Pit-in-pit auxiliary dewatering method for foundation pit

Abstract

The invention discloses a pit-in-pit auxiliary precipitation method for a foundation pit, which comprises the following steps of: during earth excavation of the pit-in-pit, carrying out over-excavation on a base cleaning groove of the pit-in-pit for a preset depth, and excavating a confluence pit at the over-excavation pit bottom of the pit-in-pit; a permeable gravel layer is laid at the pit bottom, and the elevation of the permeable gravel layer is matched with the elevation of the designed pit bottom of the pit-in-pit; one end of a drainage pipe is arranged in the confluence pit, the middle of the drainage pipe is buried in the pit wall of the pit-in-pit, and a water pump is installed at the other end of the drainage pipe; a waterproof film layer is laid on the permeable gravel layer; and a foundation bottom plate is poured on the waterproof film layer, and when the foundation bottom plate is poured, the drainage pipe located in the foundation bottom plate is cut off and sealed. The problem that a traditional pit-in-pit dewatering scheme is high in construction cost is solved.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a method for auxiliary dewatering of a foundation pit. Background Art

[0002] At present, the dewatering effect of pits in pits cannot be guaranteed because the dewatering depth considered in the pit dewatering design is based on the construction of the foundation slab. If the dewatering effect of pits in pits is guaranteed by increasing the depth and number of drainage wells, the dewatering cost will be greatly increased.

[0003] When the precipitation effect of pits in pits such as sump pits and elevator pits does not meet the requirements, auxiliary precipitation is usually carried out by adding light well points around pits in pits such as sump pits and elevator pits. This auxiliary precipitation scheme is costly. Before the waterproofing construction of the foundation slab, the light well points need to be removed. After the light well points are removed, the water level in the pit in the pit rises rapidly, which will affect the construction of the foundation floor. Therefore, it is urgent to find a simple, efficient and low-cost auxiliary precipitation construction method for pits in pits. Summary of the invention

[0004] In order to overcome the defects of the prior art, a foundation pit-in-pit auxiliary dewatering method is now provided to solve the problem of high construction cost of the traditional pit-in-pit dewatering scheme.

[0005] In order to achieve the above object, a method for auxiliary dewatering of a foundation pit is provided, comprising the following steps:

[0006] When the earthwork of the pit in the pit is excavated, the base of the pit in the pit is over-excavated to a preset depth, and a confluence pit is excavated at the over-excavated bottom of the pit in the pit;

[0007] A permeable gravel layer is laid at the bottom of the pit, wherein the elevation of the permeable gravel layer is adapted to the elevation of the designed bottom of the pit in the pit;

[0008] One end of the drainage pipe is arranged in the confluence pit, the middle part of the drainage pipe is buried in the pit wall of the pit in the pit, and a water pump is installed at the other end of the drainage pipe;

[0009] Laying a waterproof membrane layer on the water-permeable gravel layer;

[0010] A base slab is poured on the waterproof membrane layer. When pouring the base slab, the drainage pipe located in the base slab is cut off and sealed.

[0011] Furthermore, after the drain pipe is cut off, a water stop sleeve is installed on the broken end of the drain pipe, and the water stop sleeve has a closed end and an open end. The drain pipe is inserted into the open end, and the open end extends into the soil below the foundation bottom plate.

[0012] Furthermore, a water stop ring is formed on the circumferential surface of the water stop sleeve.

[0013] Furthermore, the water-proof membrane layer is a PE film.

[0014] Furthermore, the particle size of the gravel in the permeable gravel layer is 10 to 20 mm.

[0015] Furthermore, a plurality of water-permeable holes are provided on a pipe wall at one end of the drain pipe, and a filter yarn layer is coated on one end of the drain pipe.

[0016] The beneficial effect of the present invention is that the foundation pit-in-pit auxiliary dewatering method of the present invention is to lay a permeable gravel layer at the bottom of the pit-in-pit, pre-bury a drainage pipe in the permeable gravel layer and the side wall of the pit-in-pit to the top of the side wall of the pit-in-pit, and cover the drainage pipe with a water stop sleeve on the top of the side wall of the pit-in-pit. A water pump is used for dewatering, and before the raft slab is poured with concrete, the drainage pipe is cut off at the closed end of the water stop sleeve, and the water stop sleeve is blocked, and the water stop sleeve is buried in the bottom slab concrete during the bottom slab concrete pouring process.

