A foundation pit pre-dewatering partition and layer verification structure

Abstract

The utility model belongs to the technical field of building and municipal construction, and specifically discloses a pre-dewatering partitioned and layered verification structure for a foundation pit, including a foundation pit, a partition wall, a bottom-dropped waterproof curtain, a dewatering well and an observation well; the bottom-dropped waterproof curtain is arranged around the foundation pit; the foundation pit is divided into a number of verification units according to the area in the pit, and the partition wall is vertically arranged between adjacent verification units; the dewatering well includes an inner drainage well and an inner pressure relief well arranged in each verification unit; the observation well is arranged in the ground area outside the pit of each edge verification unit, including an outer drainage well and an outer pressure relief well. The utility model effectively avoids deformation of the foundation pit and improves the safety of foundation pit construction through partitioned and layered leakage verification and dewatering.

Description

Technical Field

[0001] The utility model relates to the technical field of building and municipal construction, and in particular to a foundation pit pre-dewatering partition and layer verification structure. Background Art

[0002] During the foundation pit construction, structural enclosure and regional dewatering will be carried out to ensure the safety of underground structure construction and the surrounding environment of the foundation pit. Well point dewatering is a conventional dewatering method used in existing construction. Usually, a large number of pressure relief wells and drainage wells are set up to pump water to meet the dewatering needs. At present, pre-dewatering before foundation pit excavation is relatively chaotic, which often leads to unknown deformation of the foundation pit, lacks guidance for the judgment of water-stop curtain leakage and dewatering operation, and has great safety hazards. Utility Model Content

[0003] In order to solve the above problems, the utility model provides a foundation pit pre-dewatering partition and layered verification structure, which can effectively judge the leakage of the water-stop curtain, and carry out partition and layered dewatering, thereby improving the dewatering effect and effectively avoiding foundation pit deformation.

[0004] In order to achieve the above purpose, the specific technical solutions adopted by the utility model are as follows:

[0005] A foundation pit pre-dewatering zoning and layering verification structure, comprising:

[0006] The foundation pit is divided into several verification units according to the area, and the soil layers below it include the phreatic layer, the first impermeable layer, the confined aquifer, and the second impermeable layer in sequence;

[0007] A partition wall is vertically arranged between adjacent verification units, with the bottom end located at the second waterproof layer;

[0008] A bottom-drop waterproof curtain is arranged around the foundation pit, with the bottom end located at the second waterproof layer;

[0009] A dewatering well, including an internal dewatering well and an internal dewatering well provided in each verification unit, wherein the bottom end of the internal dewatering well is located in the phreatic layer, and the bottom end of the internal dewatering well is located in the confined aquifer;

[0010] Observation wells are set up in the ground area outside the pit of each edge verification unit, including external drainage wells and external pressure relief wells. The setting depths (bottom positions) of the external drainage wells and external pressure relief wells are respectively consistent with the internal drainage wells and internal pressure relief wells in their corresponding verification units. While pumping water from the internal drainage wells and internal pressure relief wells, the water levels of the external drainage wells and external pressure relief wells at the corresponding positions outside them are monitored to seep and determine whether the bottom-drop water-stopping curtain is leaking. When there is a need for precipitation outside the foundation pit, the external drainage wells and external pressure relief wells can be used for precipitation.

[0011] Preferably, the structures of the inner drainage well and the outer drainage well include a first well pipe and a first filter material layer and a first clay ball layer filled from bottom to top between the first well pipe and the wellbore wall.

[0012] Preferably, the structures of the inner and outer pressure relief wells include a second well pipe and a second filter material layer, a second clay ball layer, and a grouting layer filled from bottom to top between the second well pipe and the wellbore wall. Compared with the drainage well, the pressure relief well has an additional grouting layer to strengthen the water stop on the side wall of the well pipe and ensure the precipitation effect.

[0013] Preferably, the bottom end of the partition wall penetrates at least 1.50m into the second waterproof layer to improve its stability. The partition wall has certain strength and water-stopping properties, and its form can be underground continuous wall, TRD method pile wall, SMW method pile wall, high-pressure rotary grouting pile wall, PC method pile wall, Larsen steel sheet pile wall, etc., and water-stopping measures can be strengthened at the joints, such as MJS method piles, high-pressure rotary grouting piles, etc.

