A non-enclosed dewatering system and construction method for a deep foundation pit drop plate area in a water-rich area

Abstract

The present invention discloses a non-enclosed dewatering system and construction method for a deep foundation pit drop plate area in a water-rich area, belonging to the technical field of building foundation pit dewatering. The dewatering system includes a foundation pit, cast-in-place piles, a dewatering well, a blind ditch, a sump and a vertical concrete component; the foundation pit includes a drop plate area and a non-drop plate area; the cast-in-place piles include cast-in-place piles in the drop plate area and cast-in-place piles in the non-drop plate area; the dewatering well includes a drop plate area dewatering well, a drop plate area ring dewatering well, a raft plate outer dewatering well, a water level observation well and a water discharge point; the drop plate area dewatering well, the drop plate area ring dewatering well and the raft plate outer dewatering well are respectively connected to the water discharge point, and the bottom of the drop plate area ring dewatering well is opened; the blind ditch is arranged around the drop plate area and is connected to the bottom of the drop plate area ring dewatering well; the sump is arranged in the non-drop plate area, and the sump is separated from the blind ditch. The present invention does not need to set a water-stop curtain. Through the effective combination of the dewatering well, the blind ditch and the sump, the dynamic balance of foundation pit dewatering and drainage is achieved, thereby reducing the construction steps and improving the construction efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of building foundation pit dewatering, and in particular relates to a non-enclosed dewatering system and a construction method for a deep foundation pit drop plate area in a water-rich area. Background Art

[0002] When excavating deep foundation pits in areas with high groundwater levels, the aquifer will be cut off, and under the action of pressure difference, groundwater will inevitably seep into the foundation pit continuously. If the foundation pit drainage work is not carried out, the foundation pit will be flooded, the on-site construction conditions will be deteriorated, the bearing capacity of the foundation will be reduced, and the dynamic water pressure may also cause sand flow, pipe bursts and slope instability. Therefore, in order to ensure the safety of foundation pit construction, effective precipitation and drainage measures must be taken to ensure that the foundation pit remains dry during excavation, maintain the stability of a certain pit slope and the stability of the foundation pit bottom plate, and do not affect the normal use of adjacent buildings and underground pipelines.

[0003] With the rapid development of high-rise buildings, pile-raft foundations are increasingly being used for super-high-rise buildings, and the depth of the raft slabs is also increasing. The challenge currently faced is to develop an economical, effective, and rapid drainage system. For dewatering in deep foundation pits, especially under hard geological conditions, the use of support structures and water-stop curtains is inefficient, seriously affecting the construction period. Furthermore, the construction process and quality of the water-stop curtains are limited, and the dynamic balance of the foundation pit drainage cannot be guaranteed, which affects the construction quality and increases the project cost. Summary of the Invention

[0004] The purpose of the present invention is to provide a non-closed dewatering system and construction method for the deep foundation pit drop plate area in water-rich areas, so as to solve the problem that the closed dewatering system using support structures and water-stop curtains in the above-mentioned background technology has low construction efficiency and is difficult to ensure the dewatering effect.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A non-closed dewatering system for a deep foundation pit drop-slab area in a water-rich region comprises a foundation pit raft area, cast-in-place piles, a dewatering well, a blind ditch, a sump and vertical concrete components; the foundation pit raft area comprises a drop-slab area and a non-drop-slab area; the cast-in-place piles comprise cast-in-place piles in the drop-slab area and cast-in-place piles in the non-drop-slab area; the dewatering well comprises a drop-slab area dewatering well, a drop-slab area surrounding dewatering well, a raft area external dewatering well, a water level observation well and a drainage point, the drop-slab area dewatering well, the drop-slab area surrounding dewatering well and the raft area external dewatering well are respectively connected to the drainage point, and a hole is opened at the bottom of the drop-slab area surrounding dewatering well; the blind ditch is arranged around the drop-slab area and is connected to the bottom of the drop-slab area surrounding dewatering well; the sump is arranged around the drop-slab area, the sump is separated from the blind ditch and is connected to the drainage point.

[0007] Furthermore, the foundation pit raft area also includes an elevator pit area, and the elevator pit area is provided with elevator pit area cast-in-place piles and a water level observation well.

[0008] Furthermore, the dewatering wells around the drop-down plate area are evenly spaced and arranged around the drop-down plate area, and are located in the same vertical plane as the two adjacent cast-in-place piles in the non-drop-down plate area.