[0017] The foundation pit-in-pit auxiliary dewatering method of the present invention adopts a pit-in-pit water-stopping sleeve and a water pump for dewatering, and can stop dewatering before pouring the bottom slab concrete, thereby reducing the impact of groundwater on the bottom slab construction. The scheme is simple to construct and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0019] Figure 1 It is a structural schematic diagram of a foundation pit-in-pit auxiliary dewatering method according to an embodiment of the present invention.

[0020] Figure 2 It is a schematic structural diagram of a foundation pit according to an embodiment of the present invention.

[0021] Figure 3 It is a structural schematic diagram of one end of a drainage pipe according to an embodiment of the present invention.

[0022] Figure 4 It is a schematic structural diagram of a water stop sleeve according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] Reference Figures 1 to 4 As shown, the present invention provides a foundation pit-in-pit auxiliary dewatering method, comprising the following steps:

[0026] S1. When excavating the earthwork of the pit-in-pit 1, the base of the pit-in-pit 1 is cleared to over-excavate a preset depth, and a confluence pit 10 is excavated at the over-excavated bottom of the pit-in-pit 1.

[0027] When clearing the base of the pit within a pit, depending on the groundwater dewatering situation in the pit, when the dewatering height in the pit within a pit does not meet the construction requirements, over-dig 20cm when clearing the base of the pit within a pit, and dig a 40cm×40cm confluence pit with a depth of about 40cm at the lowest point of the pit within a pit.

[0028] S2. Lay a permeable gravel layer 2 at the bottom of the pit, and the elevation of the permeable gravel layer 2 is adapted to the elevation of the designed bottom of the pit 1 in the pit.

[0029] As a preferred embodiment, the particle size of the gravel in the water-permeable gravel layer 2 is 10 to 20 mm.

[0030] The gravel with a particle size of 10-20mm is laid in the foundation pit, and the laying thickness is about 20cm. The top elevation of the permeable gravel layer after laying is the bottom elevation of the pit in the pit. The gravel should be laid evenly and densely, and the surface should be flat after laying. It is strictly forbidden to mix gravel with soil during the gravel laying process.

[0031] S3. One end of the drainage pipe 3 is set in the confluence pit 10, the middle part of the drainage pipe 3 is buried in the pit wall of the pit 1, and the other end of the drainage pipe 3 is installed with a water pump 4.

[0032] As a preferred embodiment, a plurality of water-permeable holes are opened on the wall of one end of the drain pipe 3 , and one end of the drain pipe 3 is covered with a filter yarn layer 6 .

[0033] Water pump 4 is a self-priming pump. The self-priming pump water pipe adopts DN32 PVC pipe with a wall thickness of 4mm. φ8mm round holes (water permeable holes) are drilled within 0.5 meters of the end of the drainage pipe. The round holes are arranged in a plum blossom shape, with a spacing of 100mm, and a total of 5 rows are arranged. The end of the drainage pipe is wrapped with two layers of nylon window screen (filter yarn layer) within 0.6 meters, and fixed with No. 10 iron wire. The spacing of No. 10 iron wire is 100, and a total of 5 windings are made.

[0034] The ends of the drilled drainage pipes are buried in the 40cm×40cm×40cm confluence pit in the pit. The drainage pipes are arranged to the edge of the pit through the lower side of the gravel, and the drainage pipes are buried in the pit edge to the top of the pit. The other side of the water pipe extends into the foundation pit, and a self-priming pump is set at the foundation pit to reduce water.

[0035] S4. Lay a waterproof membrane layer on the permeable gravel layer 2.

[0036] As a preferred implementation, the water-barrier film layer is a PE film.

[0037] After the self-priming pump water pipe is pre-buried, PE film is laid on the upper side of the permeable gravel layer in the pit. The overlap length between the films should not be less than 10cm to prevent the concrete slurry from flowing into the stone when pouring the cushion concrete and affecting the stone permeability effect of the permeable gravel layer.

[0038] S5. Cast a foundation slab on the waterproof membrane layer. When casting the foundation slab, cut off the drainage pipe 3 located in the foundation slab and seal it.

[0039] After the drain pipe 3 is cut off, a water stop sleeve 5 is installed on the broken end of the drain pipe 3. The water stop sleeve 5 has a closed end and an open end. The drain pipe 3 is inserted into the open end, and the open end extends to the soil below the foundation bottom plate.

[0040] As a preferred embodiment, a water stop ring 51 is formed on the circumferential surface of the water stop sleeve 5 .

[0041] Insert a water stop sleeve onto the outside of the drainage pipe at the top of the pit in the pit.

