Vertical layout of the construction site. Vertical layout of the construction site Execution of the vertical layout
The vertical layout of the construction site is part of preparatory period in construction. Grading is an artificial change in the terrain according to the design data.
The resulting site with design marks can already be used for further work. Before the start of all construction processes, it is necessary to obtain a permit for the production of work and only then proceed to the development of the territory.
The planning of the construction site is carried out by cutting the soil and filling it in required volumes and locations. It is a mandatory component before starting the construction of the facility.
The building area is leveled, slight slopes are arranged, which serve to remove rain and melt precipitation from the construction site.
If necessary, arrange additional earthen structures - drainage or drainage ditches, embankments, etc. They prevent the flow and accumulation of atmospheric water to the construction site from neighboring territories.
The main stages of vertical planning
The vertical planning must be carried out with the maximum preservation of the natural relief of the area. When calculating in terms of the smallest volumes earthworks.
At the same time, it will be correct to preserve the fertile soil layer where possible. If this cannot be done, then the humus layer of the soil is removed and moved outside the construction site. Subsequently, the cut layer will be used for landscaping.
Performed to prepare a building plot. It is the initial part of the building plan.
The execution of vertical planning can be conditionally divided into several stages:
- Removal and relocation of the vegetative layer of the soil;
- Development of earth masses by cutting off embankments and moving them into existing excavations;
- Backfilling of the design embankment with leveling and soil compaction;
- Final planning of areas and slopes in embankments and excavations.
Depending on the ground conditions(high groundwater level, weak soils, other) the layout also achieves the solution of other problems.
For example, by erecting an embankment (ground cushion) under the future structure, it is possible to ensure that the foundations are located above the level of subsoil waters. This makes it possible to carry out construction where it was not possible before.
The vertical plan drawings are included in the section of the master plan working drawings set, which includes:
- Summary data of working drawings;
- Landing plan of structures on the ground;
- Plan of the projected relief (slopes, contours, ground elevations of structures, etc.);
- The plan of the moved masses of soil (excavations, embankments);
- General plan of engineering communications;
- Landscaped area plan (roads, sidewalks, small architectural forms).
As part of the arrangement of the territory, the vertical planning solves certain problems:
Organizes a drain from the building area - storm, rain, melt water;
Solves the problem of planting buildings, structures, laying underground utilities with the least amount of earthwork;
Provides permissible slopes of streets, driveways, playgrounds, sidewalks for traffic in a safe mode of vehicles, pedestrians;
Organizes the projected relief;
It will not be superfluous to note that in the production of work (POS, PPR) there are requirements for the layout of the construction site.
Correct vertical leveling of the construction site is essential for the accurate installation of jib and tower cranes. As well as scaffolding and scaffolding on the facades of buildings, the correct storage of building materials and structures.
Geodetic works on vertical planning
The project on geodesy of vertical planning is developed by the specialists of the design firm. There are two main types of vertical planning projects development.
- Designing a horizontal area while maintaining the balance of earth masses.
- Design of inclined platforms.
The balance of earth masses is a condition under which the difference between the volumes of cutting and filling of soil should be as close to zero as possible.
If the volume of soil extracted during the development of excavations can be completely laid in an embankment erected on a construction site, then the balance is called zero.
This option can be called optimal, since it does not require additional costs for the development of soil, its loading and transportation.
The design is based on the existing topographic surface of the construction site. V general view the simplest and most common is the following technique.
Geodetic survey (leveling) of the construction site is carried out on a grid of squares. The length of the side of the square is taken from 10 to 100 meters.
The tops of the squares are marked on the ground with pegs. Based topographic survey the elevations of the tops of the squares calculate the design elevation of the planned (horizontal) construction site.
Then the working marks of the intersections of the squares are calculated (plus - add, minus - cut off), as well as the position of the places and lines of zero works. After that, the volumes and cartogram of earth masses are calculated.
