. Then at vertical position the bucket handles are transferred to the place of unloading and unloaded by lifting with simultaneous overturning. The working area is located below the horizon of the machine. Modern models of backhoe excavators have a hydraulic drive that allows the bucket to rotate relative to the handle.
The dragline bucket is hung on ropes on an elongated crane-type boom. The bucket is thrown into the recess at a distance slightly greater than the length of the boom, it is filled with soil by pulling it along the surface to the boom. Then the bucket is lifted to a horizontal position to the boom and by turning the machine is transferred to the place of unloading. The bucket is emptied when the traction rope is loosened. Dragline can develop soil not only highly saturated with moisture, but also under a layer of water.
The grab is a bucket with two or more blades and a cable drive that forcibly closes these blades. The grab is hung on the same boom as the dragline. With the help of a grab, you can develop recesses with vertical walls. When the boom is turned, the bucket moves to the place of unloading and is emptied when the blades are forced open. The grab sinks into the ground only due to its own weight of the bucket. The grab is usually used for the development of soils of low density (groups I and II) and under water. More dense soils must first be loosened.
The performance of a shovel excavator decreases as soil density increases. In addition, it depends on the method of excavation of the soil (when working "on a sweep" productivity increases, when loading onto vehicles it decreases), bucket capacity and constructive solution bucket edges. Excavators with small buckets (up to 0.5 m) are operated by one driver; they are used only for the development of soils of groups I ... III. More powerful excavators are serviced by the driver and his assistant. They can develop (except for the grab) soils of all six groups (the most dense - after preliminary loosening).
The performance of the excavator can be increased by reducing the angle of rotation of the boom and increasing the capacity of the bucket. To do this, it is necessary to fill the bucket with soil as much as possible (with a "cap"), as well as to combine the processes of cutting the soil with turning the boom, etc.
The soil developed by single-bucket excavators is transported by dump trucks, tractors with trailers, trains, hydraulic transport, less often - belt conveyors.
When transporting soil by belt conveyors, the loading link of the conveyor is installed parallel to the axis of the excavator penetration, and the loading bucket-feeder is moved along the loading link as the excavator advances. When moving the excavator to the next stop, the loading link is straightened to a new position. When loading into trains, the rail track should be laid parallel to the axis of the excavator penetration. The schedule for the movement of earth-carrying trains should be made in such a way that the breaks between the departure of the loaded train and the supply of the empty train are minimal, and the train moves as the wagons are loaded. Usually 3-6 buckets of soil are included in a dump truck. Permissible underload should not exceed 10%, overload - 5%.
The mass of soil immersed in one cycle of the excavator is determined by the formula:
,
Geometric bucket capacity, m;
Soil density, t/m;
Loosening coefficient;
Bucket capacity utilization factor (the ratio of the volume of soil in a dense state, developed in one cycle, to the geometric capacity of the bucket).
The number of cars or road trains required to ensure the smooth operation of the excavator is calculated by the formula:
where: - the duration, respectively, of installing the machine under load, loading the machine with an excavator, running the machine in both directions at a given distance, min; at L, km, and average speed, km/h,
The duration, respectively, of setting the car for unloading, unloading the car, technological breaks that occur during the trip (manoeuvres, passing oncoming traffic at the siding, waiting), min.
The load duration of a dump truck varies widely depending on the number of buckets loaded into the body, the type of soil, the average angle of rotation of the machine during loading and the type of excavator:
The number of buckets of soil immersed in the body;
Duration of one excavation cycle, min.
The number of excavator cycles in 1 min when working with loading into vehicles.
The duration of the remaining operations for dump trucks of various carrying capacities is determined on the basis of statistical processing of data from sample time measurements at the facility.
Workplace excavator (i.e. the place where he develops the soil) is called the face. The geometric dimensions and shape of the face depend on the equipment of the excavator and its parameters, the size of the excavation, the types of transport and the adopted soil development scheme. The use of rational methods of work in a correctly selected face ensures maximum efficiency equipment used and high performance at the lowest cost of earthmoving. IN technical specifications excavators of any brand, as a rule, their maximum indicators are given: cutting radii, unloading, unloading height, etc. Working at the maximum parameters for a given machine leads to its rapid wear and, as a result, to a decrease in its productivity. Therefore, for the production of earthworks, optimal operating parameters should be taken, which are 0.9 of the maximum passport data, namely
The optimal height (depth) of the face should be sufficient to fill the excavator bucket in one scoop, it should be equal to the vertical distance from the excavator parking horizon to the level of the pressure shaft, multiplied by a factor of 1.2:
M - the height of the pressure shaft above the level of the parking lot m.
If the height of the face is relatively small (for example, when developing a planning cut), it is advisable to use an excavator together with a bulldozer. The latter develops the soil and moves it to the excavator workplace. Here, the bulldozer piles up the soil, while providing sufficient face height, which makes it possible to effectively use the excavator.
The excavator and vehicles should be located in such a way that the average angle of rotation of the excavator from the place where the bucket is filled to the place where it is unloaded is minimal, since up to 70% of the working time of the excavator cycle is spent on turning the boom.
For a straight shovel, frontal and side faces are distinguished. In the frontal face, the excavator develops the soil in front of itself and ships it to vehicles that are fed to the excavator along the bottom of the face. In this case, the cars approach in reverse alternately from one side of the face, then from the other. Accordingly, the soil is developed either from one or the other side of the penetration axis, while the angle of rotation reaches 140 ° or more, which reduces the performance of the excavator. Frontal slaughter is used in rare cases (when excavating a pioneer trench, entrance ramp, etc.).
In the sidewall, the excavator develops soil on one side of the driving axis and loads it onto vehicles fed on the other side of the driving axis. At the same time, favorable conditions for traffic are provided, and the average turning angle is 70 ... 90 °. Therefore, after pioneer driving, all the soil remaining in the excavation is developed using the longitudinal sidewall method (Fig. 4).
Fig 4. Scheme for determining the penetration of an excavator
1, 2 - excavator parking.
The maximum development width (on one side of the penetration axis) is determined by the leg of a right triangle, the hypotenuse of which is the selected cutting radius, and the second leg is the movement of the excavator between subsequent stops. This value is equal to the difference between the maximum and minimum cutting radii. Based on this, take:
The average angle of rotation of the machine is determined between the direction of the boom when it passes through the center of gravity of the volume of soil being developed on one side (point 0), and the position of the boom at the time of unloading the bucket.
For frontal penetration, it is advisable to take a development width of 2, since in this case the average angle of rotation is the smallest.
