Mechanical construction technology of backfilled soil

1 scope

This technology is applicable to industrial and civil building, structure, large area of flat ground, large foundation pits and trench backfill.

2 construction preparation

2.l materials and equipment:

2.1.1 gravel soils, sandy soil (agreed with the design of fine sand and silt should be made) and blast ballast, can be used as a surface filler. It's maximum size shall not exceed the thickness of each layer of the filling of the 2/3 or 3/4 (when using the vibrating roller compaction), the water should meet the requirements.

2.1.2 clays should test their water content must meet the design control, can be used.

2.1.3 saline soils generally should not be used. But the filler does not contain salt crystals, salt or salt plant roots, and in conformity with the earthwork and blasting engineering construction and acceptance specification for table 1.8 of the saline soil you can use.

2.1.4 main equipment:

2.1.4.1 ship earth-moving machinery: shovels and dump trucks, dump trucks, bulldozers, scrapers, and so on.

2.1.4.2 compaction machinery: flat ground, sheep foot roller compaction and vibratory roller.

2.1.4.3 General machinery: frog-type ramming machine or diesel, wheelbarrows, shovels (flat or angled), 2m wire, ruler, 20th, hose, etc.

2.2 operating conditions:

2.2.1 construction should be based on project characteristics, embankment soil types, density requirements, construction conditions, reasonably determine fill soil moisture control, virtual shop times such as thickness and compaction parameters important backfill project, the parameters of which should be determined through compaction test.

2.2.2 filling prior to fill base and projects completed check and acceptance, qualified to make covert inspection and acceptance procedures.

2.2.3 construction, level elevation sign layout. Large pit or Groove on the edge of every 1M nailing up horizontal chunks or in fixed buildings nearby copied standard for elevation points. Large area ground floor or every certain distance horizontally on the nail.

2.2.4 confirmed earth-moving machinery, vehicle routes, should be checked in advance and, if necessary, reinforce and widen to preparations. While programmed construction program.

3 operational processes

Process flow:

Pit on the floor at the end of cleaning up → check → stratified bedding → compacting soil testing density → →

Trim level acceptance

3.1 before the filling should be based on the soil of the caves or on the surface of roots, trash and other debris were disposed of, clean.

3.2 test soil. Test of backfill material type, size, and there is no debris, compliance, and are within the control of water content of soil if moisture content is too high, uniform can be turned loose, dry or mixed with dry soil and other measures in case of filler content is low, using measures such as sprinkler wet.

3.3 filling layer casting. Each layer of the thickness of the bedding should be based on the soil, density requirements and equipment performance. Or selection according to table 1-8.

Fill each layer of thickness of bedding and compact table 1-8

Soil compaction of each layer thickness (mm) for each compaction times (more)

Sheepfoot roller

Vibration roller compaction

Frog diesel Rammer 200~300

200~350

600~1500

200~250 6~8

8~16

6~8

3~4

When 3.4 calculation of rolling compaction, control speed, generally should not exceed the following requirements:

Flat grinding: 2km/h sheepfoot roller: 3kW/h

Vibratory roller: 2km/h

3.5 when the rolling wheel (RAM) track should overlap each other to prevent leakage or leakage pressure consolidation. Aspect is high, should fill segment. Joints shall be made in each floor slopes, grinding track overlap. About overlapping 0.5~l.0M, upper and lower joints distance should not be less than 1M.

3.6 filling beyond the base surface, should guarantee the quality of the edge compaction. After filling, such as slope finishing is not required, appropriate to fill edges width to fill 0.5M; design slope rides on and shoot, wide filling 0.2m.

3.7 in the machinery construction not rolling the filling position, manual blade filled with frog-type ramming machine or diesel hierarchical dynamic compaction-compacting.

3.8 after backfill compaction should be carried out according to specifications cutting ring sampling, measure the density of dry soil, after the meet the requirements, then a layer of bedding.

3.9 fill when fully completed, the surface should be line level, any more than the standard height, line level where less than the standard height, PuTTY-leveling and tamping.

3.10 rain, winter:

3.10.1 rain during construction of embankment, should be completed as soon as possible continuous work surfaces should not be too large, hierarchical segment-by-film basis. Important or special backfill, should be completed before the rain.

3.10.2 when rain, rain protection measures or programmes to prevent surface water from entering within the Foundation and floor, so as to avoid slope collapse or destruction of soil.

