"Backhoe" used when scooping onto yourself. The soil is being developed below the parking lot level. This method used for excavating trenches of pits of insignificant depth.
Peculiarities:
1. – frontal or side face is used;
2. – tiered soil development is not used.
Features include the type of soil:
1. – in non-cohesive soils (sand, sandy loam), the depth of the face is 1-1.7 m;
2. – cohesive soil (clay, loam) – from 1.5-2.5 m.
Features of development of soil shortage (soil shortage from 5 to 30 cm):
This shortage is carried out by bulldozers or excavators, and cleaning buckets. The stripping accuracy is ±2cm.
1. – fill the bucket as much as possible each time you dig up soil;
2. Less time is spent on auxiliary operations (moving, cleaning the bucket).
Maximum cutting height;
The largest cutting radius is at the parking level;
Largest cutting radius.
Technical characteristics are determined on the basis of the passport data of this excavator.
All earthworks performed by single-bucket excavators are divided into two groups: non-transport and transport.
Non-transport schemes are those schemes in which an excavator develops soil and places it in a dump (embankment), cavalier or in an earthen structure. In a simple transport-free development scheme, the soil is placed in a dump or cavalier without subsequent transshipment (re-excavation), in a complex one - in a temporary (primary) dump and is subject to partial or complete re-excavation.
Transport schemes are those in which soil is loaded by an excavator into dump trucks (Fig. 1) and transported to a given location. In this case, it is possible various schemes transport movements: dead-end (dump trucks drive up to the excavator and return along the same path) and through (dump trucks drive up to the excavator without maneuvering and, after loading, leave along the road, which is a continuation of the entrance route).
Fig.1. Transport schemes for the operation of an excavator equipped with a straight shovel
a - frontal wide penetration with loading of soil into vehicles moving along the bottom of the face; b - lateral excavation with loading of soil into vehicles
The scheme of work depends on the construction features. For example, in water management, oil and gas pipelines and transport construction Non-transport schemes predominate, while transport schemes predominate in industrial and residential areas.
Soil development using single-bucket excavators is carried out by tunneling. The number of penetrations, faces and their parameters are provided for in projects and production flow sheets earthworks for each specific object in accordance with the parameters of earthen structures (according to working drawings) and with the optimal working dimensions of excavator equipment.
Soil development is carried out by frontal or lateral penetrations. During frontal excavation, an excavator, the axis of which coincides with the axis of the earthen structure or is located in its cross-sectional area, develops three slopes of the excavation - two side and end.
There are two types of side penetrations: closed (Fig. 2, a, b), when the axis of movement of the excavator is located on the side of the excavation section (the excavator develops, three slopes - two side and end) and open (Fig. 2, c), when the excavator moves along the strip and develops two slopes (side and end).
Fig.2. Scheme of excavation development using an excavator equipped with a backhoe
a - lateral closed penetration and equal slope slopes; b - the same, with different steepness of slopes; c - side open penetration
The face is the working area of the excavator, which includes the platform on which the excavator is located, part of the soil mass removed from one parking lot, and a site for parking vehicles under loading.
The parameters of the penetrations and faces must ensure the ability to operate the bucket with the least amount of time required to complete the excavation work cycle. To do this, take the width of the penetrations (faces) in such a way that the excavator can operate at average rotation angles no more than 70; depth (height) of the faces - not less than the length of the soil shavings required to fill the bucket “with a cap” in one scooping (digging) step; the length of the passages - taking into account the possible minimum number of excavator transitions in the face. The slopes of the penetrations are designed to prevent the influx and accumulation of ground and surface water in the faces.
The machines have working equipment of different types and bucket sizes, mechanical or hydraulic drive. On mechanical excavators, the bucket is rigidly connected to the handle and its movement is carried out due to the pressure force of the handle and due to the traction force - by ropes. In hydraulic excavators, the movement of the bucket occurs due to the forces of the hydraulic cylinder rods of the boom, arm or bucket.
The excavator's workplace is the area of its work within geometric parameters working equipment, as well as the dimensions of the vehicle parking area for loading soil and placing it in a dump during excavation.