Some types of cuts (for example, planning) can be developed by sidewall with traffic on the same level with the excavator. Sometimes, in order to move to development with a side face, it is first necessary to tear off the so-called pioneer trench, which the excavator begins to develop by descending to the bottom of the face along the ramp (Fig. 5, a).
Fig.5. Schemes of penetrations of a single-bucket excavator with a front shovel and transport supply:
a - when driving a pioneer trench and subsequent lateral penetrations:
O.E.1, O.E.2 - excavator parking; O.T.1, O.T.2 - parking lots;
1-3 - the sequence of soil development;
b - with transverse penetrations
If the excavator unloading height is greater than or equal to the sum of the excavation depth, the height of the side of the dump truck or other transport unit, and at the same time 0.5 m is added (per "cap" above the side), the pioneer trench is developed by sidewall when traffic is moving on the day surface at a distance of at least 1 m from the edge of the excavation.
In this case, the width of the penetration will be equal to (see Fig. 5, a), where is the width of the part of the penetration facing towards the transport supply. When determining, one should proceed from the minimum required value to ensure an unhindered turn of the tail section of the machine. This requirement is mandatory, since the unloading radius corresponding to the accepted unloading height must be greater than or equal to plus the slope (driving depth multiplied by the cotangent, where is the slope angle), plus 1 m (safe clearance from the curb to the body) and plus half the width of the transport unit.
With significant dimensions of the recess, it is advisable to develop it with transverse penetrations along the smaller side (Fig. 5, b). This method of development provides the minimum length of the pioneer trench and allows you to organize the most productive ring traffic.
Excavations, the depth of which exceeds the maximum face height for this type of excavator, are developed in several tiers (Fig. 6). At the same time, the lower tier is developed similarly to the upper one, and the cars are fed to the excavator so that the bucket is aimed at the back of the body. The route of the car in this case should be parallel to the axis of the excavator penetration, but directed in the opposite direction.
Fig.6. The scheme for developing a deep pit by successive penetrations (I-V) of a front shovel excavator:
1-5 - the sequence of soil development.
When working with a backhoe, face or side slaughter is also used. When excavating the soil with an end face excavator with a backhoe "towards itself", the excavator moves along the axis of the trench or excavation torn off by it and alternately develops one or the other side of it, depending on which side the next car approaches. In the end face, the average angle of rotation of the machine is 70...90°. The trench can be expanded with parallel sidewalls (Fig. 7). The sidewall is formed during the development of soil on one side of the axis of movement of the excavator. If, during the development of a trench, the soil is piled into a dump on one side of the trench, the axis of penetration is shifted towards the dump, and the width of the development is reduced compared to the maximum possible for end penetration. When excavating into a dump and for transport, vehicles approach the excavator from the side opposite to the dump, and the axis of penetration is shifted relative to the axis of the trench in the direction in which most of the soil is shipped. With side and end faces, dump trucks approach along a route parallel to the axis of movement of the excavator, but towards it, and with end faces they are installed for loading at an angle of 15,..25 ° to the axis of movement of the excavator.
Fig.7. Schemes of penetrations of a backhoe or dragline:
a - for end penetration and subsequent lateral penetrations:
O.E.1 - O.E.Z - excavator parking; O.T.1 - O.T.Z - parking lots;
1-3 - sequence of penetrations of the excavator;
b - with transverse penetrations
It is most expedient to use a backhoe excavator for excavating trenches up to 6 m deep and small pits up to 4 m deep (for example, under the foundations of individual columns).
For end and side penetrations, the organization of the work of the dragline and the backhoe is similar. At the same time, the same ratio of the maximum depth of cut is maintained. The dragline usually moves between successive stops by 1/5 of the length of the boom. Since the dragline bucket is flexibly suspended from the boom, the shuttle operation scheme is very effective for it (Fig. 8). This scheme provides that the dump truck approaches the loading point along the bottom of the face and is loaded by alternate bucket scoops on both sides of the body. The angle of rotation of the excavator during loading according to the longitudinal-shuttle scheme approaches 0 °, and during the transverse shuttle - to 15 ... Thereby total duration the working cycle of the excavator is reduced by 20...26%.
When developing soils of groups I and II, an excavator equipped with a clamshell bucket must be located in such a way relative to the trench that its angle of rotation does not exceed 70 ... 90 °. The grab moves to a new parking lot by 1/4 of the length of the boom.
Fig.8. Shuttle dragline operation schemes.
a - when loading soil into transport, supplied along the bottom of the face;
b - when loading soil into transport supplied at the level of the excavator parking lot and into a temporary dump
Excavators tear off pits and trenches to a depth slightly less than the design one, leaving the so-called shortfall. A shortfall (5 ... 10 cm) is left to avoid damage to the base and to prevent overshooting the soil. To improve the efficiency of excavators, a scraper knife mounted on the excavator bucket is used. This device allows you to mechanize operations for cleaning the bottom of pits and trenches and conduct them with an error of no more than 2 cm, which eliminates the need for manual modifications.
3 EXCAVATOR E0-3322B
EXCAVATOR E0-3322B (Fig. 9) is designed for excavation of soil of groups 1-4, excavations of wells and other local excavations, loading of previously loosened soil of 4-5 groups of frozen soil, as well as bulk materials from a pile and other works in a temperate climate at an ambient temperature of -40 to +40 ° C.
Technical specifications
The highest speed of movement, km / h ..................... 19.66
The greatest overcome rise, hail....................... 22
Rated, power, h.p...............................................75
Nominal flow rate of hydraulic fluid, l/min.......................330
Nominal pressure in the hydraulic system, MPa ........................... 16
The excavator is supplied to consumers equipped with a backhoe with a bucket with a capacity of 0.5 m3.
According to the orders of consumers, the manufacturer can supply the following types interchangeable working bodies. Backhoe equipment: buckets with a capacity of 0.4; 0.63 and 0.2 m; ladle with a profile capacity of e 0.5 m; hydraulic hammer SP-71; static action ripper; extended handle.
Fig.9. Scheme of the excavator E0-3322B
R - radius of rotation of the tail, m + .................................. 2.8
B - width of the turntable (in the cab), m + .................. 2.66
B - cabin height, m .............................................................. 3.14
G - the height of the axis of the five arrows, m ..............................., .............................. 1.96
A - distance from the axis of the heel of the arrow to the axis of rotation, m + ....... 0.45
E - base, m .................................................................................... 2.8
Zh - track, m .................................................................................. 2.04
K - running gear width, m .......................................................... 2.7
L - from the axis of rotation of the excavator to the axis of the rear wheels, m+..++1
M - width when working on outriggers, m + ....................... 1.3
For clamshell equipment: double-jaw clamshell buckets with a capacity of 0.32 m3 and 0.5 m3; clamshell bucket with a capacity of 0.35 / 0.5 m.