[0009] Furthermore, the water level observation well is also arranged in the drop plate area.

[0010] Furthermore, it also includes a ramp, which includes an inner ramp of the raft and an outer ramp of the raft.

[0011] Furthermore, the blind ditch includes a ground ring beam, a guide wall, a brick membrane, a top ring beam, an inverted filter layer, a backfill mixture layer, a water stop strip and a wire mesh; the ground ring beam is arranged around the lowering area at the bottom of the cushion layer in the lowering area; the guide wall is arranged on the top of the cushion layer in the lowering area corresponding to the ground ring beam; the brick membrane is arranged on the top of the guide wall; the top ring beam is arranged on the top of the brick membrane, and its top surface is flush with the top surface of the cushion layer in the non-lowering area; the inverted filter layer is arranged around the guide wall, and its top surface is flush with the top surface of the guide wall. The top of the filter layer is provided with a geotextile layer; the backfill mixture layer is provided on the top of the geotextile layer, and its top surface is flush with the top surface of the brick membrane, and a cushion layer of the non-drop-down area is provided on the top of the mixture layer; the water stop strip is provided along the center line of the guide wall, and its bottom is embedded in the cushion layer of the drop-down area; the steel mesh is hung at the bottom of the precipitation well in the drop-down area and contacts with the filter layer, and the precipitation well in the drop-down area corresponds to the opening of the steel mesh.

[0012] Furthermore, the total cross-sectional length of the openings at the bottom of the dewatering well in the ring dewatering plate area is not greater than 1 / 3 of the circumference of the well pipe.

[0013] Furthermore, a transfer water tank is provided between the dewatering well in the drop plate area, the dewatering well in the ring drop plate area, the dewatering well outside the raft plate and the water discharge point, and the transfer water tank is provided outside the raft plate area of the foundation pit.

[0014] A construction method for a non-enclosed dewatering system in a deep foundation pit drop plate area in a water-rich area comprises the following steps:

[0015] Step 1: Cast-in-place pile construction: Carry out cast-in-place pile construction in the raft area of the foundation pit, and then carry out post-grouting of cast-in-place piles;

[0016] Step 2: Construction of dewatering wells: Based on the location of cast-in-place piles, blind ditches, and vertical concrete components, design and optimize the positioning of dewatering wells and construct them;

[0017] Step 3: Excavation and construction of water collection pit: Excavate the earth and reserve a ramp, then excavate a blind ditch space around the drop plate area, excavate a water collection pit around the drop plate area, and separate the water collection pit and the blind ditch;

[0018] Step 4: Operation of the precipitation well and sump: Install drainage pipelines to connect the precipitation well in the drop plate area with the drainage point, the precipitation well in the ring drop plate area with the drainage point, the precipitation well outside the raft plate with the drainage point, and the sump with the drainage point;

[0019] Step 5: Construction of cushion layer and blind ditch: After the water level drops, manually clean the base layer, carry out cushion layer construction in the drop-slab area, then carry out blind ditch construction, and finally carry out cushion layer construction in the non-drop-slab area;

[0020] Step 6. Raft slab construction: Cast the raft slab in the drop-down area, then close the dewatering well in the drop-down area and the dewatering well in the drop-down area away from the elevator pit area in turn; then cast the raft slab in the non-drop-down area, then close the remaining dewatering wells in the drop-down area, and finally close the dewatering well outside the raft slab.

[0021] Furthermore, in step 5, the blind ditch construction includes the following steps:

[0022] (1) Construction of ground ring beam: a circle of ground ring beam is set under the cushion layer of the drop-slab area;

[0023] (2) Waterstop construction: bury waterstops on the cushion layer of the drop slab area along the projection position of the guide wall;

[0024] (3) Guide wall construction: tie the guide wall reinforcement and complete the concrete pouring;

[0025] (4) Construction of wire mesh: Drill holes on the drainage well in the ring-drop plate area, and then tie the wire mesh to the drainage well in the ring-drop plate area firmly;

[0026] (5) Construction of filter layer: Fill gravel along the outside of the guide wall until the top surface is flush with the top surface of the guide wall. After leveling, lay a layer of geotextile on top of it;

