Backfill soil containing frozen soil shall not be used within 0.5m from the bottom of the backfilled pipe trench to the top of the pipe in winter
.
5
.
During transportation, the garage shall not be parked within 2 meters from the groove edge
.
b
.
After passing the inspection, they can be put into use only if they meet the following requirements
.
Soil: it shall be screened before use, its particle size shall not be greater than 50mm, and shall not contain organic impurities and frozen soil
.
It is strictly prohibited to dump soil directly into the groove
.
3
.
Backfilling parts and requirements 1
.
The construction materials and construction waste on the working surface shall be cleaned before filling
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The fertilizer tank can be backfilled only after the foundation wall reaches a certain strength
.
The backfill work shall be carried out continuously to prevent the foundation soil or filled layer from freezing, and anti freezing measures shall be taken in time
.
10
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The water content of cohesive soil shall be inspected and can be used only when it meets the requirements of design and construction specifications
.
2 acceptance standard remarks: the paving thickness of each layer of backfill in winter shall be 20% ~ 50% less than that in normal temperature construction; The volume of frozen soil block shall not exceed 15% of the total volume of fill; The particle size shall not be greater than 150 mm
.
The upper soil can be paved only if it meets the design requirements
.
The staggered joint distance between the upper and lower layers shall not be less than 1.0m
.
After compaction of each layer, ring knife sampling shall be carried out according to the specifications, and the mass density of dry soil shall be measured in the field test
.
Prevent backfill subsidence: because the virtual paving soil exceeds the specified thickness or there are large frozen soil blocks during winter construction, or the compaction is not enough, or even the compaction is omitted, and the sundries at the pit bottom are not cleaned up, which is easy to lead to backfill subsidence, it should be prevented
.
The rammer must be installed with protective grounding or neutral connection
.
When the length width ratio is large, the backfilling length shall be a section every 15m, the joints of each layer shall be made into a stepped shape, the grinding tracks shall overlap by 0.5 ~ 1.0m, and the staggered joint distance between the upper and lower layers shall not be less than 1m
.
The plain soil shall be screened, and the lime soil with particle size not greater than 50mm shall be mixed evenly according to the design requirements
.
8
.
Backfill compaction: dry soil shall be properly watered before compaction; The backfill is too wet and not compacted, which is easy to show “rubber soil”
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During construction, attention shall be paid to protecting positioning pile, axis pile and elevation pile to prevent collision and displacement
.
When backfilling by sections, each layer at the joint shall be staggered by more than 1m
9
.
During paving and filling, frozen soil blocks shall be evenly distributed and compacted layer by layer
.
The test report shall indicate the type of soil material, layout diagram of borrow points, required dry mass density, test date, test conclusion and signature of test personnel
.
Acceptance standards and quality requirements 1
.
Material requirements 1
.
When entering the construction site, wear a safety helmet and fasten the hat belt
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After meeting the requirements, the upper layer of soil shall be paved
.
If the missing tamping or inaccurate tamping will cause the emptiness under the pipeline and cause the pipeline to break and leak, it shall be prevented
.
7
.
6
.
When the deep and shallow foundation pits are connected, the deep foundation pit shall be filled and tamped first
.
4 garage top backfill the first layer of backfill at the garage top shall be backfilled manually, leveled manually and compacted mechanically
.
Saline soil is generally unavailable
.
Construction and safety precautions 1
.
Earthwork backfilling is an important sub project in the sub project of foundation and foundation
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During night construction, the construction sequence shall be reasonably arranged and sufficient lighting facilities shall be provided to prevent over thick paving
.
Before backfilling, the foundation pit shall be checked for collapse by a specially assigned person, and the process shall be watched by a specially assigned person
.
Plain soil (locally lime soil) is used for backfilling of the project
.
Process flow base cleaning → Soil inspection → Survey and setting out → Layered soil paving → Layered compaction → Test compactness → Correction, leveling and acceptance
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Construction preparation 1 construction method rolling compaction method vibration method 2 operation conditions Process Description: the waterproof construction is completed before backfilling, and the backfilling can be carried out after passing the acceptance
.
This paper is an example of backfill construction on the high-quality project of Beijing company of China Construction Fifth Bureau
.
The motor of each rammer must be reinforced insulation or double insulation motor, and equipped with leakage protection device
.
If it is necessary to fill and tamp in sections, the junction shall be filled into a ladder shape with a height of 25cm
.