During construction engineering structures Single-bucket excavators with various replaceable equipment with a bucket with a capacity of 0.25...3.2 m 3 are widely used. The choice of the type of single-bucket excavator depends on the nature and conditions of the work performed, the size and type of earthen structure. An excavator equipped with a straight shovel (Fig. 4.5, a) is intended for the development of soils of groups I-VI and crushed rocks above the excavator parking level. In the presence of groundwater their level should be reduced so that workplace the excavator was dry. A straight shovel is used, as a rule, for developing pits, trenches, reserves with loading soil into vehicles and, less often, for removal.
Rice. 4.5.
Bucket excavators:
a - straight shovel excavator:
1 - running device;
2 - rotating platform;
3 - handle;
4 - boom;
5 - ladle;
6 - hydraulic cylinders;
b - diagram of the working place of an excavator with a straight shovel;
c - backhoe excavator (main technological parameters);
g - dragline excavator:
1 - arrow;
2 - ladle;
3 - lifting rope;
4 - traction rope;
d - technological parameters of the dragline workplace;
e - technological parameters of an excavator equipped with a grab
The main technological parameters of the excavator workplace are the parameters that ensure its efficient operation (Fig. 4.5, b).
The radius of the overall zone (R0) ensures the development of the front and side parts of the slope of the developed area and is equal to the radius of the overall undercarriage. The smallest digging radius at parking level (R1) determines smallest size sites for installing an excavator:
R1 = Ro + Go, where Go depends on the size of the bucket, the tilt of the boom for mechanical excavators, and the position of the bucket relative to the handle for hydraulic ones (Fig. 4.5, b).
To protect against the impact of the bucket on the undercarriage, a margin of 10...15 cm is introduced.
Largest digging radius at parking level
R2 = R1 +a, where a is the horizontal path of the bucket.
The value a for mechanical excavators is determined by the possible length of the horizontal movement path of the bucket from position b to position c, when Bottom part the front wall of the bucket rests on the ground and crushes it with further movement.
For hydraulic excavators, a is determined at the standing level by the amount of possible movement along the horizontal plane of the front wall of the bucket. For hydraulic excavators with a rotary bucket, the horizontal path of the bucket is very long and to determine R2 is taken equal to a/2. In practice, for excavators with a bucket capacity of 0.4...3.2 m3, the value R2 = 4...9 m.
The largest digging radius R3 is equal to greatest distance horizontally from the platform axis to the cutting part of the bucket. For mechanical excavators, R3 is determined by the working position of the bucket with the arm fully extended forward and the boom angle of 45°. For hydraulic excavators, R2 is determined at the height of the boom heel when the bucket is under optimal angle digging, the handle is turned extremely forward, and the boom is installed with an inclination angle of 20...25°.
After excavating the soil at the workplace, the excavator is moved to a distance a. The greatest length of movement is a. For mechanical excavators, it depends mainly on the angle of the boom. Hydraulic excavators with a rotary bucket are able to move a greater distance, but this requires taking into account the height of the working face and reduces the productivity of the machine. It has been experimentally established that the greatest productivity is achieved with a movement equal to 0.75 a.
The excavation height (H3) is determined by the parameters of the excavator, its method of operation and the physical and mechanical properties of the soil. An increase in H3 provides higher economic indicators, but the actual height is determined mainly by the condition safe work(without “visor”). For mechanical and hydraulic excavators that develop soil by removing “chips” along the excavation slope, H3 = (0.6...0.65) Nn, where Hn is the highest (kinematic) lifting height of the bucket, or H3 = 1.2 Hn, where Hn is the height of the pressure shaft (up to the level of the horizontal position of the handle of a mechanical excavator).
Hydraulic excavators, which develop the soil by deepening the bucket anywhere on the slope by moving the boom and handle and then turning it to collect the soil, spend less time and energy digging the soil and are able to make excavations with a depth of (0.6...0.7) H3. Soil development begins from the top of the excavation slope.