For direct digging equipment - buckets with a capacity of 0.57 and 1 m.
Schemes and kinematic parameters of the working area of the E0-3322B excavator with backhoe equipment, clamshell equipment, direct digging equipment and various working bodies are shown in Fig. 10-15.
Fig.10. Scheme of operation of the excavator EO-3322B
| Name (to Fig. 10) | Normal stick with m bucket | Reach stick with m bucket | |||
| 0,5 | 0,63 | 0,2 | 0,4 | 0,2 | |
| R - radius described by the edge of the clod tooth, m | 1,1 | 1,3 | 1,2 | 1 | 1,2 |
| R - the largest digging radius at the parking level, m | 7,5 | 7,6 | 7,5 | 8,2 | 8,2 |
| H - maximum digging depth, m | 4,2 | 4,3 | 4,3 | 5 | 5,2 |
| H - the highest unloading height, m | 4,8 | 4,8 | 4,9 | 5,2 | 5,3 |
| R - unloading radius at the highest unloading height, m | 6,2 | 6,2 | 6,3 | 7,1 | 7,2 |
Fig.11. Scheme of work of the E0-3322B excavator with a backhoe and a ripper tooth
R - the largest digging radius at the level of the parking lot, m + .......... 8.1
H - the maximum allowable depth of slaughter, m .......................... 0.4
R - radius described by the cutting edge of the tooth, m + ............... 0.6
Fig.12. The scheme of fixing the hydraulic hammer SP-71 on the excavator E0-3322B
H- height of hydraulic hammer with wedge, mm++ .......................... 2530
в - hydraulic hammer width, mm .............................................. 640
l- wedge length, mm .............................................................. 500
Fig.13. The scheme of operation of the hydraulic hammer SP-71 on the excavator E0-3322B:
H- the greatest depth of loosening, m .............................. 5.3
R - the smallest loosening radius at the parking level, m 3.5
R - the largest loosening radius at the parking level, m 7.6
Face width (rational), m ..................................... 5
Technological characteristic
Impact energy, J.......................................++++++++2940
Impact frequency (no more), bpm .......................................................... 120
Initial pressure in the pneumatic accumulator, MPa .................. 0.7-0.8
Weight, kg ........................ ... .....................................................750
Fig.14. Scheme of operation of the E0-3322B excavator with clamshell equipment:
R - the largest digging radius at the parking level, m ++ .... 9.3
R- smallest digging radius at the parking level, m++..+.2.36
R - unloading radius at the highest unloading height, m 6.00
H - maximum digging depth, m .............................................. 7.5
H - maximum unloading height, m+....................................6.36
Fig.15. Scheme of work of the E0-3322B excavator with loading equipment:
R - the largest digging radius at the parking level, m + ..... 6.69
R- unloading radius at the highest unloading height, m..+.4.04
H- the highest unloading height, m+ .......................................... 3.2
L- length of the planned section, m +++ .................................... 2.02
Development of excavations with a frontal face using an E0-3322B excavator equipped with a backhoe and loading soil into dump trucks
Depending on the type of soil being developed and the required excavation parameters, the excavator can be used with a normal and extended handle. The extended stick is mounted only on a monoblock boom of an excavator.
Buckets with a capacity of 0.2 are mounted on a normal handle; 0.4; 0.5 or 0.63 m, and for the extended one - buckets with a capacity of 0.2 or 0.4 m.
The largest dimensions of recesses with slopes of various steepness, developed by the E0-3322B excavator, and the amount of movement of the excavator are given in Table 1 (the parameters of the recesses are determined based on technological parameters excavator)
Table 1
| Name | Slope steepness (1:m) | ||||
| 1:1,25 | 1:1 | 1:0,67 | 1:0,5 | 1:0,25 | |
| Normal stick and bucket capacity 0.4 - 0.5 m | |||||
| Excavation parameters, m | |||||
| Depth, N | 3,2/2,3 | 3,2/2,3 | 3,2/2,3 | 3,2/2,3 | 3,2/2,3 |
| Top width, V | 9,0/9,0 | 7,4/9,0 | 5,3/9,0 | 4,2/9,0 | 2,6/9,0 |
| bottom width b | 1,0/3,3 | 1,0/4,4 | 1,0/5,9 | 1,0/6,7 | 1,0/7,8 |
| 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | |
| Normal stick and 0.63 m bucket | |||||
| Excavation parameters, m | |||||
| H | 3,2/2,3 | 3,3/2,3 | 3,3/2,3 | 3,3/2,3 | 3,3/2,3 |
| B | 9,0/9,1 | 7,7/9,1 | 5,5/9,1 | 4,4/9,1 | 2,8/9,1 |
| b | 1,1/3,4 | 1,1/4,5 | 1,1/6,0 | 1,1/6,8 | 1,1/7,9 |
| The amount of movement of the excavator L, m | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 |
| Normal stick and 0.2 m bucket | |||||
| Excavation parameters, m | |||||
| H | 3,2/2,3 | 3,2/2,3 | 3,2/2,3 | 3,2/2,3 | 3,2/2,3 |
| B | 8,5/8,7 | 6,9/8,7 | 4,8/8,7 | 3,7/8,7 | 2,1/8,7 |
| b | 0,5/3,0 | 0,5/4,1 | 0,5/5,6 | 0,5/6,4 | 0,5/7,5 |
| The amount of movement of the excavator L, m | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 | 0,5/2,0 |
| Reach stick and 0.4 m bucket | |||||
| Excavation parameters, m | |||||
| H | 3,9/2,3 | 3,9/2,3 | 3,9/2,3 | 3,9/2,3 | 3,9/2,3 |
| B | 10,7/10,7 | 8,7/10,7 | 6,1/10,7 | 4,8/10,7 | 2,9/10,7 |
| b | 0,9/5,0 | 0,9/6,1 | 0,9/7,6 | 0,9/8,4 | 0,9/9,5 |
| The amount of movement of the excavator L, m | 0,5/2,5 | 0,5/2,5 | 0,5/2,5 | 0,5/2,5 | 0,5/2,5 |
| Reach stick and 0.2 m bucket | |||||
| Excavation parameters, m | |||||
| H | 3,9/2,3 | 3,9/2,3 | 3,9/2,3 | 3,9/2,3 | 3,9/2,3 |
| B | 10,3/10,7 | 8,3/10,7 | 5,7/10,7 | 4,4/10,7 | 2,4/10,7 |
| b | 0,5/5,0 | 0,5/6,1 | 0,5/7,6 | 0,5/8,4 | 0,5/9,5 |
| The amount of movement of the excavator L, m | 0,5/2,5 | 0,5/2,5 | 0,5/2,5 | 0,5/2,5 | 0,5/2,5 |
Note. The numerator shows the parameters of the excavation at the minimum width of the excavation along the bottom, equal to the width of the bucket; in the denominator - at the maximum width of the excavation along the top, which can be developed by an excavator in one pass
The performance of the E0-3322B excavator when excavating and loading soil into dump trucks is shown in Table 2.
