Stratum stagnant water guide and drainage system and construction method thereof

Abstract

The invention relates to a stratum stagnant water guide and drainage system and a construction method thereof.The stratum stagnant water guide and drainage system is arranged in an underground precipitation area and comprises a precipitation well, a gas injection guide and drainage well and a water collecting well, the precipitation well is arranged around the exterior of an underground structure area to be built, a first precipitation device is arranged in the precipitation well, and stratum stagnant water is drained out of the precipitation well; a water collecting well is arranged in an underground structure area to be built, the top of the water collecting well is connected with a second dewatering device, stratum stagnant water deposited in the water collecting well is discharged out of the water collecting well, a gas injection drainage well is arranged between the dewatering well and the water collecting well, the top end of the gas injection drainage well is connected with a third dewatering device, and high-pressure air is continuously injected into the gas injection drainage well. The formation stagnant water is driven to be continuously guided and drained into the deep formation, the dewatering well and the water collecting well; the invention aims to solve the problems that the drainage time of stagnant water of a stratum is long and uncontrollable, and the improvement effect of underground soil body strength is poor, so that the implementation stability and safety of an underground capital construction structure are influenced.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a stratum water drainage system and a construction method thereof. Background Art

[0002] In recent years, with the increasing number of underground projects such as deep foundation pits of high-rise buildings, subways and urban integrated pipe corridors, groundwater control has become a prerequisite for ensuring the smooth construction of projects. At present, precipitation control methods are mainly used for underground drainage projects. Precipitation control projects can not only improve the strength of the soil itself, reduce the coefficient of soil lateral pressure, and improve the self-bearing capacity of the soil, thereby reducing the pressure on the underground support structure, but also have waterless construction conditions. It is currently the most widely used, most effective and most economical groundwater control measure.

[0003] However, affected by the sedimentary characteristics of the strata, during the implementation of the precipitation control project, there will be interlayer stagnant water with a thickness of about 0.6 to 1.0 m distributed at the interface of multiple layers of soil layers with different permeabilities, such as interlayer stagnant water between typical sections such as interlayers of silty clay and sand and gravel, and interlayers of loess and paleosol. Interlayer stagnant water can cause seepage and sand flow in the project. At present, precipitation wells or water collection wells are generally used to drain stagnant water in the strata. The prior art (CN110630270A) provides a drainage system and construction method for treating interlayer stagnant water in a dark excavated vertical shaft, in which a grouting bag is set at the bottom between the inner wall of the shaft and the primary support structure, and after the primary support structure is formed, grouting is injected into the grouting bag to form a water cut-off structure, and a drainage pipe is used above the water cut-off structure to drain the stagnant water into the water collection bucket at the bottom of the shaft. However, in the process of engineering practice, the existing stagnant water drainage system and method have the following technical problems:

[0004] 1. The driving force for drainage of stagnant water mainly comes from the water supply capacity of the soil itself: when the underground soil is sandy, stagnant water can flow out from between sand particles relatively freely and quickly. However, when the underground soil is a clay aquifer, such as loess, silty clay, paleosol or silty soil, the soil particles are relatively small. If it only relies on its own water supply capacity, it will take a long time to drain the water and the effect will be poor. It is not suitable for the design and construction principle of rapid closure of underground structures. Therefore, the drainage time is long and cannot be estimated and determined during the construction process.

[0005] 2. The excavation surface of the underground project is in an unsealed state for a long time during the drainage of stagnant water, and there is a risk of collapse or deformation: When stagnant water appears on the excavation surface during the implementation of the underground project, earthwork excavation and structural construction need to be suspended. At this time, the excavation surface of the foundation pit or the initial support structure of the tunnel is not closed yet, and it often takes 10-20 days to drain the stagnant water. During the drainage process, the underground soil will further lose water and deform under the incremental effect of effective stress, causing the excavation surface structure to continue to develop stress and deformation. If not properly controlled, it may cause the risk of tunnel collapse or deformation of ground environmental facilities;

[0006] 3. The timing of drainage of water retention is obviously delayed: Taking measures to reduce water in the project should not only meet the basic requirements of waterless excavation, but also improve the soil strength and ensure the quality of the completed structure. The existing drainage system cannot achieve the purpose of pre-controlling groundwater in areas where water retention may occur, resulting in poor construction quality and soil strength of the project structure during the specific implementation process, and failing to achieve the purpose of pre-engineering water reduction.