Working equipment backhoe is used on mechanical and hydraulic excavators, intended for the development of soils of groups I-VI below the level of the excavator when digging trenches, small pits with loading the soil into vehicles and working freely. The excavation is carried out regardless of the groundwater level. When the flow of water interferes with the operation of the excavator or worsens the condition of the soil of the earthen structure, the groundwater level is reduced. Let's consider the main technological parameters of a backhoe excavator (Fig. 4.5, c).
The radius of the overall installation R0 is determined in the same way as for a straight shovel.
The smallest digging radius at the parking level (R1) is measured by the distance from the axis of the excavator to the point where the teeth emerge from the ground with the handle fully turned towards the boom. The value of R1 is taken from the conditions for safe operation of the excavator and must be no less than R0 + 1 m.
The largest digging radius at the parking level (R2) is equal to the distance from the excavator axis to the bucket teeth at the largest angle of rotation of the handle relative to the boom.
The largest digging radius at a given depth (R3) depends on the value of R2 and the digging depth.
TYPICAL TECHNOLOGICAL CARD (TTK)
DEVELOPMENT OF TRENCHES WITH AN E0-3322B EXCAVATOR, EQUIPPED WITH A BACKSHOVEL AND A PROFILE BUCKET, WITH SOIL UNLOADING INTO A DUMP
1 area of use
Typical routing designed for the development of trenches with an E0-3322B excavator equipped with a backhoe and a profile bucket, with soil unloading into a dump
Development of soils by earthmoving machines
Technological process excavation device includes excavation of soil with loading into vehicles or on the edge of an excavation, transporting soil, leveling the bottom and slopes.
The choice of soil development method and complex mechanization scheme depends on the volume and timing execution of work, type of soil, geometric parameters of the earthen structure and work conditions.
In complex mechanized soil development, in addition to the leading earthmoving machine, the kit also includes auxiliary machines for transporting soil, leveling, etc.
A single-bucket excavator is used as a leading machine when developing permanent excavations of considerable depth, pits and large trenches. To transport soil, dump trucks are most often used, as well as railway, conveyor and hydraulic transport. The number of vehicles and the scheme for their supply to the excavator are assigned based on the condition of ensuring uninterrupted operation of the excavator.
Bulldozers are usually used to clean the bottom of the excavation, level the soil and backfill the cavities.
The technological capabilities of an excavator depend on the type of working equipment, its drive system and the main parameter - the capacity of the bucket. Recommendations for choosing a bucket capacity and other excavator parameters depending on the excavation volume are given in the regulatory and reference literature on excavation work.
For excavations of significant volumes, excavators with a large bucket capacity are used. When developing waterlogged soils, it is preferable to use excavators with backhoe and dragline working equipment. It is advisable to excavate soil in deep trenches with fastening vertical walls, as well as in sinkholes, using a grab bucket.
Excavators with hydraulic system drives of working equipment make it possible to provide high accuracy geometric parameters of the excavation and great possibilities for automating the process of machine operation.
The space in which the excavator is located and the soil is excavated is called the excavator face. The profile of excavator faces and their geometric parameters for the main types of excavator working equipment are presented in Fig. 1.
Fig.1. Face profiles of excavators with various working equipment:
a - straight shovel with rope 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 work, the face dimensions are determined based on the conditions for ensuring maximum excavator productivity by reducing the work cycle time. To do this, the height (depth) of the face must ensure that the bucket with the “cap” is filled in one soil cutting operation, the angle of rotation for unloading the bucket must be minimal, etc.
The excavation formed as a result of sequential excavation of the soil during periodic movement of the excavator in the face is called excavator excavation.
Depending on the location of the excavator relative to the face and its movement during the excavation process, the excavation can be frontal (end) or lateral.
Trenches are developed, as a rule, in one frontal penetration. The development of pits is carried out by one or more parallel penetrations. If the excavation depth is significant, it is developed in tiers, gradually deepening until the design contour of the pit is formed (Fig. 2).
Fig.2. Schemes of excavator penetrations with working equipment "straight shovel":
a - frontal (end) penetration; b - the same, with a two-way arrangement of transport; c - widened frontal penetration with zigzag movement of the excavator; g - transverse end penetration; d- side penetration; e - development of a foundation pit in tiers:
I, II, III, IV - development tiers; 1 - excavator; 2 - dump truck; 3 - direction of traffic
Depending on the geometric parameters of the excavation and the characteristics of the working equipment of the excavator, the type, dimensions and number of penetrations are assigned.
