Underground water regulation and control protection structure for confined water stratum foundation pit excavation

Abstract

The utility model relates to the technical field of foundation pit construction, in particular to an underground water regulation and control protection structure for confined water stratum foundation pit excavation. The underground water regulation and control protection structure for the foundation pit excavation of the confined water stratum comprises a waterproof curtain, a waterproof reinforcement permeability reducing layer, a dewatering well, a decompression well and a recharge well, the waterproof curtain is annularly arranged on the outer side of the foundation pit; the waterproof reinforcing permeability reducing layer is arranged between the bottom of the foundation pit and an underground confined aquifer; the dewatering well is arranged in the foundation pit; the relief well is arranged on the outer side of the waterproof curtain; the recharge well is arranged on the outer side of the relief well; the dewatering well and the decompression well are connected with the recharge well through pipelines and supercharging devices arranged on the pipelines. The problem that in the prior art, the risk that underground water flows into a foundation pit in the waterproof curtain is deepened can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of foundation pit construction, in particular to a groundwater regulation and protection structure for excavating a foundation pit in a pressurized water stratum. Background Art

[0002] At present, when excavating foundation pits in water-rich strata and multi-layered confined water strata, a method of combining a vertical water-stop curtain that deepens from the surface to the underground with a dewatering well is usually adopted to achieve the water-stopping effect; wherein, the water-stop curtain is set on the outside of the foundation pit; and the dewatering well is set on the inside of the foundation pit. However, when the confined water is buried deeper, deepening the water-stop curtain not only increases the project cost, but also makes the construction more difficult; if poor geology is encountered, the construction risk will also increase. In addition, before the foundation pit is excavated in layers, the water level is lowered to below the working surface through the dewatering well. As the water level in the foundation pit continues to decrease, the water level difference inside and outside the foundation pit increases. This causes the water-stop curtain to increase in horizontal deformation under the action of unloading the soil in the foundation pit and increasing water level difference inside and outside the foundation pit. When the horizontal deformation of the water-stop curtain is too large, it will face a great risk of groundwater influx into the foundation pit.

[0003] In summary, it is necessary to provide a groundwater regulation and protection structure for foundation pit excavation in pressurized water strata to solve the problem in the prior art that deepening the water-stop curtain faces the risk of groundwater gushing into the foundation pit. Utility Model Content

[0004] The utility model aims to provide a groundwater regulation and protection structure for excavating a foundation pit in a water-bearing stratum. The specific technical scheme is as follows:

[0005] A groundwater regulation and protection structure for excavating a foundation pit in a pressurized water stratum, comprising a water-stop curtain, a water-insulating reinforcement and seepage-reducing layer, a dewatering well, a pressure-reducing well and a recharge well; the water-stop curtain is circumferentially arranged on the outside of the foundation pit; the water-insulating reinforcement and seepage-reducing layer is arranged between the bottom of the foundation pit and the underground pressurized aquifer; the dewatering well is arranged in the foundation pit; the pressure-reducing well is arranged on the outside of the water-stop curtain; the recharge well is arranged on the outside of the pressure-reducing well; the dewatering well and the pressure-reducing well are connected to the recharge well through pipelines and a pressurizing device arranged on the pipelines.

[0006] Optionally, the groundwater regulation and protection structure for excavating a foundation pit in a pressurized water stratum further includes a support assembly disposed in the foundation pit; two ends of the support assembly are respectively connected to inner walls on both sides of the foundation pit.

[0007] Optionally, the support assembly includes a concrete support, and both ends of the concrete support are respectively connected to the inner walls on both sides of the foundation pit.

[0008] Optionally, the support assembly further includes a steel support, which is disposed below the concrete support and has two ends respectively connected to inner walls on both sides of the foundation pit.

[0009] Optionally, the groundwater regulation and protection structure for excavation of a foundation pit in a pressurized water stratum further includes a water sedimentation tank, which is disposed on the pipeline and upstream of the boosting device in the direction of water flow.

[0010] Optionally, the groundwater regulation and protection structure for excavation of a foundation pit in a pressurized water stratum further includes a water purification device, and the water purification device is disposed on a pipeline between the water sedimentation tank and the boosting device.

[0011] Optionally, the boosting device includes a boosting pump.

