If it is necessary to fill and tamp in sections, the junction shall be filled into a ladder shape with a height of 25cm.
3.
General tools: frog rammer, vertical rammer, trolley, shovel, 2m steel tape and rubber hose.
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.
The staggered joint distance between the upper and lower layers shall not be less than 1.0m.
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.
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.
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”.
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.
The so-called “water tamping” method of pouring with water to sink the soil is strictly prohibited.
5.
5.
After meeting the requirements, the upper layer of soil shall be paved.
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.
The optimum moisture content (weight ratio) shall meet the requirements: Sand: 8-12%; Clay: 19-23%; Silty clay: 12-15%; Silt: 16-22%.
Acceptance standards and quality requirements 1.
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.
The thickness of each layer shall not exceed 20cm, and the tamping thickness shall be 15cm.
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.
During night construction, the construction sequence shall be reasonably arranged and sufficient lighting facilities shall be provided to prevent over thick paving.
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.
4.
6.
During transportation, the garage shall not be parked within 2 meters from the groove edge.
b.
Process flow base cleaning → Soil inspection → Survey and setting out → Layered soil paving → Layered compaction → Test compactness → Correction, leveling and acceptance.
Tamping shall be one tamping and half tamping, connected in rows, and crossed vertically and horizontally.
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.
The surrounding of the foundation can be backfilled evenly at the same time, so as to avoid stacking heavy objects or walking heavy machinery and equipment on one side.
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.
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.
When backfilling by sections, each layer at the joint shall be staggered by more than 1m.
The filling layer thickness and compaction times shall comply with the provisions of the above table.
c.
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.
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.
When the deep and shallow foundation pits are connected, the deep foundation pit shall be filled and tamped first.
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.
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.
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The main machines and tools shall be used to transport earth moving machinery: shovel truck, dump truck, soil stacker, scraper truck and dumper.
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 fertilizer tank can be backfilled only after the foundation wall reaches a certain strength.
During backfilling, the selected construction tools shall be adjusted according to different parts.
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.
It is strictly prohibited to dump soil directly into the groove.
Earthwork backfilling is an important sub project in the sub project of foundation and foundation.
The backfill parts and requirements of Baidu network disk members in the reference to engineering practice in 2021: 1.
It shall be tamped manually.
The upper soil can be paved only if it meets the design requirements.
During paving and filling, frozen soil blocks shall be evenly distributed and compacted layer by layer.
The water content of cohesive soil shall be inspected and can be used only when it meets the requirements of design and construction specifications.
3.
The parts that fail to meet the design requirements shall have treatment methods and retest conclusions..
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.
The quicklime must be digested, the particle size shall not be greater than 5mm, and shall not contain too much water.
4.
Smoking, slapstick and drunk operation are strictly prohibited.
The backfilling materials must be submitted for inspection to test their water content and maximum dry density.
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.
During construction, pay attention to protecting positioning piles, axis piles and elevation piles to prevent collision and displacement.
The construction materials and construction waste on the working surface shall be cleaned before filling.
Outside 500mm above the pipeline, mechanical compaction shall be used normally.
b.
5.
2.
Saline soil is generally unavailable.
Plain soil (locally lime soil) is used for backfilling of the project.
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.
When entering the construction site, wear a safety helmet and fasten the hat belt.
Rolling machinery: flat roller, sheep foot roller and vibrating roller.
After passing the inspection, they can be put into use only if they meet the following requirements.
8.
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.
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.
4 garage top backfill the first layer of backfill at the garage top shall be backfilled manually, leveled manually and compacted mechanically.
7.
This paper is an example of backfill construction on the high-quality project of Beijing company of China Construction Fifth Bureau.
At this time, it should be excavated and replaced.
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.
Construction and safety precautions 1.
Foundation backfilling A.
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.
Material requirements 1.
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.
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.
3.
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.
It comprehensively interprets the key points of the process, which is worthy of reference and study.
3.