It is advisable to use single-bucket excavators with “straight shovel” working equipment for the development of excavations of significant sizes in the absence of groundwater or its influx is insignificant.
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 at 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 at the same level as the excavator or above the bottom of the face.
Depending on the width of the excavation, the frontal penetration of an excavator can be straight, zigzag or transverse. Lateral penetration is used when developing 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 straight
;
for zigzag
;
for cross-end
;
for side
Where:
Optimal cutting radius of an excavator;
Excavator working travel length;
Cutting radius at parking level;
Number of lateral movements of the excavator;
- slope coefficient;
- face height.
To enter the pit, a trench is constructed 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.
Excavators with backhoe and dragline working equipment develop excavations (pits, trenches, etc.) of any width and depth not exceeding the maximum cutting depth. Tiered excavation with this type of equipment is, as a rule, not practiced. The excavator is placed above the face, which facilitates the development of wet and water-logged soils.
Excavation of the soil can be carried out in the direction coinciding with the movement of the excavator - end excavation and perpendicular to the direction of movement - lateral. In the latter case, the development depth is less than with the end one. Schemes of penetrations and their dimensions are presented in Fig. 3.
Fig.3. Drilling diagrams for an excavator with dragline and backhoe working equipment:
a - frontal penetration; b - widened frontal; c - transverse end; g - side penetration; d- development of a pit with two frontal penetrations; I and II - sequence of penetrations; 1 - excavator; 2 - dump truck
The soil is developed by loading into vehicles or into a dump. A dragline works more efficiently by moving soil into a dump or embankment.
The dragline excavator is designed for the development of soft, and with preliminary loosening, rocky soils below the parking level and from under water, unloading them into a dump, and sometimes loading them onto vehicles. Development is carried out either by a side face, when the excavator moves along the edge of the excavation parallel to its axis, or by a frontal face, when the excavator moves along the axis of the excavation and develops the soil on its own.
Wide excavations are developed using the side face. The soil is placed in the dump either at an average rotation angle for unloading of 130...140°, corresponding to the largest volume of the dump, or at an angle p = 170°, corresponding maximum use dragline operating parameters. Sometimes soil is loaded onto vehicles.
Using a frontal face, narrow excavations are developed with soil placed in a dump on one or both sides, or loaded onto transport. In this case, the average rotation angle is equal to 45-48°, and the operating parameters are used less than in transverse development.
Taking the position of the slope and indicating the depth of the excavation, the maximum width of the face along the bottom can be determined by selection. When working for transport, earth transporters can move at the excavator parking level, along the bottom of the face, or along a territory planned between these levels. Loading onto vehicles at the excavator parking level is carried out at a boom rotation angle of 70 - 180°. Loading at the level of the bottom of the face is carried out using a transverse or longitudinal shuttle pattern. In the first case, soil is collected alternately from each side of the earth truck and the bucket is unloaded while it is above the vehicle body without stopping the boom rotation. In the second case, the soil is collected before back wall earth truck and, lifting the bucket, unload it over the body. With this scheme, there is almost no turning movement of the excavator, and with the cross-shuttle scheme they do not exceed 15°. All this, as well as the low lift of the bucket for loading, significantly reduces the work cycle of the excavator.
Dragline excavator widely used in the development of excavations with soil movement without the use of transport. The work is carried out according to the following schemes: one penetration with one-sided placement of the dump; two penetrations with double-sided placement of the dump; two penetrations with one-sided placement of the dump; three penetrations with one-sided placement of the dump; four penetrations with double-sided placement of the dump.
The first and second schemes are used when developing narrow excavations with a width of no more than the digging radius. The third scheme is used when developing recesses with a width of (1.7-1.8), the fourth - in cramped conditions, and the fifth - when the recess width is up to (3.5-4.0).
The operation of dragline excavators without the use of transport with two or three transfers of soil or with the processing of the dump by scrapers and bulldozers, as a rule, work more efficiently excavator with a straight shovel for transport. There is no need to build roads and maintain transport.