[0012] Optionally, the water-stop curtain includes a reinforced underground continuous wall and a plain concrete underground continuous wall connected from top to bottom.

[0013] Optionally, the water-proof reinforcement and seepage-reducing layer is arranged 1-2 m below the bottom of the foundation pit and more than 1 m above the pressure aquifer; the thickness of the water-proof reinforcement and seepage-reducing layer is 4-6 m.

[0014] Optionally, the permeability coefficient of the water-proof reinforcement and seepage-reducing layer is less than 10 -7 cm / s.

[0015] The application of the technical solution of the utility model has at least the following beneficial effects:

[0016] The utility model provides a groundwater regulation and protection structure for excavating a foundation pit in a confined water stratum, which can solve the problem in the prior art that deepening the water-stop curtain faces the risk of groundwater gushing into the foundation pit. Specifically, on the outside of the foundation pit, a water-stop curtain is used to bear the horizontal load of the soil outside the foundation pit and to isolate the hydraulic connection between the inside and outside of the foundation pit; on the inside of the foundation pit, a water-proof reinforcement and seepage-reducing layer is used to reduce the probability of the confined water gushing upward, thereby achieving the effect of water-proof reinforcement; a dewatering well, a pressure-reducing well, a recharging well and a booster are combined between the inside and outside of the foundation pit, and the groundwater extracted from the dewatering well and the pressure-reducing well is pressurized and injected into the recharging well through the booster, so as to replenish the soil with water on the one hand, and avoid the soil being compacted due to the drop in water level, thereby causing vertical deformation; on the other hand, the waste of groundwater is reduced, and the requirement of protecting groundwater is achieved; on the other hand, the groundwater level of the foundation pit is regulated to facilitate the excavation of the foundation pit.

[0017] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0019] Figure 1 It is a cross-sectional view of a groundwater regulation and protection structure for excavating a foundation pit in a pressurized water stratum in an embodiment of the utility model;

[0020] Figure 2 yes Figure 1 The combined structure of the dewatering well, pressure relief well and recharging well ( Figure 2 The direction of the arrow indicates the direction of water flow);

[0021] Among them, 1. Water-stop curtain, 2. Water-proof reinforcement and seepage reduction layer, 3. Dewatering well, 4. Pressure relief well, 5. Recharge well, 6. Pressurization device, 7. Support assembly, 7.1. Concrete support, 7.2. Steel support, 8. Water sedimentation box, 9. Water purification device, A. Foundation pit, B. Pressurized aquifer. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the utility model.

[0023] Example:

[0024] See also Figure 1-2 A groundwater regulation and protection structure for excavating a foundation pit in a confined water stratum, comprising a water-stop curtain 1, a water-blocking reinforcement and seepage-reducing layer 2, a precipitation well 3, a pressure-reducing well 4 and a recharging well 5; the water-stop curtain 1 is circumferentially arranged on the outside of the foundation pit A; the water-blocking reinforcement and seepage-reducing layer 2 is arranged between the bottom of the foundation pit A and the underground confined water-bearing layer B, and the permeability coefficient of the water-blocking reinforcement and seepage-reducing layer 2 is less than 10 -7 cm / s; This is because when excavating the foundation pit A, due to the continuous reduction of soil, the weight of the soil above the confined aquifer B is reduced. The confined aquifer B is very easy to surge (i.e., water surges into the foundation pit A above) due to the pressure relief, which is very dangerous. After adding the waterproof reinforcement and seepage reduction layer 2, on the one hand, the weight of the waterproof reinforcement and seepage reduction layer 2 is greater than the weight of the original soil layer, which increases the pressure on the confined aquifer B. On the other hand, the permeability coefficient of the waterproof reinforcement and seepage reduction layer 2 is much smaller than the vertical permeability coefficient of the soil at the excavation of the foundation pit A (generally greater than 10 -6cm / s), therefore, the probability of pressurized water surging upward is greatly reduced, which plays a role of water-isolating reinforcement; the dewatering well 3 is arranged in the foundation pit A, which is used to extract the submerged water (groundwater) in the foundation pit A, and lower the water level to 1-2m below the bottom of the foundation pit A, so as to facilitate the excavation of the foundation pit A; the pressure relief well 4 is arranged on the outside of the water-stop curtain 1, which is used to extract the pressurized water (groundwater) in the foundation pit A; the recharging well 5 is arranged on the outside of the pressure relief well 4; the dewatering well 3 and the pressure relief well 4 are connected to the recharging well 5 through pipelines and a booster device 6 (specifically a booster pump) arranged on the pipeline, which is used to pressurize the groundwater extracted from the dewatering well 3 and the pressure relief well 4 and inject it into the recharging well 5 through the booster device 6, on the one hand, to replenish the soil and avoid the soil being compacted due to the drop in water level and then causing vertical deformation; on the other hand, it reduces the waste of groundwater and meets the requirements of protecting groundwater; on the other hand, it regulates the groundwater level of the foundation pit A to facilitate the excavation of the foundation pit A.