A similar technique is used when designing ramps. The vertical layout of the construction site is carried out already taking into account the slope specified by the project.
Performing vertical planning
The preparatory activities include cleaning work construction area from trees, bushes, stumps, boulders and more.
In addition, the diversion of surface water, drainage of the territory, the breakdown of the construction area for planning activities, cutting off the vegetation layer of the soil.
Main works:
- Development of soil in places where it needs to be cut with moving to places where it needs to be poured;
- Leveling, compacting it in embankments;
- Removal or delivery of earth masses to the construction site, if necessary;
- The final is the layout of the site.
The vertical leveling is carried out using earthmoving machines. For small volumes of work, bulldozers of small and medium power are used.
When moving the soil at a distance of 80-100 meters - high-power bulldozers or small scrapers with a bucket capacity of up to 3m3.
When moving earth masses over a distance of 120 meters, it is most advisable to use scrapers with a bucket capacity of 10 m3 or more.
In some cases, instead of scrapers, it may be more expedient to use excavators in tandem with transport units.
When calculating the volumes of the developed soil, you should know that the developed (loosened) soil increases in volume. The difference fluctuates within 30% versus the volume in the dense state.
Acceptance of the completed earthworks is carried out by the geodetic service of the general contractor from the contractor. V necessary cases(stipulated by the project) the contractor submits the results of soil compaction analyzes. The vertical layout of the construction site is an important preparatory stage for the construction of the facility.
The cut off plant soil is stored at the construction site or transported to the place of recycling.
Based on this condition, as well as the distance of soil transportation, one of the following work methods is chosen:
1. Cutting off the layer with an earth-moving machine, loading into vehicles with an earth-moving machine and transportation to the place of storage (use).
2. Cutting off the layer and transporting it with an earth-moving machine.
In the first case, as a rule, a bulldozer is designated as the main earth-moving machine, an excavator and dump trucks are assigned as an auxiliary one. In the second, all operations are performed by a scraper.
The selection of a set of mechanisms begins with the selection of the leading machine for excavation. Then, based on the productivity, cycle time and the main parameters of the leading machine, auxiliary machines are selected for loosening, transportation, leveling, compaction and other possible types of work.
Considering that one and the same work can be performed by different sets of machines, and the same set can work according to different technological schemes, when pre-selecting the sets, they are guided by the provisions established by practice.
Large machines with high productivity are economically profitable to use on jobs with significant volumes, and for small volumes of work, it is cheaper to use small machines.
The development of soil with bulldozers is carried out mainly in two ways: trench and layer-by-layer .
Rice. 2. Scheme of soil development by a bulldozer:
a - trench; b- layered; 1 , 2 , 3, - cutting sequence The trench development method is used to reduce losses when moving soil at a distance of up to 50 m. Parallel strips - trenches with a depth of 0.4 to 0.6 m - are obtained by several bulldozer passes at the same place. The width of the trenches is taken to be equal to the length of the bulldozer blade, and the jumpers left between the trenches are 0.4 m wide in cohesive soils and 0.6 m in poorly cohesive soils. The lintels are developed after the passage of each trench.
Rice. 3. Trench method of soil development when filling the embankment: 1 - bulldozer driving trenches; 2 - intermediate rollers; 3 - jumper between trenches; 4 - embankment.
The distance of transportation over 50 m is arranged every 25 m with intermediate shafts, which are then moved by two or three paired bulldozers.
The method of arrangement of intermediate rollers is as follows. On the way of transporting soil, every 40 ... 50 m, areas for the location of intermediate rollers of soil are outlined. The bulldozer develops and moves the soil with separate grabs. First, the soil moves into the first roller, then into the second, third and further outside the excavation. This increases the number of idle strokes of the bulldozer, but with each working stroke, the bulldozer moves the maximum volume of soil. With the trench method of soil development, its losses are significantly reduced due to a decrease in shedding from the bulldozer blade in the process of transporting the soil to the place of its dumping.