[0007] Therefore, it is hoped that there is a stratum water retention drainage system and a construction method thereof that can solve the problems existing in the prior art. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a stratum water drainage system and a construction method thereof, wherein precipitation wells, water collection wells and air injection drainage wells are arranged in areas requiring precipitation, and high-pressure air is utilized to drive stagnant stratum water to be continuously drained into deep strata, precipitation wells and water collection wells, aiming to solve the problems of long and uncontrollable stratum water drainage time, poor underground soil strength improvement effect, and thus affecting the stability and safety of underground infrastructure structure implementation.

[0010] (II) Technical solution

[0011] In order to achieve the above-mentioned purpose, the main technical scheme adopted by the present invention includes: providing a formation water retention drainage system, the formation water retention drainage system is arranged in the underground drainage area, the drainage system includes: a drainage well, a gas injection drainage well and a water collection well;

[0012] A dewatering well is arranged around the outside of the proposed underground structure area, a first dewatering device is arranged in the dewatering well to discharge stagnant formation water out of the dewatering well, a collection well is arranged inside the proposed underground structure area, the top of the collection well is connected to a second dewatering device to discharge stagnant formation water deposited in the collection well out of the collection well, an air injection and drainage well is arranged between the dewatering well and the collection well, the top of the air injection and drainage well is connected to a third dewatering device to continuously inject high-pressure air into the air injection and drainage well to drive the stagnant formation water to be continuously drained into the deep formation, the dewatering well and the collection well.

[0013] The present invention sets up precipitation wells, water collection wells and gas injection and drainage wells in the underground precipitation area, and uses high-pressure air to drive stagnant water in the formation to continuously migrate to deep formations, precipitation wells and water collection wells, so as to overcome the problem that during the implementation of underground engineering precipitation, stagnant water between layers in layered strata with different permeabilities cannot be quickly and smoothly drained, thereby restricting the smooth implementation of underground engineering.

[0014] Preferably, a first sandless concrete water filter pipe is sleeved in the precipitation well, and filter material is filled between the first sandless concrete water filter pipe and the precipitation well.

[0015] Preferably, the first dewatering device comprises: a submersible pump and a drainage pipe, the submersible pump is arranged at the bottom of the first sandless concrete water filter pipe, the top of the submersible pump is connected to the drainage pipe, and the stagnant formation water in the first sandless concrete water filter pipe is drained through the drainage pipe.

[0016] Preferably, a second sand concrete filter pipe and a sedimentation pipe are sequentially installed in the water collection well from top to bottom, the sedimentation pipe forms a sediment section in the water collection well, the lower section between the water collection well and the second sand concrete filter pipe is filled with filter material, and the upper section is filled with clay backfill filter material.

[0017] Preferably, the connection between the second sand concrete filter pipes is annularly sealed with a double-layer filter mesh.

[0018] Preferably, the second precipitation device comprises: a drainage pump and a sedimentation tank, one end of the drainage pump is connected to the top of the second sand concrete filter pipe, and the other end is connected to the sedimentation tank, and the stagnant formation water collected in the second sand concrete filter pipe is filtered and then drained.

[0019] Preferably, a gas injection pipeline is installed in the gas injection and drainage well, and the gas injection pipeline is filled with sand and gravel particles.

[0020] Preferably, the third precipitation device is an air pressure control device, which is connected to the top of the air injection pipeline to continuously inject stable high-pressure air into the air injection pipeline.

[0021] Preferably, the proposed underground structure is a foundation pit retaining structure or a dark tunnel supporting structure.