[0025] It should be noted that the depth and number of the dewatering wells 3 should be determined based on the geological conditions and relevant specifications; the number, depth and recharge pressure of the recharge wells 5 should be determined based on the geological conditions and relevant specifications; generally, two pressure relief wells 4 are symmetrically arranged on both sides of the foundation pit A. The starting conditions of the pressure relief wells 4 are generally formulated based on the excavation depth of the foundation pit A and the buried depth of the pressurized water level. The pressure of the pressurized water is adjusted by controlling the pressure head of the pressurized water to prevent it from causing risks to the foundation pit A.

[0026] The groundwater regulation and protection structure for excavating a foundation pit in a pressurized water stratum also includes a support assembly 7 arranged in the foundation pit A; the two ends of the support assembly 7 are respectively connected to the inner walls on both sides of the foundation pit A, so as to strengthen the support for the inner wall of the foundation pit A and improve the stability of the foundation pit A.

[0027] The support assembly 7 includes a concrete support 7.1, and both ends of the concrete support 7.1 are respectively connected to the inner walls of both sides of the foundation pit A to ensure the supporting effect on the inner wall of the foundation pit A.

[0028] The support assembly 7 also includes a steel support 7.2, which is arranged below the concrete support 7.1, and its two ends are respectively connected to the inner walls on both sides of the foundation pit A to enhance the supporting effect on the inner wall of the foundation pit A.

[0029] The groundwater regulation and protection structure for excavation of a foundation pit in a pressurized water stratum also includes a water sedimentation tank 8 (specifically a three-stage sedimentation tank). The water sedimentation tank 8 is arranged on the pipeline and upstream of the boosting device 6 in the direction of water flow, so as to facilitate the sedimentation of the extracted groundwater and prevent impurities in the groundwater from clogging the boosting device 6.

[0030] The groundwater regulation and protection structure for excavation of a foundation pit in a pressurized water stratum also includes a water purification device 9 (specifically a conventional water purification device). The water purification device 9 is arranged on a pipeline between the water sedimentation tank 8 and the boosting device 6 to facilitate the purification of the groundwater after sedimentation and to fully avoid impurities in the groundwater from clogging the boosting device 6.

[0031] The water-stop curtain 1 includes a reinforced underground continuous wall and a plain concrete underground continuous wall (i.e., an underground continuous wall without a reinforced section) connected from top to bottom. The reinforced underground continuous wall bears the horizontal load of the soil outside the foundation pit A and also plays the role of isolating the hydraulic connection between the inside and outside of the foundation pit A; the plain concrete underground continuous wall mainly plays the role of isolating the hydraulic connection between the inside and outside of the foundation pit A.

[0032] The waterproof reinforcement and seepage reduction layer 2 is arranged 1-2m below the bottom of the foundation pit A and more than 1m above the confined aquifer B, so as to avoid the waterproof reinforcement and seepage reduction layer 2 poured during construction being too close to the confined aquifer B and causing disturbance to the confined aquifer B and the risk of water gushing; the thickness of the waterproof reinforcement and seepage reduction layer 2 is 4-6m, so as to achieve the effect of waterproof reinforcement; the depth of the bottom of the waterproof reinforcement and seepage reduction layer 2 is less than the depth of the bottom of the water-stop curtain 1, and the difference between the two is greater than 1m, so as to avoid groundwater gushing in from the outside of the foundation pit A during construction.