The main operating parameters of a dragline excavator include: normal digging radius, digging radius with bucket throw, unloading radius; maximum excavation depth without throwing the bucket and with throwing the bucket, highest unloading height Reducing the boom angle from 45 to 20° increases the digging radius by 1.3 times. Taking into account the casting, the digging radius at the parking lot level is determined. Unloading radius in general case equal to the normal digging radius R. It can be increased by throwing the bucket into the dump when working.
The article reveals the main issues of operating single-bucket equipment: features of work, arrangement of the working area, selection of a model appropriate to the site being developed. The varieties of single-bucket excavators used for soils from categories I to IV are considered.
Principles and main aspects of carrying out work when developing soil with single-bucket excavators.
Excavators are the predominant technique in carrying out irrigation and general construction operations. occupies 45% of the total mass of soil excavation work. This type of machine is used for most types of activities: finishing sides, leveling the bottom of excavations, compacting the earthen layer, removing loose and frozen layers. Knowing the fundamental aspects of the development process and taking into account the type of surface being developed will help you choose the right type of equipment to use.
Device, technical equipment and work process.
A single-bucket excavator is a type of equipment designed to perform a variety of excavation and general construction operations. The production cycle consists of six stages:
- Cutting the soil layer and filling the bucket part.
- Lifting the filled bucket for unimpeded transport to the dumping site.
- Raising the boom to the unloading area. Sometimes the rotation of the boom is combined with the lifting of the bucket.
- Emptying cut rocks into dump trucks or dumps.
- Return to the cutting site.
- Feeding the bucket part for cutting material.
The movement of single-bucket equipment is carried out through the use of several types of running equipment:
- Crawler. This type provides increased cross-country ability and is used for work in difficult conditions relief.
- Pneumatic.
- Walking. Due to its small mass, it reduces the pressure exerted on the surface and increases stability.
- Rail-walking. Increases maneuverability and reduces pressure on the supporting surface.
Cutting and collecting rocks takes 15-30% of the total working time production cycle, therefore, soil development with multi-bucket excavators will be significantly higher in productivity. This occurs due to the continuity of soil sampling with 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 single-bucket machine base provides the use of four main types of equipment.
In addition to the possibility of using a dragline, grab, front and back shovels, this construction equipment can be equipped with the following components:
- Bucket rotator. A mechanism that allows you to quickly transition from front shovel operation to backhoe mode. Most often found on European models: for example, on Czechoslovakian UDS-114 models.
- Slope planner. A separate type of “backhoe” type bucket used for constructing slopes. It provides bucket movement cutting edge at a certain angle. To use the scheduler, you must install automated control.
- Ripper. It is used to destroy structures, break up asphalt or concrete pavement, and perform operations with soils from group III with a dragline excavator.
- Strug. The boom along which the cart with the bucket “runs”. Used in planning work.
Types of Bucket Excavators
According to their purpose, single-bucket models are divided into three large categories:
- Construction. Universal equipment with full rotation and bucket capacity of 0.15-2 m3. Versatility is ensured by the ability to install replaceable components for various manipulations. The development of soil 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 manipulation on difficult terrain, often used in mining.
- Overburden. Machines with a bucket whose capacity exceeds 6 m3. Operated for “overburden” – cutting upper layers breeds As a rule, they are equipped with extended equipment that increases the working radius. Stripping machines do not have the ability to install replacement equipment. Overburden construction equipment includes walking draglines with buckets with a capacity of 4 to 80 m3, used for digging trenches, filling dams, and constructing pits.
If possible, use With various types additional devices single-bucket cars are divided into three types :
- Universal. They have at least 4 types of replaceable equipment.
- Semi-universal. Machines with a bucket part capacity of no more than 4 - 6 m3. It is possible to install two or three types of additional modifications on semi-universal models.
- Specialized. Bucket capacity is more than 4 m3. They are produced with one equipment modification, without the possibility of change.