table 2
| Performance | |||||
| 0,5 | 0,63 | 0,2 | 0,4 | 0,2 | |
| Technical, m/h, in soil | |||||
| Group II | 78,3 | 100,0 | - | - | 31,2 |
| IV group | 47,2 | - | 19,0 | 37,8 | - |
| Operational, m/h, in soil | |||||
| Group II | 31,3 | 40,0 | - | - | 12,5 |
| IV group | 18,9 | - | 7,6 | 15,1 | - |
4 ORGANIZATION AND TECHNOLOGY OF WORK PERFORMANCE
Basic instructions for the production of work
Prior to the start of earthworks, the surface is preliminarily leveled with a bulldozer, instrumental breakdown of the excavation, and earth-carrying roads are laid.
The soil is developed in the excavation by a frontal face. The slope of the frontal wall of the face is taken equal to 1:0.5;
When excavating the soil, the excavator penetration axis is aligned with the excavation axis.
Dump trucks for loading in reverse are installed in accordance with SNiP at a distance of 1 m from the edge of the trench in such a way that the angle of rotation of the excavator does not exceed 70 °. At the same time, it is taken into account that the excavator unloading radius R(unloading height 2.4 m); unloading into dump trucks ZIL-MMZ-555 is: with a normal handle and buckets with a capacity of 0.5 and 0.63 m - 6.6 m; with a normal handle and bucket 0.2 m - 6.7 m; with an extended handle and a bucket with a capacity of 0.4 m - 7.7 m; with long stick and bucket 0.2 m -7.6 m.
The slopes of the side walls of the excavations developed by the excavator must be taken in accordance with the SNiP, depending on the type of soil and the depth of the excavation.
The technological scheme for the development of soil with an E0-3322B excavator is shown in Fig. 16.
Fig.16. The scheme of soil development in excavations by the E0-3322B excavator:
1 - excavator EO-3322B; 2 - landmarks; 3 - car - dump truck ZIL-MMZ 555
5 QUALITY REQUIREMENTS
Scheme of operational quality control
Development of pits with an excavator
Composition of operations and controls
| Stages of work | Controlled Operations | Control (method, scope) | Documentation |
| Preparatory work | Check: Implementation of the vertical planning of the surface of the construction site (if necessary); Breakdown of the axes of the structure and the boundaries of the pit. |
Visual Measuring |
General work log |
| Mechanized excavation | Control: Deviations of the marks of the bottom of the pit from the design ones; Type and characteristics of the exposed soil of natural bases; The dimensions of the pit in terms of; The steepness of slopes. |
Measuring, measurement points are set randomly; to the received area 1020 measurements Measuring |
General work log |
Acceptance of completed |
Check: The geometric dimensions of the pit; Marks and slopes of the bottom of the pit; The steepness of the slopes of the pit; The quality of the base soils (if necessary). |
Measuring Technical inspection of the entire surface of the base |
Certificate of inspection of hidden works |
| Control and measuring tool: level, tape measure, theodolite, template. | |||
Operational control is carried out by: foreman (foreman), surveyor - in the process of work Acceptance control is carried out by: employees of the quality service, foreman (foreman), representatives of the technical supervision of the customer. |
Technical requirements
On the device of the bases under the structure, an act of examination of hidden works should be drawn up.
Not allowed:
erosion, softening, loosening or freezing of the top layer of the base soil with a thickness of more than 3 cm.
6 ENVIRONMENT AND SAFETY REGULATIONS
When working on excavators, one should be guided by SNiP 12-04-2002 "Labor safety in construction. Part 2. Construction production"and SNiP 12-03-2001" Labor safety in construction. Part 1. General requirements", as well as the rules set forth in the operating instructions for the excavator. In the face, the excavator must be installed on a flat, planned area. Work on slopes is not allowed.
When working with a front shovel in a high face, it is necessary to remove the peaks and large stones located on top, because when the soil crumbles, they can damage the excavator and cause an accident.
It is forbidden to find people and perform any other work in the excavator's coverage area; the path of movement of the excavator within the construction site must be planned in advance, and on weak soils reinforced with inventory boards.
Earthworks in the area of underground utilities (gas pipelines, electric cables, etc.) are allowed only with the written permission of the organization responsible for the operation of these communications. The permit must be accompanied by a plan (diagram) indicating the location and depth of the communications. Prior to the start of work, it is necessary to install signs indicating the location of underground utilities.
When approaching underground utilities, excavation work should be carried out under the supervision of a foreman or foreman, and in the immediate vicinity of the gas pipeline and live cables, in addition, under the supervision of gas and electrical workers.
Excavation in the immediate vicinity of existing underground utilities is allowed only manually with shovels; the use of crowbars, picks and pneumatic machines is prohibited.
Loading of soil into dump trucks with an excavator should be carried out from the side of the rear or side of the dump truck. It is forbidden to keep people between the excavator and the vehicle during loading.
During breaks in work, the excavator bucket must be lowered to the ground. After finishing work, the excavator operator must not only firmly install the bucket, but also slow down the excavator.
Within the collapse prism, the storage of materials, the movement and installation of construction machines and vehicles, as well as the installation of communication line poles are prohibited.
Work in trenches and pits exposed to moisture after their full or partial opening is allowed if precautions are taken against soil collapse. To do this, the foreman or foreman must carefully examine the condition of the slopes before the start of each shift; it is necessary to bring down the soil in places where overhangs and cracks are found at the edges and on the slopes; temporarily stop work until the soil dries; reduce the steepness of the slopes in the area where the work is urgent.
INSTRUCTIONS
on labor protection and safety for drivers of single-bucket caterpillar and pneumatic wheel excavators
I. General requirements
1. Persons not younger than 18 years of age who have completed a special training course and received certificates for the right to operate an excavator of a certain model are allowed to drive excavators.
2. Each excavator is assigned to a specific service personnel. One of the machinists is appointed senior (foreman).
3. Regardless of the training course, all service personnel must undergo safety training in accordance with the working conditions.
4. Personnel servicing the excavator must be in overalls and have all the appropriate protective equipment. Without this, it is forbidden to work on an excavator.
5. Before the start of the shift, the driver must receive precise instructions on the working conditions in the order in which the task given to him is performed.
6. Maintenance personnel have no right to start working on the excavator without making sure that it is in full working order.