[0022] A construction method for a stratum water drainage system comprises the following steps:

[0023] Step S01: The drainage well is set up by drilling holes around the proposed underground structure area, the first sandless concrete water filter pipe is hoisted in the drainage well, and after the first sandless concrete water filter pipe is fixedly installed, the top pipe opening of the first sandless concrete water filter pipe is temporarily closed, and filter material is filled between the drainage well and the first sandless concrete water filter pipe. The stagnant water in the formation enters the first sandless concrete water filter pipe through the filter material, and the temporary closure of the first sandless concrete water filter pipe opening is removed, and the submersible pump is set at the bottom of the first sandless concrete water filter pipe, and the top of the submersible pump is connected to the drainage pipe;

[0024] Step S02: The water collection well is set up by drilling holes inside the proposed underground structure area, and the sedimentation pipe and the second sandless concrete filter pipe are hoisted in sequence in the water collection well. The sedimentation pipe is set at the bottom of the water collection well to form a sediment section, and a plurality of the second sand concrete filter pipes are set in each of the water collection wells. The second sand concrete filter pipes are connected by a double-layer filter mesh in an annular sealing manner. After all the second sandless concrete filter pipes are fixedly installed, the top pipe opening of the second sandless concrete filter pipe near the top of the water collection well is temporarily closed, and the lower section between the water collection well and the second sand concrete filter pipe is filled with filter material, and the upper section is filled with clay backfill filter material. The stagnant water in the formation enters the second sandless concrete filter pipe through the filter material or the clay backfill filter material, and the temporary closure of the top pipe opening of the second sandless concrete filter pipe is removed, and one end of the drainage pump is connected to the top of the second sand concrete filter pipe, and the other end of the drainage pump is connected to the sedimentation tank;

[0025] Step S03: drilling and constructing the gas injection and drainage well between the precipitation well and the water collection well, hoisting the gas injection pipeline in the gas injection and drainage well, filling the gas injection pipeline with sand and gravel particles, connecting the top of the gas injection pipeline to the air pressure control device, and backfilling and sealing the gas injection and drainage well and the gas injection pipeline with clay or cement;

[0026] Step S04: The submersible pump, the drainage pump and the air pressure control device are started simultaneously. The stagnant formation water in the first sandless concrete water filter pipe is discharged through the submersible pump and the drainage pipe in turn. The stagnant formation water collected in the second sand concrete water filter pipe is discharged to the rainwater pipe network through the drainage pump and the sedimentation tank in turn. The air pressure control device continuously injects high-pressure air into the air injection pipe, and the high-pressure air is discharged to the surroundings and bottom of the air injection pipe respectively, so as to drive the stagnant formation water to be continuously discharged to the precipitation well, the water collection well and the deep formation respectively.

[0027] (III) Beneficial effects

[0028] The beneficial effects of the present invention are as follows: the formation water retention drainage system of the present invention utilizes high-pressure air to drive the formation water retention to continuously migrate into the deep formation, the water collection well and the water retention drainage well, thereby forming an active driving force for the migration speed of the formation water retention; under the action of stable high-pressure air, the formation water retention can enter the external dewatering well arranged in the proposed underground structure area through the side wall of the dewatering well; the formation water retention can also enter the internal water collection well arranged in the proposed underground structure area through the side wall of the water collection well; the formation water retention can also penetrate the soil layer with low permeability within the water level drop range to be drained to the deep formation, thereby realizing the underground water retention drainage in advance before the start of the underground project, actively controlling the groundwater in advance, shortening the time required for formation water drainage, and effectively improving the improved strength of the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a top view of the ground water drainage system of the foundation pit type retaining structure of the present invention;

[0030] Figure 2 It is a top view of the ground water drainage system of the dark-excavated tunnel support structure of the present invention;

[0031] Figure 3 It is a longitudinal section view of the ground water drainage system of the foundation pit type retaining structure of the present invention;

[0032] Figure 4 It is a longitudinal section view of the ground water retention drainage system of the dark-excavated tunnel support structure of the present invention;

[0033] Figure 5 It is a longitudinal section view of the connection between the gas injection and drainage well and the third dewatering device of the present invention;

[0034] Figure 6 is a cross-sectional view of a water collection well of the present invention;

[0035] Figure 7 It is a longitudinal sectional view of the water collection well of the present invention.

[0036] [Reference Signs]

[0037] 1: dewatering well; 21: retaining structure of proposed foundation pit; 22: supporting structure of proposed dark-cut tunnel; 3: air injection drainage hole; 4: water collection well; 5: sand and gravel particles; 6: air injection pipeline; 7: air compressor; 8: second sandless concrete filter pipe; 9: filter material; 10: sediment section; 11: clay backfill filter material. DETAILED DESCRIPTION

[0038] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with the accompanying drawings through specific embodiments. Figure 1 The orientation is used as a reference.