With the layer-by-layer method, the recess is developed in layers for the thickness of the removed chips in one pass of the bulldozer sequentially over the entire width of the recess or its individual parts. This method is used for shallow cut-off depths and complex landforms.
With a layer-by-layer scheme, soil development is carried out in parallel strips, with each previous strip overlapping with the next one from 0.3 to 0.5 m.
Fig. 4. Calculation scheme for cutting off the vegetation layer. L Wed- average distance of movement of vegetative soil during embankment, h- the height of the soil dump, A- strip for clearing plant soil, V- the width of the dump of vegetable soil at the bottom, b- the width of the dump of vegetative soil at the top.
On the clearing strip A(up to 150 m long) by movements of the bulldozer from the edges to the center, a dump of plant soil is formed with a width ; area
, where b accepted in the range of 1.5 ... 1.9 R, and R- cutting radius at the level of the tracks for the excavator used for loading (selected by).
Blade height h taken from 2 to 4 m. Average distance of soil movement L Wed = A/ 4, m.
To remove the vegetation layer, a bulldozer is selected based on the T, T-100, T-130 and T-180 tractors along the trench width, respectively, 20-40 m, 40-60 m, 60-100 m. The main characteristics of the bulldozer are the bulldozer brand, length blade, blade height, blade type, control, power.
An excavator is selected to mine the cut soil and load it into a vehicle. The most preferred excavator is a straight shovel. When the volume of work is more than 10 thousand m 3, it is recommended to use machines with a bucket capacity of 0.5 m 3 or more. The main characteristics are the brand of the excavator, bucket capacity, boom length, largest digging radius, largest unloading radius, maximum unloading height, power.
Operational performance of the bulldozer P eb:
(17)
V p- the volume of the drawing prism, m 3,
where B 0 and N- accordingly the length and height of the dozer blade, m; K p- coefficient of soil loosening, by; φ 0 - angle of natural slope of loosened soil; NS- coefficient of accounting for the slope of the terrain (Appendix 2); To c- coefficient of soil conservation on the knife during transportation, To c=1-0,005L Wed; To in- the coefficient of use of the bulldozer per shift by; T- the unit of time for which the bulldozer performance is determined, 8 hours; T c- working cycle time, sec;
T c = t p + t p + t xx + t m, (19)
where t p- soil cutting time,
t p- duration of movement:
t xx- idling duration:
t m- maneuvering time.
Cutting, soil movement and transportation speeds are given in Appendix 2.
The number of machine shifts required to complete the work is determined by the formula
V gr- the volume of the excavated soil, m 3.
The number of bulldozers and the shift in their work are determined during the period of scheduling the production of work, based on the period of time allotted for the performance of this type of work (initial data).
Excavator operating performance
, m 3 / cm (25)
where q- bucket capacity (m 3); To n- bucket filling factor (Appendix 3); t cp- cycle time when loading a vehicle (min) according to (Appendix 3); K p- coefficient of soil loosening by; T- unit of time for which productivity is determined (8 hours); To them- the utilization rate of machines per shift, depending on the soil group.
Excavator standard performance:
where N vr- time rate, man-hour per 100 m 3 of soil.
In the further calculation, the lowest performance is used.
The required number of excavator machine shifts is determined by the formula (24).
Calculation of the required number of vehicles for an excavator
We begin the calculation with the choice of the type of vehicles according to Appendix 5. The following factors influence the choice of the brand and number of dump trucks: the carrying capacity of the dump truck and the excavator output. With an increase in the carrying capacity of a dump truck, the downtime of the excavator decreases and its output increases. But the more powerful the dump truck, the more expensive the cost of a set of cars. Rational ratio of bucket capacity q(m 3) to the carrying capacity of the dump truck Q, t, 1:10, i.e. for excavator with bucket capacity q= 0.65 (m 3) it is more expedient to use a dump truck Q= 7 t, etc. (Appendix 3.5). The characteristics used are payload, body capacity, turning radius, headroom, loading maneuvering time, unloading maneuvering time, laden speed, empty speed.
