How to calculate the force of foundation backfill
calculation rules
(1) the volume of trench and foundation pit backfill is calculated by subtracting the volume of excavation from the volume of buried objects (including foundation cushion, foundation, etc.) under the designed outdoor floor. The quantity of trench and foundation pit backfill = volume of excavation - volume of foundation and cushion buried under outdoor floor
(2) the backfill in the center of building is calculated by multiplying the area between main walls by the thickness of backfill. House core backfill refers to the backfill between the outdoor terrace and the indoor ground cushion, also known as indoor backfill
the quantity of backfill in the center of the house = the net area between the main walls * the thickness of backfill = (the building area of the bottom floor - the area occupied by the main wall) * the thickness of backfill = (s1-l middle * outer wall thickness - L inner * inner wall thickness) * the thickness of backfill in the formula: the distance between the designed outdoor floor and the indoor floor cushion.
Section method:
when the terrain is complex, unlating and changing greatly, or the land is narrow and long, the excavation and filling depth is large and irregular, the section method should be selected for earthwork calculation
the accuracy of earthwork volume is related to the length of spacing L. the smaller L is, the higher the accuracy is. But this method has a large amount of calculation, especially in the case of large range and high accuracy; If the section spacing is increased in order to rece the amount of calculation, the accuracy of calculation results will be reced; Therefore, there is a contradiction between calculation accuracy and calculation speed in section method
grid method:
grid method is suitable for large area earthwork estimation and some sites with small topographic relief and gentle slope change. This method is to divide the site into several square grids, and then calculate the volume of each prism, so as to sum up the volume of all the prisms to get the total earthwork
in the traditional grid calculation, the calculation accuracy of earthwork is not high. Now we introce a new method of height interpolation, namely Yang Chizhong filtering estimation method
extended data:
the common earth and rock works include site leveling, regional balance, foundation pit (trench) and pipe trench excavation, subgrade excavation, civil air defense engineering excavation, floor filling, subgrade filling and foundation pit backfilling. It is necessary to reasonably arrange the construction plan, and try not to arrange it in rainy season. At the same time, in order to rece the construction cost of earthwork engineering, implement the principle of not occupying or less farmland and arable land, which is concive to land conversion, it is necessary to make reasonable allocation scheme of earthwork and make overall arrangement
the use of earthwork survey datum is very wide, which can be used not only to assist in establishing other datum features, but also to assist in defining the location of modeling features or component installation and positioning. Pro / Engineer Wildfire provides four types of datum points
datum feature is the reference feature of part modeling, and its main purpose is to assist the creation of 3D features, which can be used as the reference surface of feature section drawing, reference surface and control point of model positioning, reference surface for assembly, etc. In addition, datum features (such as coordinate system) can also be used to calculate the quality attributes of parts and provide manufacturing operation path
The buried depth of the foundation is the vertical distance from the outdoor design floor to the bottom of the foundation
The foundation with a depth of5m or more is called deep foundation; The foundation buried between 0.5m and 5m is called shallow foundation. The buried depth of foundation shall not be less than 0.5m. The buried depth of foundation is determined by other conditions and minimum buried depth. The foundation height is mainly determined by the anti punching requirements, and the anchorage of column longitudinal reinforcement and other structural requirements are also considered
the buried depth of foundation should be calculated from the elevation outside the room. In the area of filling and leveling, it can be calculated from the filling ground elevation, but when the filling is completed after the superstructure construction, it should be calculated from the natural ground elevation. For the basement, when the box foundation or raft foundation is used, the buried depth of the foundation is calculated from the outside elevation; When independent foundation or strip foundation is adopted, it shall be calculated from indoor ground level
extended data:
precautions:
1. The foundation should be built on a solid and reliable foundation, not on the weak soil layer with low bearing capacity and high compressibility
When there is groundwater, the water content of cohesive soil increases and the volume expands when it meets with water, which makes the bearing capacity of soil decrease. Groundwater containing erosive substances will corrode the foundation When the basement, equipment foundation or underground facilities are set up in the building, the buried depth of the foundation should meet the use requirements; The buried depth of high-rise building foundation should increase with the increase of building height to meet the stability requirements Generally, when the load is large, the buried depth of the foundation should be increased, and the foundation subjected to uplift force should have a larger buried depth to meet the requirements of uplift forcebackfill refers to the construction process of taking soil and backfilling within 5m after the completion of foundation, cushion and other concealed works
calculation rules
(1) the volume of trench and foundation pit backfill is calculated by subtracting the volume of excavation from the volume of buried objects (including foundation cushion, foundation, etc.) under the designed outdoor floor
quantity of trench and foundation pit backfill = volume of excavation - volume of foundation and cushion buried under outdoor floor
(2) backfill in the center of building is calculated by multiplying the area between main walls by the thickness of backfill. House core backfill refers to the backfill between the outdoor terrace and the indoor ground cushion, also known as indoor backfill
quantity of backfill in the center of the house = net area between the main walls
*
thickness of backfill
= (bottom floor area area occupied by the main wall) *
thickness of backfill
= (s1-l
*
thickness of outer wall - L
*
thickness of inner wall)
*
thickness of backfill
where
thickness of backfill - the distance between the outdoor floor and the indoor floor cushion .