General schemes of work
Based on the type of organization of waste material removal routes, all excavation and excavation work is divided into two large groups:
- Transport-free. When carrying out this scheme, the soil layer is cut off and placed in an earthen structure; 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. In complex cases, 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 given location. With a transport scheme, two routes 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 pipeline structures, non-transportation schemes have an advantage, and in the construction of industrial and residential complexes with the possibility of arranging normal unloading routes, transport schemes have an advantage.
Development is carried out by creating special trenches - penetrations. Sampling is carried out with the construction of frontal or lateral trench penetrations. When carrying out frontal excavation, sampling is carried out on three parts of the existing site - two sidewalls and an end slope.
There are two types of side penetrations:
- Closed. Here the excavator axis is located to the right or left of the excavation section. In this case, three slopes are developed - the side sections and the end slope.
- Open. There is a gradual shift in the direction of the strip with rock sampling from the sides and the end slope.
Work area and its arrangement
The face means the working area of single-bucket equipment, which includes a central platform with the placement of an excavator and accompanying vehicles.
The face is equipped taking into account the main parameters:
- The dimensions of the structure being built and the shape of the required pit.
- Technical indicators of the excavator used. For example, when using machines on crawler, it is permissible to develop soil in difficult areas of terrain where increased cross-country ability is required.
- Technical characteristics of the road transport used. For example, if work is carried out in a marshy area, the face should be equipped as close as possible to the hard surface to increase the cross-country ability of vehicles.
Design of faces with subsequent sampling of material consists of correct definition width and depth of the face, selection of optimal installation positions of machines located on the site, sequential selection of layers and equipment of paths for moving equipment and associated transport.
If the face height is low, it is worth using a single-bucket model, supplemented by a bulldozer that rakes up soil material. The bulldozer moves it towards the "excavator" work 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 swing angle of the boom to a minimum - turning the excavator boom takes 70% of the time of the total production cycle.
Increasing efficiency indicators during excavation
To increase productivity when carrying out excavation work, you must be guided by certain provisions:
- Calculate the digging radius, taking into account the maximum values of the equipment being used. It should not be higher than 0.7-0.9 of the largest radius of the model used.
- Combine operations to reduce production cycle time. For example, combine the rotation of the platform with the lifting of the bucket part, which is moved to the place for unloading.
- Reduce the rotation angle of the platform by bringing the transport installation location closer to the trench axis. This will help reduce the loss of working time spent turning the platform.
- Equip unloading paths, ensuring rapid movement for removal of lifted material.
- Reduce the time spent moving the excavator by planning and equipping the movement paths.
- If possible, avoid moving machines under their own power, preventing premature wear of the running gear.
- Select a bucket taking into account the rock being 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.
- Monitor the ratio of the carrying capacity, the distance for removal and the volume of the bucket container.
Development of soil models with a straight shovel
A straight shovel is a type of bucket container with a completely open top part. It is rigidly attached to the handle, which is connected to the boom using a hinge. The shovel is moved forward due to the action of the pressure mechanism, and emptying is done by completely opening the bottom.
The model with a straight shovel cuts and lifts in the direction of its own motion in front of the bucket part, and then smoothly moves forward by the amount of the specified handle stroke. The development of the site is carried out until the required profile is formed by creating successive trenches.
Excavation of soil with an excavator straight shovel is carried out by carrying out trenches of two categories:
- Lateral branches with dumping of cut and raised rock into a vehicle or dump located in the direction of movement of the equipment. The height of the machines in the working area determines the type of lateral penetration: single-tier with the cars located on the same level as the excavator, and two-tier with the cars placed at different heights.
- Frontal penetrations, during the creation of which the transport for unloading is installed behind the operating equipment.
The side face is advantageous by reducing the turning angle, convenient supply of vehicles for pouring the selected material, which increases productivity. But, when operating a side face, the volume of rock lifted from one area decreases, leading to an increase in the number of machine movements.
With the frontal type of face, there is a need to drive dump trucks in reverse and install vehicles behind the operating equipment, which leads to an increase in the turning angle. This causes longer production cycles, increased time costs and reduced efficiency. At the same time, the frontal face device increases the volume of lifted material, reducing the number of movements.
The installation of side penetrations is carried out during development in quarries and the formation of excavations with subsequent loading of waste material onto vehicles.