[0027] (6) Brick membrane masonry: Brick membrane masonry is carried out along the top of the guide wall, and then a circle of top ring beams is cast on the top of the brick membrane. The top surface of the top ring beam is flush with the top surface of the cushion layer in the non-drop slab area;

[0028] (7) Construction of backfill mixture layer: backfill the mixture on top of the geotextile until its height is flush with the top surface of the brick membrane.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention provides a non-closed dewatering system and construction method for the deep foundation pit drop plate area in water-rich areas, which can effectively solve the problem of dewatering in the deep foundation pit drop plate area in water-rich areas. There is no need to set up a water-stop curtain. Through the effective combination of dewatering wells, blind ditches and collection pits, the dynamic balance of foundation pit dewatering and drainage is achieved, which reduces the construction steps and improves the construction efficiency.

[0031] 2. The present invention provides a non-closed dewatering system and construction method for the deep foundation pit drop plate area in water-rich areas. By setting a collection pit at a location with a higher water level and separating the collection pit from a blind ditch and a dewatering well, an independent dewatering and drainage system is formed to prevent the accumulated water in the collection pit from flowing out and causing the water level in other locations to rise.

[0032] 3. The present invention provides a non-closed dewatering system and construction method for the lowering plate area of a deep foundation pit in a water-rich area. A blind ditch is set around the lowering plate area and is connected to the bottom of the dewatering well around the lowering plate area, so that the accumulated water in the blind ditch is discharged through the dewatering well around the lowering plate area. The blind ditch is used to achieve the balance of the water level in the lowering plate area, which is convenient for the management of the construction site. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the arrangement of the precipitation system involved in the present invention;

[0034] Figure 2 This is a drainage diagram of the precipitation well involved in the present invention;

[0035] Figure 3 This is a schematic diagram of the layout of the precipitation wells involved in the present invention;

[0036] Figure 4 This is a schematic diagram of the arrangement of the cast-in-place piles involved in the present invention;

[0037] Figure 5 It is a structural schematic diagram of the blind ditch involved in the present invention;

[0038] Figure 6 The diagram is a schematic diagram of the arrangement of the dewatering well and vertical concrete components involved in the present invention.

[0039] In the figure: 1 - foundation pit raft area, 101 - drop-slab area, 102 - non-drop-slab area, 103 - elevator pit area; 2 - cast-in-place piles, 201 - drop-slab area cast-in-place piles, 202 - non-drop-slab area cast-in-place piles, 203 - elevator pit area cast-in-place piles; 3 - dewatering well, 301 - drop-slab area dewatering well, 302 - dewatering well around drop-slab area, 303 - dewatering well outside raft, 304 - water level observation well, 305 - transfer water tank, 306 - water discharge point; 4 - ramp, 401 - raft inner ramp, 402 - raft outer ramp; 5 - blind ditch, 501 - ground ring beam, 502 - guide wall, 503 - brick membrane, 504 - top ring beam, 505 - filter layer, 506 - backfill mixture layer; 6 - sump; 7 - vertical concrete member. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] like Figure 1-4 As shown, the present invention provides a non-enclosed dewatering system for a deep foundation pit drop-plate area in a water-rich area, comprising a foundation pit raft area 1, cast-in-place piles 2, a dewatering well 3, a ramp 4, a blind ditch 5, a sump 6 and a vertical concrete member 7; the foundation pit raft area 1 comprises a drop-plate area 101, a non-drop-plate area 102 and an elevator pit area 103; the cast-in-place piles 2 comprise cast-in-place piles 201 in the drop-plate area, cast-in-place piles 202 in the non-drop-plate area and cast-in-place piles 203 in the elevator pit area; the dewatering well 3 comprises a drop-plate area The dewatering well 301 in the area, the dewatering well 302 in the area around the dewatering plate, the dewatering well 303 outside the raft slab, the water level observation well 304 and the discharge point 306; the ramp 4 is used for excavation of the raft slab area 1 of the foundation pit; the blind ditch 5 is arranged in the non-dewatering plate area 102 around the dewatering plate area 101 and is connected with the dewatering well 302 in the area around the dewatering plate area; the sump 6 is arranged at a position where the water level in the non-dewatering plate area 102 is higher; the vertical concrete component 7 is a building structure constructed based on the raft slab area 1 of the foundation pit.

