Dewatering Construction Method of Deep Foundation Pit Combination Well in Confined Water-bearing Aquifer

A technology of confined aquifer and construction method, which is applied in the directions of infrastructure engineering, earthwork drilling, flushing wellbore, etc., can solve the problems of arranging more dewatering wells, etc., and achieve the effect of improving environmental friendliness and reducing engineering costs.

Active Publication Date: 2019-10-11
CHINA MCC5 GROUP CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a dewatering construction method for a deep foundation pit combination well in a pressure-bearing phreatic aquifer, to solve the problem in the prior art that more dewatering wells need to be arranged for a pressure-bearing phreatic layer during foundation pit construction, and to realize The purpose of reducing construction costs and protecting the groundwater environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] The dewatering construction method of a deep foundation pit combination well in a pressurized unconfined aquifer comprises the following steps: (a) determining the location of the drilling hole, inserting a casing at the wellhead into the soil layer, and the top of the casing is 0.2m from the ground; The soil layers are sealed by cohesive soil or grass braids; (b) install the drilling rig so that the drilling rig faces the casing and drill to the design depth, and the specific gravity of the mud during the drilling process is greater than the formation collapse pressure; Inject low-density mud and circulate the mud until the specific gravity of the mud in the well is 0.05g / cm lower than that during drilling 3 , after the returned mud does not contain any sediment, trip out the drill; (d) run the well pipe continuously to the bottom of the well, set the part of the well pipe facing the phreatic aquifer and the confined aquifer as the water filter pipe, and each section of...

Embodiment 2

[0034] In the dewatering construction method of deep foundation pit combined well in pressure-bearing unconfined aquifer, on the basis of embodiment 1, clear water is used to make mud naturally during the drilling process in step (b), and the mud proportion is controlled by ground solid control equipment. After drilling to the designed well depth in step (b), the drill pipe is lifted up by 0.5m, and the displacement is increased for in-situ punching drilling. The maximum outer diameter of the centralizer is 5 cm smaller than the diameter of the hole drilled in step (b). The mesh number of the filter pipe is 40 mesh. The filter material facing the phreatic aquifer layer is gravel; the filter material facing the confined aquifer layer is divided into an inner layer and an outer layer, wherein the inner layer is melon stone and the outer layer is gravel. The diameter of the hole drilled by the drilling rig is 300mm larger than the outer diameter of the well pipe.

Embodiment 3

[0036] On the basis of embodiment 1, the dewatering construction method for a deep foundation pit combination well in a pressurized unconfined aquifer further includes a step (h): digging a gravel blind ditch around the well head. The inner wall of the gravel blind ditch is paved with flake material, and the particle size of the flake material is 100-600 mm; the gravel blind ditch is filled with reverse filter particles, the particle size of the reverse filter particles is ≤50 mm, and the mud content is ≤ 5%, sand content ≤ 4%.

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Abstract

The invention discloses a dewatering construction method for a deep foundation pit combination well of a pressure-bearing phreatic water aquifer. Compared with a construction way which needs to simultaneously arrange a dewatering well and a water-lowering well in the prior art, the dewatering construction method has the advantages that a single well can be used to complete the technical effects which only can be reached by two wells in the conventional technology, the single well is used to complete synchronous dewatering for phreatic water aquifer and a ground layer of a pressure-bearing phreatic layer, and the purposes of reducing engineering cost and improving environment friendliness of underground water are achieved.

Description

technical field [0001] The invention relates to the field of dewatering wells, in particular to a dewatering construction method for a deep foundation pit combination well in a pressure-bearing submerged aquifer. Background technique [0002] A dewatering well is a well drilled to lower the groundwater level. After drilling, a water pump is used to extract the groundwater and reduce the water level of the groundwater. It is one of the measures to ensure the smooth construction of the foundation pit. The existing deep well dewatering technology generally selects dewatering and decompression schemes with dewatering wells or depressurization wells respectively according to the excavation depth of the foundation pit and the difference in the aquifer, that is, the dewatering well is used to reduce the phreatic water in the phreatic aquifer. Confined aquifers use step-down wells to reduce the confined water. Once a pressure-bearing submerged layer is encountered on the project si...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E02D19/10E02D19/16E21B21/00
Inventor 叶小斌张建辉杨涵林峰
Owner CHINA MCC5 GROUP CORP
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