The quantity of house core backfill = net area between main walls * backfill thickness
= (bottom floor building area - main wall area) * backfill thickness
= (s1-l middle * outer wall thickness - L inner * inner wall thickness) * backfill thickness
in the formula, backfill thickness - the distance between outdoor floor and indoor surface cushion
the volume of Earth (stone) backfill is calculated according to the design drawing
1. Site backfill: the backfill area multiplied by the average backfill thickness
2. Indoor backfill: the net area between the main walls multiplied by the backfill thickness
3. Foundation backfilling: the volume of excavation minus the volume of foundation buried below the designed outdoor floor (including foundation cushion and other structures)
4. Trench backfill: the volume of excavation minus the volume of cushion and trench with diameter greater than 200
The compaction methods generally include rolling method, tamping method, vibrating compaction method and using soil transportation tools. For large-area filling projects, rolling and soil transportation tools are often used. For the filling project with small area, the tamping tools should be used for compaction
extended data:
backfilling method:
1. Artificial filling method
The mechanical filling method generally includes bulldozer filling; Earth filling by scraper; There are three kinds of car filling Compaction methods generally include rolling, tamping and vibrating compaction, as well as the use of soil transport tools. For large-area filling projects, rolling and soil transportation tools are often used. For the filling project with small area, the tamping tools should be used for compactionprocess flow: cleaning the foundation pit (trench) floor → checking the soil quality → layering and harrowing → ramming and compacting → checking the compactness → trimming and leveling and acceptance
before filling, the garbage and other debris on the foundation pit (trench) bottom or floor shall be cleaned up; Before backfilling the fertilizer trough, it must be cleaned up to the bottom elevation of the foundation, and the falling loose garbage, mortar, stones and other debris must be removed
check whether there are impurities in the quality of the backfill, whether the particle size meets the requirements, and whether the water content of the backfill is within the control range; If the water content is too high, measures such as loosening, drying or even mixing with dry soil can be adopted; If the water content on the backfill is low, measures such as watering in advance can be adopted
earthwork backfill mainly includes foundation fill, foundation pit (trench) or pipe trench backfill, indoor floor backfill, outdoor site backfill leveling, etc. For the backfill on both sides or around and on the upper part of underground facilities (such as underground structures, ditches, pipeline ditches, etc.), the underground works shall be inspected first, and the backfill can only be carried out after the acceptance proceres
The details are as follows:
(1) the volume of trench and foundation pit backfill is calculated by subtracting the volume of excavation from the volume of buried objects (including foundation cushion, foundation, etc.) under the designed outdoor floor
the quantity of trench and foundation pit backfill = the volume of excavation - the volume of foundation and cushion buried under the outdoor floor
(2) the area between the main walls is multiplied by the thickness of backfill. House core backfill refers to the backfill between the outdoor terrace and the indoor ground cushion, also known as indoor backfill
the quantity of backfill in the center of the house = the net area between the main walls * the thickness of backfill
= (the building area of the bottom floor - the area occupied by the main wall) * the thickness of backfill
= (s1-l * the thickness of the outer wall - L * the thickness of the inner wall) * the thickness of backfill
where the thickness of backfill is the distance between the outdoor terrace and the indoor ground cushion
(3) the volume of trench backfill is calculated by subtracting the volume of pipe diameter from the volume of excavation. If the pipe diameter is less than 500mm, the volume of the pipe will not be dected; When the pipe diameter exceeds 500mm, the volume of the pipe shall be dected according to the following table
extended data:
earthwork backfilling is the filling of construction engineering, mainly including foundation filling, foundation pit (trench) or pipe trench backfilling, indoor floor backfilling, outdoor site backfilling and leveling, etc. For the backfill on both sides or around and on the upper part of underground facilities (such as underground structures, ditches, pipeline ditches, etc.), the underground works shall be inspected first, and the backfill can only be carried out after the acceptance proceres
According to the design drawing size, the calculation volume is:1. Site backfill: Backfill area multiplied by average backfill thickness
2. Indoor backfill: net area between main walls multiplied by backfill thickness