[0042] Raft plates are provided at the bottom of both the drop-down area 101 and the non-drop-down area 102 , and cushion layers are provided at the bottom of the raft plates.

[0043] The cast-in-place piles 2 are arranged in rows at even intervals.

[0044] like Figure 6As shown, the dewatering well 3 is staggered with the cast-in-place pile 2 and the vertical concrete member 7. The dewatering well 301 in the drop-down area, the dewatering well 302 in the surrounding drop-down area, and the dewatering well 303 outside the raft slab are respectively connected to the water discharge point 306 via drainage pipelines. Preferably, a transfer water tank 305 is provided between the dewatering well 301 in the drop-down area, the dewatering well 302 in the surrounding drop-down area, the dewatering well 303 outside the raft slab, and the water discharge point 306. Depending on the actual construction situation, 0 to 3 transfer water tanks 305 are provided, and the transfer water tank 305 is located outside the raft slab area 1 of the foundation pit. Dewatering wells 301 are spaced apart in the drop-down area. Dewatering wells 302 surrounding the drop-down area are spaced apart within the non-drop-down area 102 and located in the same vertical plane as the two adjacent non-drop-down area cast-in-place piles 202, minimizing the impact on the raft slab reinforcement and concrete pouring in the drop-down area 101. Dewatering wells 303 outside the raft slab are located at a higher water level outside the raft slab area 1 of the foundation pit to minimize the impact on the raft slab reinforcement and concrete pouring in the non-drop-down area 102. Two water level observation wells 304 are preferably provided, one in the drop-down area 101 and one in the elevator pit area 103, for observing the groundwater level. Discharge points 306 are located outside the raft slab area 1 of the foundation pit, and drainage ditches are provided for subsequent drainage. The drop-down area dewatering wells 301, the dewatering wells surrounding the drop-down area 302, and the dewatering wells outside the raft slab 303 all use the same specifications and depth.

[0045] The ramp 4 includes an inner ramp 401 of the raft and an outer ramp 402 of the raft. Two inner ramps 401 of the raft are preferably provided for earth excavation. The earth excavation preferably adopts a central island excavation construction method.

[0046] like Figure 5As shown, the blind ditch 5 includes a ground ring beam 501, a guide wall 502, a brick membrane 503, a top ring beam 504, a filter layer 505, a backfill mixture layer 506, a water stop strip and a wire mesh; the ground ring beam 501 is arranged around the lowering plate area 101 at the bottom of the cushion layer of the lowering plate area 101; the guide wall 502 is arranged on the top of the cushion layer of the lowering plate area 101 corresponding to the ground ring beam 501, preferably a concrete guide wall 502, and the height of the guide wall 502 is preferably 50 0mm; the water stop strip is set along the center line of the guide wall 502, and its bottom is embedded in the cushion layer of the drop plate area 101. The water stop strip is a rubber water stop strip; the brick membrane 503 is set on the top of the guide wall 502; the top ring beam 504 is set on the top of the brick membrane 503, and the top surface of the top ring beam 504 is flush with the top surface of the cushion layer of the non-drop plate area 102; the filter layer 505 is set around the guide wall 502, and its top surface is flush with the top surface of the guide wall 502, and the bottom surface extends downward to Below the ground ring beam 501, the filter layer 505 is a pebble layer or a crushed stone layer, and a geotextile layer is set on the top of the filter layer 505; the backfill mixture layer 506 is set on the top of the geotextile layer, and its top surface is flush with the top surface of the brick membrane 503, and the top is set with the cushion layer of the non-drop plate area 102. The backfill mixture layer 506 is composed of sand and gravel, cast-in-place pile chiseled fragments, low-grade concrete and other materials; the wire mesh is hung on the ring drop plate corresponding to the filter layer 505 The bottom of the area precipitation well 302 is in contact with the filter layer 505, and the corresponding openings are opened in the ring-drop plate area precipitation well 302. The total cross-sectional length of the openings is not greater than 1 / 3 of the circumference of the well pipe of the ring-drop plate area precipitation well 302. The aperture of a single opening is 5 cm, the aperture of the wire mesh is 1 cm, and the diameter of the steel wire is 1 mm. The ring-drop plate area precipitation well 302 is connected with the blind ditch 5, so that the accumulated water in the blind ditch 5 is discharged through the ring-drop plate area precipitation well 302.