[0039] The formation water retention drainage system and construction method proposed in the embodiment of the present invention are to set up a precipitation well, a water collection well and an air injection drainage well in the area where precipitation is required, and use an air compressor connected to the end of the air injection drainage well to continuously inject stable high-pressure air into the formation. The high-pressure air continuously infiltrates into the soil around the air injection drainage well, thereby forming an active driving force for the migration speed of the formation water retention. Under the action of stable high-pressure air, the formation water retention can enter the external precipitation well arranged in the proposed underground structure area through the side wall of the precipitation well, and the formation water retention can also enter the internal water collection well arranged in the proposed underground structure area through the side wall of the water collection well. The formation water retention can also penetrate the soil layer with low permeability within the water level drop range to the deep formation for drainage, thereby realizing the drainage of underground water retention in advance before the start of the underground project. The continuously injected stable high-pressure air serves as the active driving force for the drainage of formation water, which accelerates the drainage speed of the formation water retention. Drainage wells, water collection wells and gas injection and drainage wells are implemented simultaneously before the construction of underground structures, and water retention and drainage are carried out in advance to achieve advance groundwater control to achieve multiple goals such as ensuring the quality of underground engineering structure construction, soil drainage effect and improving soil strength. This avoids the risk of underground structure collapse or deformation caused by the excavation face being in an unsealed state for a long time in the prior art during water retention and drainage.

[0040] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0041] Embodiment 1:

[0042] Reference Figure 1 and Figure 3As shown, the formation water drainage system is set in the underground drainage area, including: a drainage well 1, an air injection drainage well 3 and a water collection well 4. A plurality of drainage wells 1 are respectively arranged around the periphery of the proposed foundation pit type retaining structure 21, and a first sandless concrete filter pipe is set in each drainage well 1, and filter material is filled between the first sandless concrete filter pipe and the drainage well 1. A first drainage device is arranged in the drainage well 1 to discharge the formation water out of the drainage well 1. Four water collection wells 4 are evenly arranged in the middle position of the proposed foundation pit retaining structure 21. The top of the water collection well 4 is connected to the second dewatering device to discharge the stagnant formation water deposited in the water collection well 4 out of the water collection well 4. Nine gas injection and drainage wells 3 are evenly arranged between the dewatering well 1 and the water collection well 4. The gas injection and drainage well 3 is sleeved with a stainless steel gas injection pipe 6. The gas injection pipe 6 is filled with sand and gravel particles 5. Air outlet holes are arranged around the gas injection pipe 6. The top of the gas injection and drainage well 3 is connected to the third dewatering device to continuously inject high-pressure air into the gas injection and drainage well 3. The high-pressure air drives the stagnant formation water to be continuously discharged to the deep formation, the dewatering well 1 and the water collection well 4 through the air outlet holes.

[0043] The depth of the water collection well 4 and the gas injection and drainage well 3 is greater than or equal to a distance of 1.5 m below the bottom plate of the underground structure to avoid the influence of water disturbance on the stability of the underground structure.

[0044] In an embodiment not shown in the figure, the first dewatering device includes: a submersible pump and a drainage pipe. A submersible pump is arranged at the bottom of the first sandless concrete water filter pipe, and the top of the submersible pump is connected to the drainage pipe to drain the stagnant water in the formation in the first sandless concrete water filter pipe through the drainage pipe.

[0045] In the embodiment not shown in the figure, the second precipitation device includes: a drainage pump and a sedimentation tank. One end of the drainage pump is connected to the top of the second sand concrete filter pipe, and the other end is connected to the sedimentation tank. The stagnant formation water collected in the second sand concrete filter pipe is filtered and then drained.

[0046] Reference Figure 5 As shown, the air compressor 7 is connected to the top of the air injection pipeline 6, and continuously injects stable high-pressure air into the air injection pipeline 6. The high-pressure air continuously penetrates into the soil around the air injection and drainage well 3, thereby forming an active driving force for the migration speed of stagnant water in the formation.