When choosing a car Vehicle, the following conditions must be observed:
The side height must be at least 100 mm lower than the loading height of the excavator;
It is necessary to strive for 4 to 7 buckets of soil to be immersed in one machine, because with a small amount of soil in the body of a dump truck, undesirable dynamic loads arise during movement, and with a large number of buckets, the loading time increases.
Number of buckets n to calculated by the formula
, (27)
where V forges itself- carrying capacity of a dump truck, t; To n- bucket filling ratio; - excavator bucket capacity, m 3; K p- coefficient of soil loosening.
The number of buckets is rounded up to a whole number, both up and down, taking into account the possible overload or underload of transport within 10%, while the mass of soil in the body, t:
γ cf - average density in natural occurrence, t / m 3, by.
According to the formula (27), the number of buckets required to fill the transport is determined based on the carrying capacity without taking into account the capacity of the body, therefore, it is necessary to check the capacity of the soil in the body
(32)
When transporting light soils, the geometric capacity of dump truck bodies may not provide loading in terms of carrying capacity. In such cases, it is recommended to build up the boards with temporary shields.
Working cycle time:
T c = t p + t pr.gr + t p + t m + t pr.p, (29)
where t p- parking time under loading, min,; - the duration of the excavation cycle of a single-bucket excavator (Appendix 3); t pr.gr- excavator cycle time; t pr.gr- run time of a dump truck to the place of unloading, taking into account delays on the way, min; L- distance to the dump site (km); K n- coefficient of increasing the running time due to deceleration during braking and acceleration according to (Appendix 5); t p- unloading time, min (2-4 min); t m- maneuvering time, min (5-15 min); t pr.p- running time empty, min.
, - the speed of the dump truck empty and laden, respectively.
Based on the above, we select the number of vehicles :
Vertical layout of the site
The technological process for the vertical layout of the site consists of following operations: preliminary loosening of the soil (if necessary); cutting it off; transportation to the place of laying, leveling (if necessary) and compaction.
It is recommended to take a bulldozer or a scraper as the main earth-moving machine. An excavator for this type of work in industrial and civil construction is rarely used.
It is recommended to move the soil from the excavation to the embankment by a bulldozer at a movement distance of up to 50 m - according to the usual scheme; 50-100 m - with soil accumulation in intermediate shafts; more than 100 m - the use of a bulldozer is impractical.
Building a cartogram of earthworks
An earthworks cartogram is a graphical representation of the amount of work being performed. It indicates: a breakdown of the site into squares; working, red and black marks; the amount of work on the squares; the position of the zero line of work (LPR) and the slopes of the construction site.
The average distance of movement of earth masses determines the choice of the type of earth-moving vehicles, the area of effective use of which is set according to the rational distance of soil transportation. In addition, this parameter is necessary when finding time rates and rates. When comparing several variants of planning works, the range is calculated with an accuracy of 1 m.
There are several ways to find the average distance for transporting soil. In this case, in practice, two approaches are implemented. If the amount of work is small and the site has one open zero line, then the average distance of soil movement is determined as a whole for the entire site. In some cases, a grid of squares may intersect with multiple zero lines or have one closed line. Then the site is divided into several sections, subject to the zero balance volumes of excavation and embankment at each site, several distances of soil movement are calculated and the weighted average distance is found.
In the course project, in the presence of a checkerboard balance sheet of earth masses, the average distance of the soil L cp can be determined by the formula
where v i Is the partial volume of the excavation moved from i-th square, m3; L i Is the distance over which the given volume is transported, m.
Since the plan for the distribution of earth masses according to the checkerboard balance method is not optimal, the calculated value L cp will have errors.