[0047] The sump 6 is connected to the discharge point 306 through a drainage pipeline, and a water pump is installed inside the sump 6. The sump 6 is separated from the blind ditch 5 by masonry walls, sandbags and concrete to form two independent internal circulation systems to prevent the accumulated water in the sump 6 from flowing into the blind ditch 5 and causing the water level in other locations to rise.

[0048] A construction method for a non-enclosed dewatering system in a deep foundation pit drop plate area in a water-rich area comprises the following steps:

[0049] Step 1, construction of bored piles 2: bored piles 2 are constructed in the foundation pit raft area 1, the bored piles 2 are arranged in rows and evenly spaced, and then post-grouting of the bored piles 2 is carried out, with the first post-grouting location being within 4m below the top elevation of the bored piles 2;

[0050] Step 2, construction of precipitation well 3: combining the positions of cast-in-place pile 2, blind ditch 5 and vertical concrete component 7, design and optimize the positioning of precipitation well 3, carry out the construction of precipitation well 301 in the drop plate area, precipitation well 302 in the ring drop plate area, precipitation well 303 outside the raft slab, water level observation well 304 and discharge point 306, the net distance between precipitation well 3 and cast-in-place pile 2 is not less than 500mm, to prevent the influence of cast-in-place pile 2 expansion on the construction of precipitation well 3, and at the same time ensure the precipitation effect, the net distance between precipitation well 3 and brick diaphragm 503 and vertical concrete component 7 is not less than 200mm;

[0051] Step 3: Excavation and Construction of Sump 6: Use the central island excavation method and reserve a ramp 4. Then, excavate a 0.8-meter-wide blind ditch 5 around the drop-off area 101. Excavate a sump 6 at a location with a higher water level and larger water output around the drop-off area 101. The sump 6 has a size of 12m x 2m. The sump 6 and the blind ditch 5 are separated by masonry walls, sandbags, and concrete to form two independent internal circulation systems. Finally, excavate a discharge point 306 and a drainage ditch outside the raft area 1 of the foundation pit.

[0052] Step 4: Operation of the precipitation well 3 and the sump 6: Install drainage pipelines, connect the precipitation well 3 to the drainage point 306, and the sump 6 to the drainage point 306 respectively. The diameter of the drainage pipeline is 110 mm. Groundwater is discharged to the drainage point 306 through the drainage pipeline, or enters the drainage point 306 after being transferred through the transfer tank 305;

[0053] Step 5: Construction of cushion layer and blind ditch 5: After the water level drops, manually clean the base layer and construct the cushion layer of the drop-slab area 101. The cushion layer thickness is 100mm. Then, construct the blind ditch 5. Then, construct the cushion layer of the non-drop-slab area 102. The construction of the blind ditch 5 includes the following steps:

[0054] (1) Construction of ground ring beam 501: A circle of 500mm high and 200mm thick ground ring beam 501 is set below the cushion layer of the drop plate area 101 at the projection position of the guide wall 502 to provide a foundation for the guide wall 502 and the structural column reinforcement. The bearing capacity of the foundation can meet the bearing requirements of the guide wall 502 and the brick membrane 503. The spacing between the structural columns is set to 3m.

[0055] (2) Waterstop construction: bury the waterstop on the cushion layer of the drop plate area 101 along the center line of the projection position of the guide wall 502;

[0056] (3) Construction of guide wall 502: Tie the steel bars of guide wall 502 and complete the concrete pouring of guide wall 502. Reserve the reinforcement of structural columns upwards in guide wall 502. The thickness of guide wall 502 is 200mm.

[0057] (4) Construction of steel wire mesh: Drill a hole with a diameter of 5 cm on the drainage well 302 in the ring-type drainage plate area corresponding to the filter layer 505, and then tie the steel wire mesh to the drainage well 302 in the ring-type drainage plate area firmly;

[0058] (5) Construction of the filter layer 505: Fill the outer side of the guide wall 502 with gravel or pebbles with a particle size of 3-5 cm until the top surface is flush with the top surface of the guide wall 502. After leveling, lay a layer of geotextile on top of it;

[0059] (6) Brick membrane 503 masonry: Brick membrane 503 is masoned along the top of the guide wall 502, and then a circle of top ring beam 504 is cast on the top of the brick membrane 503. The top surface of the top ring beam 504 is flush with the top surface of the cushion layer of the non-drop floor area 102;