[0047] Reference Figure 6 and Figure 7As shown, the water collection well 4 is sequentially sleeved with a second sand concrete filter pipe 8 and a sedimentation pipe from top to bottom. The sedimentation pipe forms a sediment section 10 in the water collection well 4. The lower section between the water collection well 4 and the second sand concrete filter pipe is filled with filter material 9. The filter material 9 absorbs and blocks pollutants and ions to prevent mud, fine sand and other debris from mixing into the water collection well 4, thereby avoiding water and soil erosion caused by engineering pumping and reducing ground subsidence or engineering risks. In addition, the filter material 9 withstands the water pressure of the external stratum to prevent large-particle soil layers from invading the water collection well 4, thereby protecting the integrity of the wellbore. The upper section between the water collection well 4 and the second sand concrete filter pipe is filled with clay backfill filter material 11 to prevent the filter material layer from shifting and ensure the effectiveness of precipitation measures.

[0048] Embodiment 2:

[0049] Reference Figure 2 and Figure 4 As shown, the formation water drainage system is set in the underground drainage area, including: a drainage well 1, an air injection drainage well 3 and a water collection well 4. A plurality of drainage wells 1 are respectively arranged around the periphery of the proposed dark tunnel support structure 22, each drainage well 1 is sleeved with a first sandless concrete filter pipe, and filter material is filled between the first sandless concrete filter pipe and the drainage well 1. A first drainage device is arranged in the drainage well 1 to discharge the formation water out of the drainage well 1. Four water collection wells 4 are evenly arranged between the tunnels of the planned dark-excavated tunnel-type supporting structure 22. The top of the water collection well 4 is connected to a second dewatering device to discharge the stagnant formation water deposited in the water collection well 4 out of the water collection well 4. Nine gas injection and drainage wells 3 are evenly arranged between the dewatering well 1 and the water collection well 4. Gas injection pipes 6 are sleeved in the gas injection and drainage wells 3. The gas injection pipes 6 are filled with sand and gravel particles 5. The top of the gas injection and drainage well 3 is connected to a third dewatering device to continuously inject high-pressure air into the gas injection and drainage well 3 to drive the stagnant formation water to be continuously drained into the deep formation, the dewatering well 1 and the water collection well 4.

[0050] The depth of the water collection well 4 and the gas injection and drainage well 3 is greater than or equal to a distance of 1.5 m below the bottom plate of the underground structure to avoid the influence of water disturbance on the stability of the underground structure.

[0051] In an embodiment not shown in the figure, the first dewatering device includes: a submersible pump and a drainage pipe. A submersible pump is arranged at the bottom of the first sandless concrete water filter pipe, and the top of the submersible pump is connected to the drainage pipe to drain the stagnant water in the formation in the first sandless concrete water filter pipe through the drainage pipe.

[0052] In the embodiment not shown in the figure, the second precipitation device includes: a drainage pump and a sedimentation tank. One end of the drainage pump is connected to the top of the second sand concrete filter pipe, and the other end is connected to the sedimentation tank. The stagnant formation water collected in the second sand concrete filter pipe is filtered and then drained.

[0053] Embodiment 3:

[0054] The construction method of the stratum water drainage system includes the following steps:

[0055] Step S01: a precipitation well is set up by drilling holes outside the proposed underground structure area, a first sandless concrete filter pipe is hoisted in the precipitation well, and after the first sandless concrete filter pipe is fixedly installed, the top pipe opening of the first sandless concrete filter pipe is temporarily closed, and filter material is filled between the precipitation well and the first sandless concrete filter pipe, so that stagnant water in the formation enters the first sandless concrete filter pipe through the filter material, and the temporary closure of the first sandless concrete filter pipe opening is removed, and a submersible pump is set at the bottom of the first sandless concrete filter pipe, and the top of the submersible pump is connected to a drainage pipe;