7. All rotating parts - gears, chain and belt drives, flywheels, etc. - must be protected by casings. Starting the excavator with the covers removed is prohibited.
8. Starting the engine and mechanisms is allowed only after the signal is given by the driver.
9. During the operation of the excavator, it is strictly forbidden for everyone, except for the driver, to be on the turntable. It is not allowed to have foreign objects on the turntable.
10: It is necessary to ensure that in all keyed, bolted and wedge connections of the critical parts of the excavator, the possibility of their spontaneous separation is completely excluded.
11. Fill the engine with fuel and lubricant only in natural light and only in case of emergency at night with electric lighting (from the mains or battery).
12. During refueling, it is forbidden to smoke, use matches, kerosene lanterns and other sources of open fire. After refueling, all parts spilled with fuel or grease should be wiped dry, and spilled fuel should be thoroughly covered with sand.
13. Do not use open fire to heat the engine. When starting a cold engine, pour into the radiator hot water, and in the crankcase - heated oil.
14. Fuel that has ignited near the machine must not be extinguished with water. For this purpose, it is necessary to use a fire extinguisher, which must be in the cab of the excavator, as well as sand, tarpaulin, etc.
15. The driver handing over the shift is obliged to warn his shifter about all malfunctions of the excavator discovered by him during operation, and also to make entries about this in the journal.
II. Excavator workplace
1. The site where the excavator is installed must be well planned, lit and provide good review work front. The excavator must be secured to prevent its spontaneous movement.
2. The distance from the outer edge of the caterpillar to the edge of the trench and the pit is determined by the calculation for the stability of the slopes, but it must be at least 1 m.
3. The face for a front shovel should be a wall rising above the surface of the parking lot of the excavator with an inclination at the angle of repose of the soil away from the excavator. Vertical walls of the face are allowed only in dense soils.
4. For backhoes and draglines, the face should be a surface below the excavator parking surface, sloped at an angle of repose away from the excavator.
5. For a front shovel, the height of the face should not exceed the maximum digging height of the bucket. At the same time, the formation of overhangs (visors) that can collapse and fall asleep to people serving the excavator should not be allowed.
6. For backhoe and dragline, the height of the bottomhole should not exceed the maximum dig depth for this installation of the excavator.
7. The driver is obliged to monitor the condition of the face and, if there is a danger that it will collapse, immediately take the excavator to a safe place and inform the work manager about this. Excavator escape routes must be kept clear at all times.
III. Safety precautions during operation of the excavator
1. On each excavator, the rules for operating, caring for equipment and a diagram of starting devices must be posted.
2. When starting the diesel engine, do not take the handle in the girth, all fingers should be on one side of the handle. Do not start an overheated starting motor.
3. To avoid burns, hands should not touch the exhaust pipe when starting and running the starting engine and diesel engine. Care should also be taken when opening the radiator cap and draining hot water from it.
4. It is unacceptable to troubleshoot while the engine is running.
5. It is forbidden to bring objects larger than 1.5 m into the excavator cab, regardless of what material they are made of, as well as store gasoline, kerosene and other flammable substances in the cab.
6. During a thunderstorm, work in or near the excavator, as well as in the area cable network, is prohibited.
7. You can not open a barrel of gasoline by hitting the cork with metal objects.
8. In order to avoid accidents in the event of a break in the hoisting rope or in the event of an accident in the working mechanism during the operation of the excavator, it is forbidden for anyone to be within a radius equal to the length of its boom plus 5 m, but not closer than 15 m from it.
a) change the reach of the boom when the bucket is full (with the exception of shovels that do not have a pressure mechanism);
b) adjust the brakes when lifting the bucket;
c) pull with the help of an arrow the load located on the side.
10. In the event of a break, regardless of its duration, the excavator boom should be moved away from the face, and the bucket should be lowered to the ground.
11. Cleaning, lubrication and repair of the excavator can only be done after it has stopped. In this case, the engine must be turned off, and all moving and running parts of the excavator must be locked.
12. Cleaning of the bucket and inspection of the head blocks of the boom are carried out with the knowledge of the driver during the stop of the excavator with the bucket lowered to the ground.
13. If underground cables, water and sewer pipes, as well as gas pipelines are located in the working area of the excavator, then the maintenance personnel must be specially instructed on precautionary measures and work under the supervision of technical supervision representatives.
14. Work under the wires of existing power lines of any voltage is prohibited.
15. In the security zone of a power transmission line, it is possible to work only by agreement with the operating organization if the horizontal distance between the extreme points of the mechanism at the maximum outreach of the working body of the load and the nearest wire of the power line will be at a voltage of 1 kW - 1.5 m; up to 20 kW - 2 m; 35 - 110 kW-4m; 154 kW - 5m; 220 kW - 6 m and 330-500 kW - 9 m.
16. Soil should be loaded onto the vehicle from the side of its rear or side board. It is strictly forbidden to carry the bucket over people and the driver's cab. During loading, the driver must leave the cab if it does not have an armored shield.
17. When unloading, the bucket should be lowered as low as possible so as not to damage the vehicles. It is impossible to allow oversized loading of the body and uneven distribution of soil in it.
18. An alarm system must be linked between the driver of the excavator and the maintenance personnel of the vehicles. During loading onto vehicles, workers are prohibited from being in them.
19. If blasting is carried out in the face, the excavator must be moved to a safe distance and turned to the explosion site with the back of the cab.
20. Additional requirements when operating an excavator with a straight or reverse shovel:
a) when filling the bucket, it must not be allowed to penetrate excessively into the ground. Braking at the end of the turn of the boom with a filled bucket should be done smoothly, without sharp shocks;
b) when lifting the bucket of a straight shovel, one should not allow its block to rest against the boom block;
c) when lowering, the boom or bucket should not hit the frame or caterpillar, and the bucket should also not hit the ground;
d) when digging in heavy soils, the handle cannot be extended to failure;
e) obstacles in the face, which can cause a significant overload of the bucket or damage to it, should be bypassed by turning the boom;
f) when developing the first trench, it is necessary to ensure that when turning the bucket for unloading, the tail of the excavator does not touch the side wall of the face;
g) during excavation, it is necessary to monitor the correct winding of the ropes on the winch drum so that they do not cross on the drum. The winding ropes must not be guided by hand.
21. When working with a dragline or grab:
a) if an obstacle is encountered during the filling of the bucket, it must be bypassed by raising the bucket. It is forbidden to make sharp jerks with a bucket;
b) after filling the bucket, it should be lifted immediately.