[0060] (7) Construction of backfill mixture layer 506: backfill sand and gravel, cast-in-place pile chiseling debris, low-grade concrete and other materials on the top of the geotextile until its height is flush with the top surface of the brick membrane 503. Preferably, first backfill 10-20 cm thick fine sand and gravel on the top of the geotextile, and then backfill cast-in-place pile chiseling debris and low-grade concrete in a 1:1 ratio. The top of the backfill mixture layer 506 is the cushion layer of the non-drop plate area 102;

[0061] Step 6, raft slab construction: cast the raft slab of the drop-down plate area 101, and then seal the drop-down plate area dewatering well 301 and the dewatering well 302 in the drop-down plate area away from the elevator pit area 103 in turn; then cast the raft slab of the non-drop-down plate area 102, and then seal the remaining dewatering wells 302 in the drop-down plate area, and finally seal the dewatering well 303 outside the raft slab; the raft slab of the drop-down plate area 101 and the raft slab of the non-drop-down plate area 102 can be constructed in an interlaced manner.

[0062] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A non-enclosed dewatering system for deep foundation pit drop-plate areas in water-rich areas, characterized in that: The invention comprises a foundation pit raft slab area (1), cast-in-place piles (2), a dewatering well (3), a blind ditch (5), a sump (6) and a vertical concrete member (7); the foundation pit raft slab area (1) comprises a dewatering slab area (101) and a non-dewatering slab area (102); the cast-in-place piles (2) comprise cast-in-place piles (201) in the dewatering slab area and cast-in-place piles (202) in the non-dewatering slab area; the dewatering well (3) comprises a dewatering well (301) in the dewatering slab area, a dewatering well (302) in the surrounding dewatering slab area, a dewatering well (303) outside the raft slab, a water level observation well (304) and a water level observation well (305). The drainage point (306) is connected to the drainage well (301) in the drop plate area, the drainage well (302) in the ring drop plate area, and the drainage well (303) outside the raft plate. The bottom of the drainage well (302) in the ring drop plate area is opened. The blind ditch (5) is arranged around the drop plate area (101) and is connected to the bottom of the drainage well (302) in the ring drop plate area. The water collection pit (6) is arranged around the drop plate area (101). The water collection pit (6) is separated from the blind ditch (5) and is connected to the drainage point (306). The blind ditch (5) comprises a ground ring beam (501), a guide wall (502), a brick membrane (503), a top ring beam (504), an inverted filter layer (505), a backfill mixture layer (506), a water stop strip and a wire mesh; the ground ring beam (501) is arranged around the lowering plate area (101) at the bottom of the cushion layer of the lowering plate area (101); the guide wall (502) is arranged at the top of the cushion layer of the lowering plate area (101) corresponding to the ground ring beam (501); the brick membrane (503) is arranged on the top of the guide wall (502); the top ring beam (504) is arranged on the top of the brick membrane (503), and its top surface is flush with the top surface of the cushion layer of the non-lowering plate area (102); the inverted filter layer (505) is arranged around the guide wall (502) is provided, and its top surface is flush with the top surface of the guide wall (502), and its bottom surface extends downward to below the ground ring beam (501), and a geotextile layer is provided on the top of the filter layer (505); the backfill mixture layer (506) is provided on the top of the geotextile layer, and its top surface is flush with the top surface of the brick membrane (503), and a cushion layer of the non-drop plate area (102) is provided on the top of the backfill mixture layer (506); the water stop strip is provided along the center line of the guide wall (502), and its bottom is pre-buried in the cushion layer of the drop plate area (101); the steel mesh is hung at the bottom of the precipitation well (302) in the drop plate area and contacts the filter layer (505), and the precipitation well (302) in the drop plate area corresponds to the steel mesh opening.

2. The non-enclosed dewatering system for deep foundation pit drop-plate areas in water-rich areas according to claim 1 is characterized in that: The foundation pit raft area (1) further includes an elevator pit area (103), wherein the elevator pit area (103) is provided with elevator pit area cast-in-place piles (203) and a water level observation well (304).

3. The non-enclosed dewatering system for deep foundation pit drop-plate areas in water-rich areas according to claim 1 is characterized in that: The dewatering wells (302) surrounding the dewatering plate area are evenly spaced and arranged around the dewatering plate area (101), and are located in the same vertical plane as the two adjacent cast-in-place piles (202) in the non-dewatering plate area.