Also, the average distance of soil movement can be roughly determined as the distance between the centers of gravity of the excavation and the embankment by the method of statistical moments. The moments of volumes are calculated relative to any coordinate axes:
Here V in,V n- the volume of soil within the simplest figures, m 3;
X in, X n, y in, y n- coordinates of the centers of gravity of the simplest figures , m 3.
Development of a soil movement scheme
With an approximate method for determining the average distance of soil movement during site planning, the planned labor and machine costs are significantly lower than the actual ones. In addition, the movement of soil during the production of work is rather haphazard, which in turn increases the gap between the planned and actual values of costs.
For the normal organization of work, it is necessary to build a soil movement scheme.
When using a bulldozer for vertical leveling of the site, the calculation should be carried out according to the formulas (17) ... (24).
When developing a scheme for the movement of scrapers, it should also be remembered that their performance is affected by the direction of the slope of the site, as well as the fact that they cut the soil and fill the bucket only when the scraper moves in a straight line.
Clearing the territory of the construction site is a complex of measures, including the production of work on cutting down trees and shrubs, uprooting stumps and cleaning stones, preserving the fertile soil layer, demolishing buildings, utilities and communications, backfilling holes, pits and trenches, cleaning and planning the territory and others. types of work.
Clearing the territory and cutting off plant soil is carried out in accordance with the project for the production of works, which indicates: the thickness of the cut off layer of plant soil, places for cutting, collecting and dumping of plant soil; methods of protection against damage or transplantation of trees and plants used in the future; storage areas for plant soil cut from the construction site, suitable for use in landscaping and landscaping; methods and procedure for soil reclamation.
The boundaries of the areas to be cleared should be fixed with clearly visible milestones, indicators, benchmarks.
Deforestation or replanting of forest and shrubs on the territory of the construction site is carried out only with the consent of the authorities local government and State authorities technical supervision and obtaining a felling ticket strictly within the boundaries established by the project. Green spaces that are not subject to felling should be marked with signs or fenced and transferred for safekeeping. construction organization according to the act with the attachment of a diagram of their location on the ground.
Clearing the area from trees can be done with cutting trees on site and then removing the logs or cutting felled trees outside the construction site.
Removal of the remnants of roots from the vegetation layer is carried out immediately after clearing the area from stumps and logs. The removed roots and bushes are removed from the cleared area to specially designated places for subsequent removal.
Vegetable soil to be removed from the built-up areas must be cut off, moved to specially designated places on the construction site or beyond and placed in dumps for further use in the reclamation of disturbed lands or for other needs in accordance with the project.
Before the start of work on cutting the soil of the vegetation layer, the following work must be performed:
- the axes were taken out and the boundaries of the site (route) of the production of work were marked;
- the places of dumping of dumps of vegetative soil are indicated;
- a working breakdown of the site was made with the fixing of road signs;
- familiarized with the technology and organization of work and trained in safe working methods, workers and engineering and technical workers.
When working with plant soil, do not mix it with the underlying non-plant soil, and also pollute it with waste, construction waste.
Reclamation of disturbed lands is a complex of engineering measures for the technical preparation of lands for subsequent targeted use and biological development of lands to restore their fertility.
All lands disturbed by construction are subject to reclamation, in which changes have occurred, expressed in disturbance of the soil cover, in the formation of new forms of relief, changes in the hydrogeological regime of the territory (desiccation, flooding), as well as adjacent lands, on which, as a result of construction, there was a decrease in productivity.
Reclamation is carried out in two stages - technical and biological.
The technical stage provides for the implementation of measures for the preparation of lands vacated after the development of the deposit, for subsequent targeted use in the national economy. These include: rough and fine leveling of the surface of disturbed lands; flattening and (or) terracing of slopes of dumps and sides of quarry excavations; preparation of sites (deforestation, shrubbery, removal of stones, etc.); selective removal, transportation, storage (if necessary) and application of potentially fertile rocks and a fertile soil layer to reclaimed land; elimination of the consequences of sedimentation of dumps of open-pit mining and anti-erosion measures; backfilling with rock or water filling the residual quarries; a set of reclamation measures aimed at improving the chemical and physical properties of dump soils that make up the surface layer of reclaimed lands (if necessary); construction of roads and hydraulic structures, etc.