22. When operating excavators equipped with a wedge:
a) the area of operation of the excavator from the place of work of the wedge-woman must be fenced with warning signs within a radius of 40 m;
b) only excavators who have undergone special safety training are allowed to work on an excavator equipped with a wedge;
c) before starting work, it is necessary to carefully check the fastening of the ropes. The rope must be of such length that after the impact of the wedge-woman on the sole of the face, at least two turns of the rope remain on the winch drum;
d) work with a wedge is allowed when the boom is tilted at least 60 ° to the horizon;
e) when inspecting and repairing, as well as replacing the rope, the wedge-woman must be on the ground.
IV. Excavator Travel Safety
1. Independent lowering and lifting of excavators is carried out only at an angle not exceeding that specified in the table. Descent and ascent at an angle greater than indicated in the table must be carried out using a tractor or winch in the presence of a mechanic, foreman or foreman.
2. The path along which the excavator will move must be leveled and planned in advance, and on weak soils reinforced with shields or flooring from boards, beams or sleepers. For structures such as bridges, pipelines, embankments, etc., you must first check the strength and obtain permission from relevant organization to move an excavator over them.
3. While the excavator is moving, the boom must be installed strictly in the direction of travel, and the bucket should be raised above the ground by 0.5-0.7 m, counting from the lower edge of the bucket. The movement of the excavator with a loaded bucket is prohibited.
4. The movement of the excavator near and under power lines should be carried out under the supervision of an engineering and technical worker.
7 TECHNICAL AND ECONOMIC INDICATORS
Technical and economic indicators in the development of excavation and loading of soil into dump trucks are given in Table 3.
Table 3
| Name | Normal arm with bucket capacity, m | Extended arm with bucket capacity, m | |||
| 0,5 | 0,63 | 0,2 | 0,4 | 0,2 | |
| Labor costs per 100 m, man-hour, in soil | |||||
| Group II | 3,2 | 2,5 | - | - | 8,0 |
| IV group | 5,3 | - | 13,1 | 6,6 | - |
| The cost of machine time per 100m, mach - hour, in soils | |||||
| Group II | 3,2 | 2,5 | - | - | 8,0 |
| IV group | 5,3 | - | 13,1 | 6,6 | - |
| Production for 1 person-day. m, in soil | |||||
| Group II | 256,6 | 328,0 | - | - | 102,5 |
| IV group | 155,0 | - | 62,6 | 124,0 | - |
10. Technology of soil development by excavators with working equipment "straight shovel"
Front shovel excavators are excavating soil above the level of their parking lot. At the same time, the bucket moves from the bottom up and away from the excavator. With a straight shovel, soil is developed more often with loading into vehicles.
The bucket of a straight shovel is filled with soil when moving up along the slope of the face (Fig. 5.4). The cutting radius of a straight shovel - the distance from the bucket teeth to the excavator's axis of rotation - is a variable in height.
The most characteristic cutting radii are the largest and at the standing level. Each of them has two values: the minimum R p min and R 0 min when the handle is retracted to failure, back and maximum R p max and R omax when pushing the handle forward with a pressure mechanism. Their value also depends on the angle of the boom. The largest cutting radius of the excavator is measured at the level of the pressure shaft.
Rice. 5.4. Working equipment for earthworks and operating parameters of straight shovels.
Rice. 5.5. Slaughter scheme and main operating parameters of hydraulic excavators
with working equipment straight shovel: maximum possible digging height; the largest and smallest digging (cutting) radii at the level of the excavator parking R p max and R p min ; unloading radius R in; unloading height H in.
The minimum cutting radius at the level of standing straight shovel is determined by the distance from the axis of the excavator to the point where the bucket teeth touch the ground, which is located approximately on the vertical passing through the axis of the pressure shaft.
The face height of a straight shovel has three values: minimum, normal, maximum.
The minimum bottomhole height corresponds to the excavation depth at which the bucket is filled in one scoop. On light soils with low cutting resistance, the chip thickness can be large, which allows to reduce the set length. In heavy soils, due to the small thickness of the chips, the minimum face height will be greater.
On average, the normal face height of a straight shovel is equal to the height of the pressure shaft h nv above the level of the excavator.
The maximum face height corresponds to the highest possible height of the bucket above the level of the excavator. With a face height exceeding the maximum cutting height of the soil by an excavator, a so-called peak is formed from above, especially in cohesive and wet soils. When the visor collapses, damage to mechanisms and maintenance personnel can be caused.
The largest unloading radius R in max, as well as the cutting radius, is measured at the position of the bucket teeth at the level of the axis of the pressure shaft (Fig. 5.5) . The same position corresponds to the normal unloading height H in , measured from the level of the excavator to the lower edge of the open, freely hanging bucket bottom. With the bucket raised to the maximum, there will be the largest unloading height R in max and the unloading radius corresponding to it R V .
Soil development EO direct shovel produce frontal and side slaughter.
With frontal slaughter, the excavator develops soil in one pass in front of and to the side of the axis of travel, which is combined with the axis of the excavation. The developed soil is loaded into vehicles located at the level of the bottom of the face behind the excavator. At this method development, the angle of rotation of the EO to the vehicle reaches 140 ... 180 0 , which significantly reduces the performance of the excavator. Therefore, frontal slaughter is taken extremely rarely, mainly when arranging an entrance ramp into a pit or when developing the first (pioneer) penetration.
During lateral development, the excavator scoops soil mainly to the side of the axis along the excavator, which is unloaded into vehicles placed either at the level of the excavator, or slightly higher on the ledge, and the axis of movement of the vehicles is parallel to the axis of the excavator. This type of development is possible with a wide excavation carried out in two or more passes.
Sidewall development is preferable, as it provides Better conditions for access and loading of vehicles, the angle of rotation of the excavator decreases, which contributes to more efficient operation of the machines.
The width of the excavation on top with a frontal face can vary significantly
V l \u003d (0.8 ... 1.9) R p.
With a face width on top (0.8 ... 1.5) R R trackless vehicles (dump trucks) feed from one side behind the excavator , and with a width on top (1.5 ... 1.9) R R - on both sides of the excavator alternately, which eliminates the downtime of the excavator when changing transport units and reduces the average value of the angle of rotation. In some cases, to reduce the idle passages of the excavator and facilitate the maneuvering of dump trucks, it is possible to apply a widened up to 2.5 R R frontal face with the movement of the excavator in a zigzag.
With an excavation width exceeding 2R p, the development of the soil is carried out with the side face of straight shovels, when the excavator scoops the soil mainly on one side of the axis of movement and partially in front of itself .
From one parking lot, the excavator can select the soil in front of it for a length no more than the length of the pressure stroke of the handle - l n .
Excavator step
Ш \u003d (0.75 ... 0.08) l n.