4. The non-enclosed dewatering system for the deep foundation pit drop plate area in water-rich areas according to claim 2 is characterized in that: The water level observation well (304) is also provided in the drop plate area (101).

5. The non-enclosed dewatering system for deep foundation pit drop-plate areas in water-rich areas according to claim 1 is characterized in that: The utility model further comprises a ramp (4), wherein the ramp (4) comprises an inner ramp (401) of the raft and an outer ramp (402) of the raft.

6. The non-enclosed dewatering system for the deep foundation pit drop plate area in water-rich areas according to claim 1 is characterized in that: The total cross-sectional length of the bottom opening of the dewatering well (302) in the ring dewatering plate area is no more than 1 / 3 of the circumference of the well pipe.

7. The non-enclosed dewatering system for deep foundation pit drop-plate areas in water-rich areas according to claim 1 is characterized in that: A transfer water tank (305) is provided between the dewatering well (301) in the drop plate area, the dewatering well (302) in the ring drop plate area, the dewatering well (303) outside the raft plate, and the water discharge point (306). The transfer water tank (305) is provided outside the foundation pit raft plate area (1).

8. The construction method of a non-enclosed dewatering system for a deep foundation pit drop plate area in a water-rich area according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1, construction of cast-in-place piles (2): construction of cast-in-place piles (2) in the foundation pit raft area (1), and then post-grouting of cast-in-place piles (2); Step 2: Construction of the dewatering well (3): Based on the positions of the cast-in-place piles (2), the blind ditch (5) and the vertical concrete components (7), the positioning of the dewatering well (3) is designed and optimized and then constructed; Step 3, earth excavation and construction of a water collection pit (6): excavate the earth and reserve a ramp (4), then excavate a blind ditch (5) space around the drop plate area (101), excavate a water collection pit (6) around the drop plate area (101), and separate the water collection pit (6) and the blind ditch (5); Step 4: Operation of the precipitation well (3) and the sump (6): Install drainage pipelines to connect the precipitation well (301) in the drop plate area with the drainage point (306), the precipitation well (302) in the ring drop plate area with the drainage point (306), the precipitation well (303) outside the raft plate with the drainage point (306), and the sump (6) with the drainage point (306); Step 5, construction of cushion layer and blind ditch (5): after the water level drops, manually clean the base layer, carry out cushion layer construction of the lowering plate area (101), then carry out blind ditch (5), and then carry out cushion layer construction of the non-lowering plate area (102); Step 6, raft slab construction: cast the raft slab of the drop-down slab area (101), then seal the drop-down slab area dewatering well (301) and the drop-down slab area dewatering well (302) away from the elevator pit area (103) in sequence; then cast the raft slab of the non-drop-down slab area (102), then seal the remaining drop-down slab area dewatering wells (302), and finally seal the dewatering well (303) outside the raft slab.

9. The construction method of a non-enclosed dewatering system for a deep foundation pit drop plate area in a water-rich area according to claim 8, characterized in that: In step 5, the construction of the blind ditch (5) includes the following steps: (1) Construction of ground ring beam (501): A ring of ground ring beam (501) is set below the cushion layer of the drop plate area (101); (2) Waterstop construction: bury the waterstop on the cushion layer of the drop plate area (101) along the projection position of the guide wall (502); (3) Construction of guide wall (502): Tie the guide wall (502) steel bars and complete the concrete pouring; (4) Construction of the steel wire mesh: a hole is opened on the dewatering well (302) in the ring-type dewatering plate area, and then the steel wire mesh is firmly tied to the dewatering well (302) in the ring-type dewatering plate area; (5) Construction of the filter layer (505): Fill the outer side of the guide wall (502) with crushed stones until the top surface is flush with the top surface of the guide wall (502). After leveling, lay a layer of geotextile on top of the top surface; (6) Brick membrane (503) masonry: brick membrane (503) is masonry along the top of the guide wall (502), and then a circle of top ring beam (504) is cast on the top of the brick membrane (503), and the top surface of the top ring beam (504) is flush with the top surface of the cushion layer of the non-drop plate area (102); (7) Construction of backfill mixture layer (506): Backfill the mixture on top of the geotextile until its height is flush with the top surface of the brick membrane (503).

Images