[0042] The water stop sleeve is a galvanized steel pipe with a diameter of 5 cm and a length of 30 cm and a nut at one end. A water stop ring with a width of 5 cm is welded in the middle of the water stop sleeve, and the water stop ring and the water stop sleeve are fully welded on both sides.

[0043] A cushion layer is poured at the bottom of the foundation slab. The cushion layer is poured after the waterproof membrane layer is laid. When pouring the cushion layer, the open end of the water-stop sleeve should be buried in the cushion layer to ensure that the water-stop sleeve is firmly fixed. After the cushion layer is poured, only the water-stop sleeve and the self-pumping pipe outside the sleeve are exposed, and the rest of the parts are located below the cushion layer.

[0044] After the cushion layer is poured, 1:3 cement mortar is used to spread a 50mm radius arc angle around the water stop sleeve. The waterproof cover is folded up to wrap the water stop sleeve to the bottom of the water stop ring, and then sealed with asphalt paste.

[0045] After the base slab waterproofing construction is completed, ensure that the auxiliary precipitation self-priming pump can precipitate water normally, and carry out the construction of the waterproof protective layer of the foundation base slab, the base slab reinforcement binding, etc. according to the normal procedures.

[0046] One hour before pouring concrete for the base plate, remove the self-priming pump, cut off the water pipe of the self-priming pump along the closed end of the water-stop casing, pour water-swelling water-stop glue into the water-stop casing, and tighten it with a special nut and casing to seal it. During the concrete pouring process, bury the water-stop casing in the base plate concrete.

[0047] The auxiliary dewatering method for a foundation pit in a pit of the present invention comprises the following steps: laying a permeable gravel layer at the bottom of the pit in the pit, pre-burying a drainage pipe in the permeable gravel layer and the side wall of the pit in the pit to the top of the side wall of the pit in the pit, and covering the drainage pipe with a water stop sleeve on the top of the side wall of the pit in the pit. A water pump is used for dewatering, and before the raft slab is poured with concrete, the drainage pipe is cut off at the closed end of the water stop sleeve, and the water stop sleeve is blocked, and the water stop sleeve is buried in the bottom slab concrete during the bottom slab concrete pouring process.

[0048] The traditional dewatering method of the pit in the pit adopts the light well point dewatering scheme, and the construction and equipment rental costs of the light well point are high. In addition, the light well point must be removed before the foundation waterproofing construction. After the light well point is removed, the water level in the pit in the pit rises rapidly, which will affect the subsequent construction of the foundation bottom plate. The auxiliary dewatering method of the pit in the pit of the present invention adopts the pit in the pit water stop sleeve and water pump dewatering to stop dewatering before the bottom plate concrete is poured, reducing the impact of groundwater on the bottom plate construction. In addition, this scheme is simple to construct and low in cost.

[0049] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A method for auxiliary dewatering of a foundation pit, characterized in that: The following steps are involved: When the earthwork of the pit in the pit is excavated, the base of the pit in the pit is over-excavated to a preset depth, and a confluence pit is excavated at the over-excavated bottom of the pit in the pit; Laying a permeable gravel layer at the bottom of the pit, wherein the elevation of the permeable gravel layer is adapted to the elevation of the designed bottom of the pit in the pit; One end of the drainage pipe is arranged in the confluence pit, the middle part of the drainage pipe is buried in the pit wall of the pit in the pit, and a water pump is installed at the other end of the drainage pipe; Laying a waterproof membrane layer on the water-permeable gravel layer; A base slab is poured on the waterproof membrane layer. When pouring the base slab, the drainage pipe located in the base slab is cut off and sealed.

2. The foundation pit-in-pit auxiliary dewatering method according to claim 1, characterized in that: After the drainage pipe is cut off, a water-stopping sleeve is sleeved on the broken end of the drainage pipe, the water-stopping sleeve has a closed end and an open end, the drainage pipe is inserted into the open end, and the open end extends into the soil below the foundation bottom plate.

3. The foundation pit-in-pit auxiliary dewatering method according to claim 2, characterized in that: A water stop ring is formed on the circumferential surface of the water stop sleeve.

4. The foundation pit-in-pit auxiliary dewatering method according to claim 1, characterized in that: The water-proof film layer is a PE film.

5. The foundation pit-in-pit auxiliary dewatering method according to claim 1, characterized in that: The particle size of the gravel in the permeable gravel layer is 10 to 20 mm.

6. The foundation pit-in-pit auxiliary dewatering method according to claim 1, characterized in that: A plurality of water-permeable holes are provided on the pipe wall of one end of the drainage pipe, and a filter yarn layer is coated on one end of the drainage pipe.

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