[0056] Step S02: Locate the construction position of the water collection well in the proposed underground structure area and mark the position, then level the site and clear the debris at the marked position, drill the water collection well with a drill rig or a cone at the marked position, clean the water collection well after the well is drilled to the designed depth, measure the water collection well hole depth to meet the design requirements, and then hoist the sedimentation pipe and the second sandless concrete filter pipe in the water collection well in turn. During hoisting, adjust the center position and verticality of the well pipe. The sedimentation pipe is set at the bottom of the water collection well to form a sediment section. The sedimentation pipe is a stainless steel pipe with a length of 3.0m. Multiple second sand concrete filter pipes are set in each water collection well, and the second sand concrete filter pipes are connected by a double-layer filter mesh annular sealing. After the second sandless concrete filter pipe is fully fixed and installed, the top pipe opening of the second sandless concrete filter pipe near the top of the water collection well is temporarily closed, and the lower section between the water collection well and the second sand concrete filter pipe is filled with highly permeable sand and gravel particle filter material. The filter material uses natural round gravel with a mud content of less than or equal to 5%, and the particle size of the round gravel is 5-10mm. The upper section is filled with clay backfill filter material. The stagnant water in the formation enters the second sandless concrete filter pipe through the filter material or the clay backfill filter material. After the construction of the water collection well is completed, the drainage pipe is laid, the temporary closure of the top pipe opening of the second sandless concrete filter pipe is removed, and one end of the drainage pump is connected to the top of the second sand concrete filter pipe, and the other end of the drainage pump is connected to the sedimentation tank;

[0057] Step S03: Locate and obtain the construction position of the gas injection and drainage well between the precipitation well and the water collection well and mark the position, then level the site and remove debris at the marked position, drill a hole with a drilling rig or a pot cone at the marked position, clean the hole after drilling to the designed depth, measure the hole depth and see if it meets the design requirements, hoist the gas injection pipeline in the gas injection and drainage well, fill the gas injection pipeline with sand and gravel particles, connect the top of the gas injection pipeline to the air pressure control device, and use clay or cement to backfill and seal between the gas injection and drainage well and the gas injection pipeline;

[0058] Step S04: start the submersible pump, the drainage pump and the air pressure control device at the same time, the stagnant formation water in the first sandless concrete water filter pipe is discharged through the submersible pump and the drainage pipe in turn, the stagnant formation water collected in the second sand concrete water filter pipe is discharged to the rainwater pipe network through the drainage pump and the sedimentation tank in turn, the air pressure control device continuously injects high-pressure air into the air injection pipeline, and the high-pressure air is discharged around and below the air injection pipeline respectively, driving the stagnant formation water to be continuously discharged to the precipitation well, the water collection well and the deep formation respectively, the stable value of the air pressure injected into the air injection pipeline by the air pressure control device can be obtained by controlling the air pressure gradient indoor GDS triaxial test instrument test or by indoor model test, the stable value of the air pressure is set according to the underground soil conditions, the occurrence environment and the precipitation characteristic parameters, the stable value of the air pressure meets the requirements of driving the internal water of the underground soil and ensures that the unsaturated soil that has been drained or is above the initial groundwater level is in a stable state.

[0059] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0062] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0063] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A formation water drainage system, characterized by: The formation water retention drainage system is arranged in an underground drainage area, and the drainage system comprises: a drainage well (1), a gas injection drainage well (3) and a water collection well (4); A dewatering well (1) is arranged around the outside of the proposed underground structure area, a first dewatering device is arranged in the dewatering well (1) to discharge stagnant formation water out of the dewatering well (1), a water collecting well (4) is arranged inside the proposed underground structure area, the top of the water collecting well (4) is connected to a second dewatering device to discharge stagnant formation water deposited in the water collecting well (4) out of the water collecting well (4), an air injection and drainage well (3) is arranged between the dewatering well (1) and the water collecting well (4), the top of the air injection and drainage well (3) is connected to a third dewatering device to continuously inject high-pressure air into the air injection and drainage well (3), and drive the stagnant formation water to be continuously drained into the deep formation, the dewatering well (1) and the water collecting well (4).

2. The formation water retention drainage system according to claim 1, characterized in that: A first sandless concrete water filter pipe is sleeved in the precipitation well (1), and filter material is filled between the first sandless concrete water filter pipe and the precipitation well (1).

3. The formation water retention drainage system according to claim 2, characterized in that: The first dewatering device includes: a submersible pump and a drainage pipe. The submersible pump is arranged at the bottom of the first sandless concrete water filter pipe. The top of the submersible pump is connected to the drainage pipe to drain the stagnant water in the first sandless concrete water filter pipe through the drainage pipe.