To reduce shortfalls along the slope of the ledge, the excavator is not allowed to operate with the limiting values of the cutting radii. Then, taking into account the step length of the excavator, the distance from the axis of the excavator to the edge of the face slope cannot be more:
It is not advisable to develop the soil in the direction of vehicles with a turn in plan at an angle of more than 45 °, since at a larger angle it is difficult to set the soil, which is moved into the goaf, beyond the cutting radius of the excavator.
Maximum belt width for lateral development
B l \u003d B 1 + B 2 - (R p - R 0 max).
When lateral slaughter, vehicles can be placed not only at the level of the excavator, on a ledge from the side of the goaf, on the surface of the earth (with a small excavation depth).
Vehicles should be placed at a certain distance from the bottom of the slope (0.5 ... 1.0 m), and also outside the zone of soil collapse if they stand on a ledge above the excavator.
The average value of the angle of rotation in the plan is determined between the directions to the center of gravity of the developed part of the soil to the center of gravity of the unloading site.
The ability to lower the handle below the level of the excavator allows it to independently enter the face without the help of other mechanisms. Deepening occurs with a gradual advance with a path slope of no more than 1:8 ... 1:10. The resulting trench makes it possible to pass the next belt with greater depth, since vehicles can already move along the bottom of the first (pioneer) trench.
If the design excavation depth significantly exceeds the maximum cutting depth of the excavator, then the development is carried out in several tiers, the number of which is determined as follows:
n i \u003d N / N p max,
where H - excavation depth; H p max - maximum depth of cut adopted by the excavator; n i is the number of development tiers, rounded up to the next higher integer.
The excavator enters each tier by laying pioneer trenches, the depth of which is determined by the soil loading conditions.
In the process of excavating the soil with a straight shovel, the excavation slopes acquire a curvilinear shape, which usually does not correspond to the specified slope shape. This requires subsequent improvements by other mechanisms (draglines, bulldozers, excavators, etc.).
General provisions. Approximately 97% of all works in the construction of earthworks are comprehensively mechanized, i.e. during the process, manual labor is completely excluded. Figure 11 shows the schemes of complex mechanization of works during backfilling of the body of an earthen dam. The soil is developed in a quarry by an excavator with loading into dump trucks (Fig. 5.11, A), transported over a distance L unloaded after lifting the body, leveled with bulldozers and compacted with rollers (Fig. 11, b, c).
Fig.11. Schemes of complex mechanization of earthworks
A- development and transportation;
b - unloading and leveling;
V- seal.
In industrial and civil construction, the following earthmoving machines are most common: earth-moving machines (excavators); earth-moving and transport (bulldozers, scrapers, graders); loosening (bulldozers-rippers, diesel hammers); transporting (dump trucks); soil-compacting (rollers, vibrating tamping plates, etc.); special machines (drilling rigs, pile drivers, etc.).
The largest volume of earthworks in construction (45%) is carried out by single-bucket excavators: on pneumatic wheels (standard bucket capacity 0.15 ... 0.65 m), on caterpillar tracks (standard bucket capacity 0.25 ... 2.5, less often up to 4 m). In addition to standard buckets, when excavating light soils, buckets with increased capacity can be installed.
The index (brand) of a domestic excavator manufactured before 1968 means the capacity of a standard bucket, for example, E-652A - an excavator with a bucket with a capacity of 0.65 m3, model 2, first modernization. The index of a modern excavator contains information about its main characteristics (Fig. 12). For example, EO-3322AT is a single-bucket excavator, universal, of the third size group, on pneumatic wheels, with a rigid equipment suspension, model 2, which has undergone the first modernization in a tropical version.
Fig.12. Scheme for marking single-bucket universal excavators:
EO- universal single-bucket excavator;
WITH- northern version;
T- tropical version;
TV- tropical wet version;
G - caterpillar undercarriage with the minimum allowable surface of the tracks;
GU- caterpillar undercarriage with an increased surface of the tracks;
P- pneumatic wheel undercarriage;
US- special chassis of automobile type;
A- truck chassis;
Tr- tractor;
Etc- trailer undercarriage;
Pl- floating running gear.
Excavators of outdated models of type E, as a rule, were produced with flexible suspension and cable control. Modern excavators of the EO type are produced with a rigid suspension and hydraulic control.
The main excavator equipment is the backhoe bucket. Other types of interchangeable equipment include a face shovel, grapple, dragline, grading and loading buckets.
The working area of the excavator, including the parking lot of vehicles, is called slaughter, movement of the excavator during excavation - sinking. The value of moving an excavator when changing an adjacent parking lot is called travel length. Faces are frontal (when using a backhoe - end) and side, penetrations - longitudinal and transverse. Depending on the number of penetrations along the height of the excavation, one-, two- and three-tier excavation is distinguished.
The working cycle of an excavator has five main operations: digging, moving the bucket, unloading the bucket into a dump or vehicle, reverse rotation for digging, lowering the bucket for subsequent digging. To reduce the cycle time, excavators usually combine the fourth and fifth operations when loading soil into a vehicle, and the second and third operations when dumping soil into a dump.
The performance of the excavator and other earth-moving and earth-moving machines
T, T- respectively, the operating time of the machine, the excavation cycle time;
q- geometric capacity of the bucket (earth prism);
TO, TO,TO- respectively, the coefficients of filling the bucket, loosening the soil, the use of time during the shift.
Productivity can be improved as a result of the following activities:
shortening the excavation cycle ( T), combining work operations, reducing the angle of rotation of the boom during unloading, loosening the soil during breaks in the supply of transport, etc.;
increase in the volume of soil developed in one cycle (q, K), in the case of using buckets of increased capacity, their more complete filling ("with a cap"), etc.;
coefficient increase TO in the process of reducing downtime (timely preventive maintenance, presentation of the scope of work, transportation of fuels and lubricants, etc.).
Selection of excavator and vehicles. The excavator can be selected according to the scope of work, the specified deadlines for the completion of work or the required characteristics of the machines. When taking into account the scope of work, you can be guided by the data below (Table 7).
Table 7
|
Scope of work Q, m |
Over 20000 |
||||
|
Capacity bucket q, m | |||||
|
shifting |
With a given deadline for the completion of work, a machine is selected that can complete the work on time, according to productivity
Q- scope of work;
T - given period.
When selecting an excavator according to the required technical characteristics, the main parameters of the machine (Fig. 13) and working conditions are taken into account.
Operating at maximum outreach (R) results in rapid wear of the machine, so optimal operating parameters are assumed ( R ), components of 90% of the maximum values shown in Figure 5.13:
When operating an excavator with loading soil into vehicles, the number of required dump trucks:
T, T, T- the duration, respectively, of loading, unloading, dump truck maneuvers;
L- transportation distance;
V- the average speed of the car (in the city V= 25 ).