[0014] Preferably, water level observation holes can be set inside and outside the foundation pit, and correspondingly set next to each precipitation well and drainage well, which are arranged in layers and zones like the existing precipitation wells and observation wells. The precipitation wells and drainage wells inside and outside the foundation pit have precipitation functions. When they precipitate, the internal water level is unstable. Therefore, setting a special water level observation hole next to it can more accurately and stably reflect its water level changes than direct monitoring. The structure of the water level observation hole is the same as that of the conventional foundation pit observation hole, which is composed of a plastic pipe and an end cover.

[0015] The utility model has the following beneficial effects:

[0016] 1. By dividing the verification unit in the foundation pit, setting up an observation well outside the foundation pit corresponding to each verification unit, and setting up a drainage well and a precipitation well in each verification unit, the water-stop curtain can be detected in a zoned and layered manner, which speeds up the detection of leakage, facilitates timely discovery and repair of problems, reduces the impact of leakage, improves the precipitation effect, and avoids the deformation of the foundation pit caused by leakage of the water-stop curtain.

[0017] 2. By dividing the verification units in the foundation pit, zoned and layered precipitation is achieved, and the precipitation area is gradually expanded step by step, avoiding the problem of foundation pit deformation caused by traditional large-scale blind precipitation.

[0018] 3. Use wired or wireless water level sensors to simultaneously monitor the water levels of wells set up in layers and zones inside and outside the foundation pit. Use groundwater data model verification or geophysical non-destructive testing to comprehensively determine the quality of the water-stop curtain and the foundation pit dewatering capacity, verify the rationality and feasibility of on-site water, electricity and monitoring, conduct regular drills, and promptly stop leakage before excavation if it is found. Develop a reasonable and feasible dynamic leakage control emergency plan to ensure that the anti-floating and waterproofing of the underground structure meet the regulatory requirements.

[0019] 4. Use wired or wireless water level sensors to simultaneously monitor the water levels of wells in the layered and zoned areas inside and outside the foundation pit. Utilize multiple sets of optimized combined pumping verification test methods, use groundwater data model verification or geophysical non-destructive testing to assist, comprehensively determine the effectiveness of the layered and zoned water-stop curtains, conduct skip-storage excavation, comprehensively determine the permeability and water-stop effectiveness of the artificial water-stop curtains and natural relative impermeable layers, and determine the verification of the artificial and natural water-stop structures in the pre-dewatering zones of the foundation pit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : The main view of the foundation pit pre-dewatering partition and layered verification structure described in Example 1.

[0021] Figure 2 : An overhead view of the foundation pit pre-dewatering partition and layered verification structure described in Example 1.

[0022] Figure 3 : Schematic diagram of the structure of the dewatering well in Example 1.

[0023] Figure 4 : The structural schematic diagram of the pressure relief well in Example 1.

[0024] In the figure: 1-foundation pit, 2-partition wall, 3-bottom-drop water-stop curtain, 4-internal drainage well, 5-internal pressure relief well, 6-external drainage well, 7-external pressure relief well; 11-verification unit, 41-first well pipe, 51-second well pipe, 42-first filter material layer, 52-second filter material layer, 43-first clay ball layer, 53-second clay ball layer, 54-grouting layer. Ⅰ-phreatic layer, Ⅱ-first impermeable layer, Ⅲ-confined aquifer Ⅲ, Ⅳ-second impermeable layer. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] A foundation pit pre-dewatering partition and layered verification structure, such as Figure 1-2 As shown, it includes a foundation pit 1, and the soil layers below the foundation pit include a phreatic layer I, a first impermeable layer II, a pressurized aquifer III, and a second impermeable layer IV in sequence; a bottom-drop waterproof curtain 3 is vertically arranged around the foundation pit 1, and the bottom end is located in the second impermeable layer IV; the pit of the foundation pit 1 (that is, the area enclosed by the bottom-drop waterproof curtain 3) is divided into nine verification units 11 according to the area, and the verification units 11 are separated by partition walls 2 (in this embodiment, the partition wall 2 is an underground continuous wall with a bottom end extending two meters into the second impermeable layer IV, and high-pressure rotary jet piles are provided at the joints to strengthen the waterproofing), each verification unit 11 is provided with a precipitation well, and the ground area outside the pit is provided with an observation well corresponding to each adjacent verification unit 11.

[0028] The dewatering well includes an inner drainage well 4 and an inner pressure relief well 5, the bottom of the inner drainage well 4 is located in the phreatic layer I, and the bottom of the inner pressure relief well 5 is located in the confined aquifer III. The observation well includes an outer drainage well 6 and an outer pressure relief well 7, the setting depths of the outer drainage well 6 and the outer pressure relief well 7 are respectively consistent with the inner drainage well 4 and the inner pressure relief well 5 in the corresponding verification unit 11.