In reference to engineering practice in 2021, the core of Baidu network disk member 2 room shall be backfilled and tamped tightly: the tamping times shall not be less than three times
.
The parts that fail to meet the design requirements shall have treatment methods and retest conclusions
.
3
.
The backfilling materials must be submitted for inspection to test their water content and maximum dry density
.
The site and the second layer of earthwork shall be backfilled and transported to the earthwork backfilling part by loader and bulldozer, and leveled by loader
.
However, in construction engineering, quality management is often ignored due to factors such as rush period, which is prone to quality defects such as uncompacted backfill
.
The so-called “water tamping” method of pouring with water to sink the soil is strictly prohibited
.
The method and quantity of ring knife method for measuring compactness shall comply with the following provisions: for foundation pit and indoor fill, one group shall be sampled for each layer of 100-500 m2; The site is leveled and filled, and a group of 400-900 M2 samples are taken for each layer; For the backfilling of foundation pit and pipe trench, one group shall be sampled every 50-100 m2, but not less than one group shall be sampled for each layer, and the sampling part shall be in the lower half of each layer after compaction
.
2
.
Operators must wear insulating gloves and shoes..
.
The paving thickness of each layer of backfill in winter shall be 20% ~ 25% less than that during normal construction, in which the content of frozen soil shall not exceed 15%, and its particle size shall not be greater than 150 mm, and the particle size of backfill at normal temperature shall not be greater than 50 mm
.
5
.
However, the filler shall not contain salt crystals, salt blocks or roots of salt containing plants, and can be used if it meets the provisions of Table 1 ~ 8 in Appendix I of code for construction and acceptance of earthwork and blasting engineering
.
During backfilling, the selected construction tools shall be adjusted according to different parts
.
General tools: frog rammer, vertical rammer, trolley, shovel, 2m steel tape and rubber hose
.
when the backfill soil is deep and the area is large, the original natural soft soil and pits shall be treated to clean up the organic impurities
.
Smoking, slapstick and drunk operation are strictly prohibited
.
When it is filled to the elevation of the shallow foundation pit, it shall be filled and tamped together with the shallow foundation pit
.
The main machines and tools shall be used to transport earth moving machinery: shovel truck, dump truck, soil stacker, scraper truck and dumper
.
3
.
At this time, it should be excavated and replaced
.
The quicklime must be digested, the particle size shall not be greater than 5mm, and shall not contain too much water
.
Foundation backfilling A
.
4
.
The paving thickness of each layer shall be leveled and equal to the elevation on the pit side wall, or checked with ruler and standard rod
.
2
.
c
.
Gravel soil, sand (the use of fine and silty sand shall be approved by the design unit) and blasting stone slag can be used as filler below the surface
.
3
.
b
.
The soil shall be paved in layers, and the thickness of each layer shall be determined according to the soil quality, compactness requirements and machine performance
.
Measure the dry soil mass density of the soil as required: the density of the compacted dry soil shall be measured for each layer of backfill to test its compactness
.
4
.
Each rammer shall be equipped with two operators
.
It comprehensively interprets the key points of the process, which is worthy of reference and study
.
The backfill at the pipeline is limited by the pipeline, so it is no longer possible to use mechanical compaction, so it shall be compacted manually from below the pipeline; Manually tamp both sides of the pipeline and within 500mm above it to avoid damaging the pipeline
.
5
.
The maximum particle size shall not exceed 2 / 3 or 3 / 4 of the paving thickness of each layer (when vibratory roller is used), and the moisture content shall meet the requirements
.
It shall be tamped manually
.
The surrounding of the foundation can be backfilled evenly at the same time, so as to avoid stacking heavy objects on one side or walking heavy machinery and equipment
.
Prevent the lower part of the pipeline from being tamped and backfilled: the lower part of the pipeline shall be tamped and backfilled as required
.
Rolling machinery: flat roller, sheep foot roller and vibrating roller
.
The filling layer thickness and compaction times shall comply with the provisions of the above table
.
The rammer must be checked before each shift
.
Outside 500mm above the pipeline, mechanical compaction shall be used normally
.
The optimum moisture content (weight ratio) shall meet the requirements: Sand: 8-12%; Clay: 19-23%; Silty clay: 12-15%; Silt: 16-22%
.
One person operates the rammer and the other randomly arranges the wires
.
Tamping shall be one tamping and half tamping, connected in rows, and crossed vertically and horizontally
.
The thickness of each layer shall not exceed 20cm, and the tamping thickness shall be 15cm
.