Fig.13. Diagram of the main technical parameters single bucket excavator
A - maximum cutting radius;
IN- maximum digging radius;
WITH - the greatest digging depth;
D- maximum digging height;
E - maximum unloading height;
F- the greatest depth of cut;
G- minimum radius of unloading;
TO - dumping radius at height E
Loading duration
,
H- the norm of time for the development of soil with its loading into vehicles (ENiR E2-1);
n- the number of buckets loaded into the dump truck;
V- the volume of soil in the bucket.
Where Q, Q - respectively, the load capacity of the dump truck and the mass of soil in the excavator bucket.
Parameter
Soil density;
q- geometric volume of the bucket;
TO- the coefficient of filling the bucket with loosened soil is assumed to be from 1 to 1.2;
TO- soil loosening coefficient (see Table 3).
Front Shovel Excavator(fig.14, A) is mainly used in the development of excavations in dry and low-moisture soils, which is associated with the need to drive to the bottom of the excavation. Apply longitudinal frontal (Fig. 14, b - d) or side (fig.14, e) penetrations with soil loading into a vehicle, which is usually placed directly in the face. For the exit and entry of vehicles, inclined ramps are arranged with a slope of 10 ... 15 °.
Fig.14. Schemes for the development of excavations with a "straight shovel" excavator:
A - general form;
b, c, d- frontal penetrations, respectively: narrow, normal width, broadened;
d- side entry
The normal width of the frontal penetration (see Fig. 14, V)
Where R, - optimal cutting radius;
L- the length of the shift, i.e. the distance that the excavator moves after excavation from the previous parking lot.
Along with penetrations of normal width [(1.5 ... 1.9) R] due to working conditions, narrow penetrations (up to 1.5 R0) And; wide penetrations [(2... 2.5) R]. Depending on the width of the penetration, the frontal faces are divided into narrow, normal and widened. Due to the large angle of rotation of the boom, the performance of an excavator operating in a narrow face is lower than when working in normal and widened faces.
For lateral penetration (see fig. 14, e) the transport is fed for loading from the side of the excavation, which reduces the angle of rotation of the excavator boom and improves its productivity.
Backhoe equipped excavators, develop excavations with end (frontal) and side penetrations (Fig. 15), located above the bottom of the face, which allows: to use them in the development of moist and wet soils, with loading into a vehicle or into a dump.
Fig.15. Excavator driving options with backhoe working equipment:
A- end (frontal);
b- broadened frontal;
V- cross-end;
G- side;
d- face with unloading of soil in transport and in a dump;
1 - dump truck;
2 - excavator.
Transport can be fed along the bottom of the excavation or on top from one or two sides. The depth of the face is determined by the length of the excavator handle. The width of the end penetration for two-sided loading of dump trucks is (1.6 ... 1.7) R, for one-sided - (1.2 ... 1.5) R. When working in the dump, the width of the penetration is less - (0.5 ... 0.8) R. When lateral driving, vehicles for loading can be fed along the top or along the bottom of the pit, from the right or left side (Fig. 16).
Grab bucket excavators used in the development of narrow or deep recesses (trenches, wells) in soft and loose soils, including those with a high level of groundwater. The bucket can be mounted on a handle or hung on a lattice boom, the soil is collected using a hydraulic drive or a heavy bucket plunging into the soil (Fig. 17, a, b). The hydraulic drive system allows you to develop dense soils with light buckets, which makes it possible to collect more soil into the bucket in one excavation cycle. The productivity of excavators with such equipment is significantly increased. When extracting small, deep excavations, an excavator equipped with a clamshell bucket works without moving. When extracting trenches, it moves along the trench, so transport can be accessed from any free side.
Fig.16. Soil development schemes with an excavator equipped with a backhoe bucket:
A, b - with rigid and flexible suspension;
V - development of soil in the continental occurrence with the installation of vehicles above and below the excavator parking lot;
G - development of pre-loosened soil;
d, e - car access options.
Fig.17. Soil development schemes by excavators equipped with "grab" and "dragline" buckets:
a, b - when installing the grab on the handle and lattice boom;
c, g- work with a bucket "dragline";
I- the position of the bucket when collecting soil;
II- the same when lifting and unloading.
Dragline(fig.17, V, G) they are used when excavating soil below the level of the excavator parking lot, without going to the bottom of the excavation, so the presence of groundwater does not affect the operation of the machine.
Dragline is used for digging relatively large pits and trenches, as well as for filling embankments, in particular in the construction of canals, roads and railways.
When using a dragline, excavation can be carried out by frontal or side penetrations. Since the bucket is suspended on a rope, when loaded, it swings and is thrown over a distance exceeding the length of the boom; often use shuttle methods of work (Fig. 18, a, b).
With the cross-shuttle method, the dump truck is loaded by alternately scooping the bucket from both sides of the body. With a longitudinal shuttle, the soil is collected in front of the tailgate of the dump truck body. The angle of rotation of the excavator boom when loading according to the longitudinal-shuttle scheme approaches 0, and with the transverse shuttle - to 15 ... 20 °. During unloading, the movement of the bucket does not stop, due to which the duration of the excavation cycle is reduced by 20 ... 26 %.
Fig.18. Soil development methods
A- transverse shuttle;
b- longitudinal shuttle;
V- "to myself";
1 - bucket lifting;
2 - lowering the bucket when collecting soil;
3 - unloading of the bucket;
4 - dump truck.
Telescopic boom excavators(fig.18, V) work in the same way as excavators equipped with a backhoe. However, in addition to conventional excavation work, this equipment can be used to perform cleaning and grading work, which is an advantage in the development of small dispersed earthworks. To increase the speed of movement from object to object, there are pneumatic excavators. Their boom retraction mechanism is adapted for digging soil, leveling and cleaning surfaces, loading bulk materials and piece cargo.
Caterpillar and pneumatic wheel loaders (Fig. 19), like a straight shovel, work above the parking level of the machine by moving the bucket away from itself. The capacity of the loader bucket is 1.5...2 times greater than the capacity of the bucket of a straight shovel, which can significantly increase the performance of the excavator. The movement of the cutting edge of the blade along a straight horizontal path allows you to plan the site on which the machine works. Thanks to the ability to move the soil over short distances, the work of shovel loaders is especially effective in cramped conditions. The bucket is filled with stepped, excavation, separate and combined methods (see Fig. 19, I-IV respectively).
Fig.5.19. Soil development schemes with single-bucket loaders
A- on a pneumatic duct;
b- on caterpillar tracks,
V , d, e - accordingly, rotary, shuttle and combined schemes of excavation.