[0033] The operating principle of the groundwater regulation and protection structure for excavating a foundation pit in a water-confined stratum is as follows:

[0034] On the outside of foundation pit A, a water-stop curtain 1 is used to bear the horizontal load of the soil outside foundation pit A and to isolate the hydraulic connection between the inside and outside of foundation pit A; on the inside of foundation pit A, a water-proof reinforcement and seepage-reducing layer 2 is used to reduce the probability of pressurized water surging upward, thereby achieving the effect of water-proof reinforcement; a dewatering well 3, a pressure relief well 4, a recharge well 5 and a booster device 6 are combined between the inside and the outside of foundation pit A to pressurize the groundwater extracted from the dewatering well 3 and the pressure relief well 4 into the recharge well 5 through the booster device 6, so as to replenish the soil with water on the one hand and avoid the compaction of the soil due to the drop in water level, thereby preventing the occurrence of vertical deformation; on the other hand, it reduces the waste of groundwater and meets the requirements for protecting groundwater; on the other hand, it regulates the groundwater level of foundation pit A to facilitate the excavation of foundation pit A.

[0035] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A groundwater regulation and protection structure for excavating a foundation pit in a pressurized water stratum, characterized in that: The invention comprises a water-stop curtain (1), a water-blocking reinforcement and seepage-reducing layer (2), a dewatering well (3), a pressure-reducing well (4) and a recharging well (5); the water-stop curtain (1) is arranged circumferentially on the outside of a foundation pit; the water-blocking reinforcement and seepage-reducing layer (2) is arranged between the bottom of the foundation pit and an underground pressure-bearing aquifer; the dewatering well (3) is arranged in the foundation pit; the pressure-reducing well (4) is arranged on the outside of the water-stop curtain (1); the recharging well (5) is arranged on the outside of the pressure-reducing well (4); the dewatering well (3) and the pressure-reducing well (4) are connected to the recharging well (5) via pipelines and a pressure-boosting device (6) arranged on the pipelines.

2. The groundwater regulation and protection structure for excavation of a foundation pit in a confined water stratum according to claim 1, characterized in that: It also includes a support assembly (7) arranged in the foundation pit; the two ends of the support assembly (7) are respectively connected to the inner walls on both sides of the foundation pit.

3. The groundwater regulation and protection structure for excavation of a foundation pit in a confined water stratum according to claim 2, characterized in that: The support assembly (7) comprises a concrete support (7.1), and two ends of the concrete support (7.1) are respectively connected to the inner walls on both sides of the foundation pit.

4. The groundwater regulation and protection structure for excavation of a foundation pit in a confined water stratum according to claim 3, characterized in that: The support assembly (7) further comprises a steel support (7.2), wherein the steel support (7.2) is arranged below the concrete support (7.1), and the two ends of the steel support (7.2) are respectively connected to the inner walls on both sides of the foundation pit.

5. The groundwater regulation and protection structure for excavation of a foundation pit in a confined water stratum according to any one of claims 1 to 4, characterized in that: It also comprises a water settling box (8), which is arranged on the pipeline and upstream of the boosting device (6) in the direction of water flow.

6. The groundwater regulation and protection structure for excavating a foundation pit in a confined water stratum according to claim 5, characterized in that: It also comprises a water purification device (9), wherein the water purification device (9) is arranged on the pipeline between the water sedimentation tank (8) and the pressure boosting device (6).

7. The groundwater regulation and protection structure for excavating a foundation pit in a confined water stratum according to claim 5, characterized in that: The boosting device (6) comprises a boosting pump.

8. The groundwater regulation and protection structure for excavation of a foundation pit in a confined water stratum according to claim 5, characterized in that: The water-stop curtain (1) comprises a reinforced underground continuous wall and a plain concrete underground continuous wall which are connected from top to bottom.

9. The groundwater regulation and protection structure for excavating a foundation pit in a confined water stratum according to claim 5, characterized in that: The water-proof reinforcement and seepage-reducing layer (2) is arranged 1-2 m below the bottom of the foundation pit and more than 1 m above the pressure-bearing aquifer; the thickness of the water-proof reinforcement and seepage-reducing layer (2) is 4-6 m.

10. The groundwater regulation and protection structure for excavating a foundation pit in a confined water stratum according to claim 5, characterized in that: The permeability coefficient of the water-proof reinforcement and permeability-reducing layer (2) is less than 10 -7 cm / s.

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