4. The formation water retention drainage system according to claim 1, characterized in that: The water collection well (4) is provided with a second sand concrete filter pipe and a sedimentation pipe in sequence from top to bottom, the sedimentation pipe forms a sedimentation section in the water collection well (4), the lower section between the water collection well (4) and the second sand concrete filter pipe is filled with filter material, and the upper section is filled with clay backfill filter material.

5. The formation water retention drainage system according to claim 4, characterized in that: The connection between the second sand concrete filter pipes is annularly sealed with a double-layer filter mesh.

6. The formation water retention drainage system according to claim 5, characterized in that: The second precipitation device includes: a drainage pump and a sedimentation tank. One end of the drainage pump is connected to the top of the second sand concrete filter pipe, and the other end is connected to the sedimentation tank. The stagnant formation water collected in the second sand concrete filter pipe is filtered and then drained.

7. The formation water retention drainage system according to claim 1, characterized in that: The gas injection and drainage well (3) is sleeved with a gas injection pipeline, and the gas injection pipeline is filled with sand and gravel particles.

8. The formation water retention drainage system according to claim 7, characterized in that: The third precipitation device is an air pressure control device, which is connected to the top of the air injection pipeline and continuously injects stable high-pressure air into the air injection pipeline.

9. The formation water retention drainage system according to claim 1, characterized in that: The proposed underground structure is a foundation pit type retaining structure or a dark tunnel type supporting structure.

10. A construction method for a stratum water retention drainage system according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S01: The drainage well (1) is set up by drilling holes around the proposed underground structure area, the first sandless concrete water filter pipe is hoisted in the drainage well (1), and after the first sandless concrete water filter pipe is fixedly installed, the top pipe opening of the first sandless concrete water filter pipe is temporarily closed, and filter material is filled between the drainage well (1) and the first sandless concrete water filter pipe. The stagnant water in the formation enters the first sandless concrete water filter pipe through the filter material, and the temporary closure of the first sandless concrete water filter pipe opening is removed. The submersible pump is set at the bottom of the first sandless concrete water filter pipe, and the top of the submersible pump is connected to the drainage pipe; Step S02: The water collection well (4) is set up by drilling holes inside the proposed underground structure area, and the sedimentation pipe and the second sandless concrete filter pipe are hoisted in sequence in the water collection well (4). The sedimentation pipe is set at the bottom of the water collection well (4) to form a sediment section. A plurality of the second sandless concrete filter pipes are set up in each water collection well (4). The second sandless concrete filter pipes are connected by a double-layer filter mesh in an annular manner. After all the second sandless concrete filter pipes are fixedly installed, the top pipe opening of the second sandless concrete filter pipe near the top of the water collection well (4) is temporarily closed, and the lower section between the water collection well (4) and the second sandless concrete filter pipe is filled with filter material, and the upper section is filled with clay backfill filter material. The stagnant water in the formation enters the second sandless concrete filter pipe through the filter material or the clay backfill filter material. The temporary closure of the top pipe opening of the second sandless concrete filter pipe is removed, and one end of the drainage pump is connected to the top of the second sandless concrete filter pipe, and the other end of the drainage pump is connected to the sedimentation tank; Step S03: drilling and constructing the gas injection and drainage well (3) between the drainage well (1) and the water collection well (4), hoisting the gas injection pipeline in the gas injection and drainage well (3), filling the gas injection pipeline with sand and gravel particles, connecting the top of the gas injection pipeline to the air pressure control device, and backfilling and sealing the gas injection and drainage well (3) and the gas injection pipeline with clay or cement; Step S04: The submersible pump, the drainage pump and the air pressure control device are started simultaneously. The stagnant formation water in the first sandless concrete water filter pipe is discharged through the submersible pump and the drainage pipe in turn. The stagnant formation water collected in the second sand concrete water filter pipe is discharged to the rainwater pipe network through the drainage pump and the sedimentation tank in turn. The air pressure control device continuously injects high-pressure air into the air injection pipe. The high-pressure air is discharged to the surroundings and bottom of the air injection pipe respectively, driving the stagnant formation water to be continuously discharged to the precipitation well (1), the water collection well (4) and the deep formation respectively.

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