The biological stage of reclamation includes measures to restore the fertility of reclaimed lands. These include: planting trees and shrubs, sowing perennial grasses, carrying out agrotechnical measures, phytomelioration and other work aimed at restoring flora and fauna.
4. Preparation of the construction site. Cutting of vegetable soil, planning of the territory.
Having completed the construction of a drainage ditch and a water protection shaft from the soil taken out during the development of the ditch, they begin to cut off the plant soil. Cutting of plant soil is performed with a bulldozer. In this case, the bulldozer performs two operations, development and movement of the soil. Vegetable soil is stored in a pile, which can be placed according to the above-described scheme. In this case, we will receive an additional water protection structure. All soils are classified according to the group of difficulty of their development by one or another earth-moving machine. The same type of soil for different machines may have different groups of development difficulties. Moreover, depending on the moisture content and density of the soil of the same variety, the presence of foreign inclusions in it, the difficulty group may vary for the same machine. For example, the vegetative soil belongs to the soils of the first (I) group in terms of the difficulty of bulldozing if there are no roots of trees and shrubs in it. If the plant soil contains the roots of shrubs and trees, then the difficulty of its development increases, and such soil is already referred to the second (II) group in terms of the difficulty of bulldozing. The difficulty group of the soil for development determines the resistance of this soil to cutting. Therefore, cutting of soils of different groups of difficulties is carried out according to different schemes. For example, if the vegetation soil is thin and belongs to the soils of the first group in terms of the difficulty of bulldozing, and the bulldozer has sufficient power, then the soil is cut to the full depth along the entire length of the section within which the bulldozer blade is filled. This cutting pattern is called tape cutting. The name of the schemes comes from the shape of the cut soil shavings. The band cutting scheme is also used in the development of the most difficult soils belonging to the IV group. However, in this case, the bulldozer blade is not buried in the soil to its full height, and the length of the section within which the blade is filled with soil increases significantly. This leads to a sharp decrease in the performance of the bulldozer. If the power of the bulldozer is not enough to overcome the resistance of the soil, cutting it to full depth along the entire length of the section, the blade is raised as the bulldozer moves forward. In this case, the shavings of the cut soil have the shape of a wedge, and the cutting pattern is called wedge. The wedge cutting pattern is used in the development of soils of the II group by the difficulty of development. Analyzing the material presented, we must understand that the soil cutting scheme is determined by its group of difficulties in the development and power of the bulldozer. Moreover, in all cases, the bulldozer must be selected so that its power corresponds to the group of soil difficulty. In this case, we exclude the influence of the power factor of the bulldozer on the soil cutting pattern. The difficulty of mining soils can be reduced by performing additional technological operations. For example, dry soils and soils with foreign inclusions can be loosened with a ripper immediately before excavating the soil. Waterlogged soils, in which there is adhesion of soil to the knife and cutting edge of earth-moving machines, as well as inconvenience in moving machines, can be drained by building surface and deep drainage systems. It should be borne in mind that any of our decisions must be justified. For example, if the technical and economic indicators increase when performing operations aimed at reducing the difficulty of soil development, then these additional works are justified from the standpoint of economics and labor intensity. Otherwise, it is not advisable to perform additional operations.
Figure 5 shows schemes for cutting plant soil with a bulldozer.
Figure 5 - Schemes for cutting vegetative soil of groups I and II
difficulties with a bulldozer: a) tape; b) - wedge.
The surface of the site in the construction zone is planned with a bulldozer with inclinations to ensure water flow from the pipe.