The scope of construction of frontal faces is somewhat wider:
- The first penetrations in the development of excavations and quarries.
- Work in confined spaces that impede the arrangement of loading routes.
- Lifting rock from rock excavations.
- Carrying out manipulations in autumn-winter periods on frozen soils.
All work is carried out only using a transport scheme. This is due to the fact that small linear dimensions models with a “straight shovel” bucket part do not allow the use of transport-free rock dumping.
Excavation of models with a backhoe
A backhoe is a bucket container with a “bottom” open part and a cutting front edge. 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 moment of lifting with simultaneous turning over.
This variety is used in the development of a site located below the level of the base site. IN trenches with an excavator backhoe It is advisable to use end or side type faces, which allow digging out a bed for underground communications equipment and digging small pits. Rigid fastening of the bucket part allows trenches with vertical walls to be torn off, reducing the risk of side parts collapsing. The time spent on the work process for such models is 10-15% higher than for excavators with a straight shovel.
A foundation on bored piles, made using the described technology (TISE), can, after minor modifications, be used as a seismic isolating system for individual construction in relevant regions with increased seismicity.
When operating an end face, a machine with a backhoe moves along the axis of the trench, alternately removing soil from both sides. To increase productivity, the penetration can be expanded with side faces formed when moving away from the main trench. The limit on the width of the face is carried out only on the basis of the operational requirements of the construction equipment used and safety standards for excavating this type of rock.
Carrying out work with a dragline excavator or grab
The dragline bucket container is mounted on an extended boom. Filling with rock occurs when the bucket part is pulled back to the boom. After filling, the container is finally lifted and transferred to the unloading location. Emptying is done by loosening the draft ropes.
Soil development using a dragline It is carried out when constructing large pits or excavations with a depth of up to 16-20 m, constructing an embankment and similar work. The advantages of dragline machines are the impressive depth of lowering the boom, a working radius of up to 10 m and the ability to operate in areas with a constant influx of groundwater with the effective development of flooded areas.
Dragline work is carried out using end or side trenches. The organization of work and arrangement of penetrations is similar to excavation manipulations of equipment with a backhoe. 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.
A grab is a specialized type of bucket container with two wide blades and a rack (or rope) drive system responsible for the forced closure of the blades. Used for excavating narrow and deep areas below the groundwater level. The grab is hung on an excavator boom to excavate spaces with vertical sides. A system of forced opening of the blades holding the raised contents is responsible for emptying the bucket.
The forced lowering of the stand and the immersion of the bucket part into the rock due to its high dead weight makes it possible to use a grab bucket to develop layers of almost any density, including areas completely hidden under water. The capacity of the bucket part of the grab is 0.35-2.5 m3.
Selection of equipment taking into account the main development features and rock types
Single-bucket equipment can be used in all types of rock, including rocky soils and areas with high water flow and a constant supply of groundwater.
Soil development using multi-bucket excavators can be carried out in soils from categories I to IV inclusive. In fact, safe operation can only be carried out in areas of categories I-III that do not have large fractions exceeding 0.2 of the width of the bucket part. Manipulations in areas of category IV 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 the material being cut, the presence or possible influx of groundwater and the need to use replaceable devices. If several models are suitable for performing one type of manipulation, it is preferable to excavation of soil in trenches and other spaces excavator with a straight shovel, dragline and models with a bucket part like " backhoe».
Determining the required volume of a bucket container is carried out according to the principle of maximum filling with minimal time expenditure. The maximum load directly depends on the type of material being processed, the complexity of the cutting and the depth of the work. The maximum capacity is calculated taking into account the depth of the excavation, the type of equipment and the group of rocks.
- Do not install the machine in a work area with a pronounced slope. For installation, choose only level areas - 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 promptly remove the resulting peaks.
- In weak and moving ground areas, the path of movement of equipment is strengthened by shields laid on the ground.
- Development of Group IV sections with an excavator is carried out using additional equipment - the installation of specialized devices will prevent premature wear of the mechanisms.
- If the work area becomes very wet, production should be stopped until the surface dries.
Before starting the production process, it is necessary to carefully examine the areas for the appearance of cornices and overhangs.