3 Foundation backfill: the volume of excavation minus the volume of foundation buried under the design outdoor floor (including foundation cushion and other structures)
backfill method:
(1) artificial fill method
(2) the mechanical filling method generally includes bulldozer filling; Earth filling by scraper; There are three kinds of car filling (3) compaction methods generally include rolling, tamping and vibrating compaction, as well as the use of soil transport tools. For large-area filling projects, rolling and soil transportation tools are often used. For the filling project with small area, the tamping tools should be used for compaction(1) division of trench and foundation pit:
the trench whose bottom width is less than 3m and whose length is more than 3 times of the trench width is defined as trench; If the trench length is less than 3 times of the trench width and the bottom area of the foundation pit is less than 20m2, it is the foundation pit
if the trench width is more than 3m and the pit bottom area is more than 20m2 as shown in the figure, it shall be calculated as earthwork excavation
(2) when slope is needed to calculate the quantities of trench excavation, foundation pit and earthwork, the budget of construction drawing should be calculated according to the construction organization design; If there is no regulation in the construction organization design, it can be calculated according to table 1. When handling the project settlement, it shall be calculated according to the concealed project records signed by Party A and Party B
table of grading coefficient 1
soil type
starting point of grading (m)
manual excavation
mechanical excavation
operation in pit
operation on pit
I The second-class soil < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br > < br / < br / < br / < br / < br / < br / < br / < br / < br / < br /
1:0.50 < br / < br /
1:0.5-0.5 < br / < br /
< br / < br /
1:0:0.50 < br /
< br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br / < br /
1:1:1:1:1:1:1:1:0 < br / < br / < br / whenthe soil types in the foundation pit are different, According to the weighted average of different types of earthwork thickness
2. When calculating the grading, the repeated quantities at the junction shall not be dected. When the original trench is used as the foundation cushion, the grading shall be calculated from the upper surface of the cushion
(3) when retaining plate is needed for trench and foundation pit excavation, its width shall be calculated according to the width of trench and foundation pit bottom as shown in the figure, which is 10cm on one side and 20cm on both sides; The area of retaining plate is calculated according to the vertical support area of groove and pit. After the retaining plate is supported, the slope shall not be calculated< (4) the working face required for foundation construction shall be calculated according to table 2
calculation table of working face width required for foundation construction Table 2
foundation material
increase working face width (mm) on each side
brick foundation
200
mortar rubble foundation
150
concrete foundation cushion formwork
concrete foundation formwork
< 300
vertical surface of foundation Make the waterproof layer
800 (waterproof layer)
(V) the length of trench excavation: the outer wall is calculated according to the length of the center line shown in the figure, the inner wall is calculated according to the length of the net long line between the bottom surfaces of the foundation shown in the figure, and the volume of the internal and external protruding parts (stacks, wall attached chimneys, etc.) is included in the earthwork of trench
(6) for the part of the quantities of manual earthwork excavation and rock cutting depth exceeding the depth specified in the sub item of consumption standard, the manual transportation shall be calculated according to the equivalent horizontal transportation distance of 7m per meter, and the manual transportation shall be increased according to the items with the transportation distance increased by 20m
(7) the depth of trench and foundation pit shall be calculated according to the depth from trench and pit bottom to outer terrace as shown in the figure; The trench shall be calculated according to the depth from trench bottom to outdoor floor as shown in the figure< (1) trench and foundation pit backfill: the backfill volume of trench and foundation pit is calculated by the volume of excavation minus the volume of embedded components (including foundation cushion, foundation, etc.) below the designed outdoor floor
(2) the area between the main walls is multiplied by the thickness of the backfill
(3) the quantity of surplus soil or borrow soil can be calculated according to the following formula:
the volume of surplus soil transported out = the total volume of excavated soil - the total volume of backfill soil
in the above formula, when the calculation result is positive, it is the volume of surplus soil transported out, and when the calculation result is negative, it is the volume of borrow soil.