3.10.3 fill projects should not be in winter, if it is necessary at the time of construction in winter, its construction method to be determined by technical and economic comparison.

3.10.4 winter before filling, clear ice and insulation on the basement; from the filling slope within 1M shall not be used in permafrost; filling application are not frozen, not heave or permeability of Earth filling, its thickness should comply with the design requirements.

3.10.5 winter outdoor temperature-5 ° c above, fill height restriction when the average temperature is below-5 degrees Celsius, filling height should not be more than provided in table 1-9. But with rocks and sand that contains no ice (not including silt), detritus when filling, without the limitation of filling height of the table.

Winter filling height restrictions table 1-9

Average temperature (℃)-fill height (m)

-5~-10

-11~-15

-16~-20 4.5

3.5

2.5

3.10.6 backfill in winter, each layer's thickness of paving should be less 20%~25% than normal construction, frozen blocks of which shall not exceed the total fill volume: 15%; its size cannot be greater than 150mm. Puts permafrost even distribution, and laminated (RAM) it. Backfill should be carried out continuously, prevents the base-FFFF or fill layers from the cold. And anti-freezing measures in a timely manner.

4 quality criteria

4.1 project:

4.1.1 base treatment must comply with the specification for design or construction requirements.

4.1.2 the backfill soil, must comply with the specification for design or construction requirements.

4.1.3 hierarchical dynamic compaction-compacting backfill is required. Sampling to determine the quality of dry soil density, the pass rate should not be less than 90%; not qualified dry density of soil quality the minimum value difference from the design value, should not be greater than 0.08g/cm3, and should not be set. Cutting ring sampling methods and quantity should be in order.

4.2 allowable deviation, as shown in table l-10.

Backfill engineering tolerances in table 1-10

Project tolerance (mm) test method

1

2 top level

Surface roughness +0,-50

20 level or drawing a foot check

2m on foot and wedged feeler foot check

5 finished product protection

5.1 when positioning standards, axis control, standards, benchmarks, and sight rail, and shipped filled Earth without collision, nor shall rest on the Dragon door. Check these standards and should be repeated on a regular basis is correct.

5.2 night-time construction, should arrange the construction sequence, there must be adequate lighting facilities. To prevent the filling extra thick, non car directly into the Foundation pit (Groove). Large floor without restriction.

5.3 base or ditch in-situ concrete should meet certain strength, will not be affected by the Earth damage, before backfill.

6 quality problems to be noticed

6.1 without the required determination of soil dry density of soil quality: each layer should be determined after tamping of backfill soil density, in line with design requirements before casting the top soil. Test report to indicate the soil types, test date, test results and test signature. Does not meet the design requirements of the position, proper treatment and re-inspection result.

6.2 backfill sunk: virtual bedding set thickness, or in winter with large blocks of frozen soil or compacted enough times, even missed ramming, base or roots, organic matter blown debris cleaned thoroughly and other reasons, causing the Earth to sink. To this end, should earnestly implement the specifications in the construction of the relevant provisions, and to strictly check and found the problem corrected.

6.3 backfill tamping pressure is not compact: should be on proper watering in dry soil in dynamic compaction to be wet if too wet likewise tamping of backfill soil compacting there was "rubber" phenomenon, then it should be "rubber" dug up, again well be tamping soil compaction.

6.4 filling in the complicated topography, geological area, and when the high fill density requirements, measures should be taken. (Such as the drainage ditch, piles, etc), in case of filled soil loss, resulting in uneven subsidence and collapse incidents.

6.5 when filling soil to fill, according to design requirements in Foundation reinforcement and to properly handle the basement under the hard and soft, empty, old radicals, as well as dark pool, and so on.

6.6 when trench backfill, to prevent the pipe centerline displacement or damage to pipelines and artificial filling and tamping around pipe and from the piping on both sides at the same time until the pipe above 0.5M, in the case of damaged pipes, mechanical backfill and compaction can be used.

In the interface, anticorrosive insulation or cable around, use fine-grain soil backfill.

Settlement calculation of 6.7 according to design requirements should be set aside, as design requirements, according to the engineering properties, fill height, type of packing, compaction and Foundation could only wait, and construction units to identify (settlement generally do not exceed fill height of 3%).

7 quality records

This standard shall meet the following quality records:

7.1 Foundation records.

7.2 ground rod sounding record.

7.3 ground covert acceptance record.

7.4 test of backfill soil report.