[0029] The structures of the inner drainage well 4 and the outer drainage well 6 are as follows: Figure 3 As shown, it includes a first well pipe 41 and a first filter material layer 42 and a first clay ball layer 43 filled from bottom to top between the first well pipe 41 and the wellbore wall. The drainage well is sealed from the outside of the wellbore wall by the expansion of the clay balls. The structure of the inner pressure relief well 5 and the outer pressure relief well 7 is shown in FIG. Figure 4 As shown, it includes a second well pipe 51 and a second filter material layer 52, a second clay ball layer 53, and a grouting layer 54 filled between the second well pipe 51 and the wellbore wall from bottom to top. The pressure relief well is water-stopped outside the wellbore wall through the expansion of the clay balls and pressure grouting. The first well pipe 41 and the second well pipe 51 include a main pipe section, a filter pipe section, and a sedimentation pipe section from top to bottom. The filter pipe section is provided with filter holes; the first filter material layer 42 and the second filter material layer 52 are filled and set between the sedimentation pipe section and the wellbore wall; the second filter material layer 52 is entirely in the pressure-bearing aquifer III. In this embodiment, the filter material used in the first filter material layer 42 and the second filter material layer 52 is a mixture of yellow sand and gravel.

[0030] The above-mentioned pre-dewatering partitioned and layered verification structure for foundation pits effectively avoids deformation of foundation pits through partitioned and layered leakage verification and dewatering. When in use, dewatering is performed in the dewatering well in the outermost verification unit 11, and at the same time, the sensor directly monitors the water level changes in the same type of observation well outside the verification unit 11. If the water level in the observation well also drops, the water-stop curtain has leakage in this area and needs to be filled before dewatering.

[0031] This specific implementation method is only an explanation of the utility model, not a limitation of the utility model. Any changes made by those skilled in the art after reading the specification of the utility model will be protected by the patent law as long as they are within the scope of the claims of the utility model.

Claims

1. A foundation pit pre-dewatering zoning and layering verification structure, characterized by: include: A foundation pit (1), wherein the pit is divided into a plurality of verification units (11) according to the area, wherein the soil layers below the foundation pit sequentially include a phreatic layer (I), a first impermeable layer (II), a confined aquifer (III), and a second impermeable layer (IV); A partition wall (2) is vertically arranged between adjacent verification units (11), with the bottom end located at the second waterproof layer (IV); A bottom-drop waterproof curtain (3) is arranged around the foundation pit (1), with its bottom end located at the second waterproof layer (IV); A dewatering well, comprising an internal dewatering well (4) and an internal dewatering well (5) arranged in each verification unit (11), wherein the bottom end of the internal dewatering well (4) is located in the phreatic layer (I), and the bottom end of the internal dewatering well (5) is located in the confined aquifer (III); An observation well is arranged in the ground area outside the pit of each edge verification unit (11), and includes an external drainage well (6) and an external pressure relief well (7). The setting depths of the external drainage well (6) and the external pressure relief well (7) are respectively consistent with the internal drainage well (4) and the internal pressure relief well (5) in the corresponding verification unit (11).

2. The foundation pit pre-dewatering partition and layered verification structure according to claim 1 is characterized in that: The structures of the inner drainage well (4) and the outer drainage well (6) include a first well pipe (41), and a first filter material layer (42) and a first clay ball layer (43) filled from bottom to top between the first well pipe (41) and the wellbore wall.

3. The foundation pit pre-dewatering partition and layer verification structure according to claim 1 is characterized by: The structures of the inner pressure relief well (5) and the outer pressure relief well (7) include a second well pipe (51), and a second filter material layer (52), a second clay ball layer (53), and a grouting layer (54) filled from bottom to top between the second well pipe (51) and the wellbore wall.

4. The foundation pit pre-dewatering partition and layer verification structure according to claim 1 is characterized in that: The bottom end of the partition wall (2) penetrates into the second waterproof layer (IV) by at least 1.50 m.

5. The foundation pit pre-dewatering partition and layer verification structure according to claim 1 is characterized by: The partition wall (2) is an underground continuous wall, a TRD method pile wall, an SMW method pile wall, a high-pressure jet grouting pile wall, a PC method pile wall or a Larsen steel sheet pile wall.

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