Water-rich area foundation pit dewatering well waterproof structure and construction method and application thereof

Abstract

The invention provides a water-rich area foundation pit dewatering well waterproof structure and a construction method thereof.According to the construction method, in the outer side space of the top of a well casing, the combined design of multiple layers of steel plate rings, an expansion rubber water stop belt and a waterproof layer is adopted, multiple waterproof lines are formed, and underground water is prevented from permeating from the side face and the bottom; and in the space above the top of the well casing, the precipitation well is fully filled and compacted by adopting the combined design of micro-expansive concrete, a first steel plate, a plugging material and a second steel plate. The invention further provides a method for integrating construction of the precipitation well, precipitation construction and later plugging, efficient drainage is conducted in the foundation pit construction stage, multiple waterproof structures are adopted in the main body structure construction stage, the method of combining drainage, guide, drainage and prevention is adopted, and the situation that due to the fact that underground water in a water-rich area breaks through a waterproof layer, a bottom plate leaks in the later period is avoided; and the waterproof capacity and effect of the dewatering well are enhanced, the problems of foundation pit dewatering in the water-rich area and later dewatering well waterproofing are effectively solved, and wide popularization and application prospects are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction, and specifically relates to a waterproof structure of a dewatering well in a foundation pit in a water-rich area and a construction method thereof, and also relates to the application of the waterproof structure of the dewatering well in a foundation pit in a water-rich area in a foundation pit dewatering project in a water-rich area. Background Art

[0002] With the development of urbanization, the development and utilization of underground space has been continuously increased, and the depth of foundation pits has become deeper and deeper. In the construction process of coastal cities, the demand for foundation pit dewatering has also gradually increased. The dewatering depth is often at least 0.5m lower than the bottom of the foundation pit. Therefore, the requirements for the effectiveness of dewatering wells and the waterproof structure of dewatering wells in the later stage are getting higher and higher. Although there are many waterproof construction methods for such problems, leakage still often occurs in this part in water-rich areas. If the waterproof sealing problem of dewatering wells in the later stage is not completely solved, the cost of the project in the construction process will usually increase, and it will also cause many inconveniences.

[0003] Traditional drainage well sealing measures can no longer effectively meet the application needs in water-rich areas. Therefore, the setting of drainage wells and the subsequent waterproofing structural measures of drainage wells are a major problem that needs to be solved urgently in the construction field. Summary of the invention

[0004] One of the purposes of the present invention is to provide a construction method for a waterproof structure of a foundation pit dewatering well in a water-rich area.

[0005] The second purpose of the present invention is to provide a waterproof structure for a foundation pit drainage well in a water-rich area.

[0006] The third purpose of the present invention is to provide a waterproof structure of a foundation pit dewatering well in a water-rich area for application in a foundation pit dewatering project in a water-rich area.

[0007] The technical solution adopted by the present invention to achieve one of the purposes is: to provide a construction method for a waterproof structure of a foundation pit dewatering well in a water-rich area, comprising the following steps: S1. After the foundation pit is excavated to the bottom and the dewatering well has completed the dewatering operation, backfill the dewatering well with sand and gravel to a certain height below the ground, and then pour micro-expansion concrete to the bottom of the well pipe groove; S2. After the bottom surface of the foundation pit is leveled, a water-draining plate is laid first, and then the steel pipe of the water-stop steel plate ring is inserted into the well pipe clamping groove. The outer circumference of the steel pipe of the water-stop steel plate ring is provided with several layers of serrated steel plate rings, and the bottom layer of steel plate ring is clamped on the top surface of the water-draining plate, and the gap between the two is blocked by an expansion rubber water-stop strip; S3, pouring the cushion layer, and then constructing the waterproof layer; the plane of the waterproof layer is close to the surface of the cushion layer, and the side of the waterproof layer is turned up to the bottom of the steel plate ring above the lowest steel plate ring; S4. Pour micro-expansion concrete in the steel pipe of the water-stop steel plate ring to a certain distance below the top surface of the topmost steel plate ring; pour the raft slab so that the top surface of the raft slab is flush with the top surface of the steel pipe; S5. Weld the first steel plate to the inner wall of the steel pipe to seal the slightly expansive concrete; fill the sealing material above the first steel plate, and then weld the second steel plate to the inner wall of the steel pipe to seal the sealing material, thereby completing the construction of the precipitation well waterproof structure.

[0008] The construction method of the waterproof structure of the foundation pit dewatering well in the water-rich area provided by the invention is improved on the basis of the traditional dewatering well waterproof structure, which solves the problem that the traditional dewatering well is easy to leak when used in the water-rich area, and is greatly improved in terms of applicability, which is mainly reflected in the following two aspects: On the one hand, in the outer space of the top of the well pipe, a combination design of multi-layer steel plate rings, expanded rubber waterstop and waterproof layer is adopted. On the basis of the traditional single-layer waterstop steel plate ring, multi-layer steel plate rings are added to effectively extend the infiltration path of groundwater; at the same time, an expanded rubber waterstop is set at the end where the bottom steel plate ring and the hydrophobic plate meet to effectively prevent groundwater from seeping in from the side gaps; and the waterproof layer serves as the second waterproof line of the raft area, which can block the groundwater below the cushion layer when the hydrophobic plate is damaged.

[0009] On the other hand, in the space above the top of the well pipe, a combination of micro-expansion concrete, the first steel plate, the plugging material and the second steel plate is used to fully fill the dense precipitation well. In order to prevent groundwater from penetrating the micro-expansion concrete layer, the first steel plate is set on top of it, and the plugging material is used as the second line of defense; further, a second steel plate is added above the plugging material, which greatly reduces the possibility of groundwater penetrating the multi-layer waterproof line, enhances the overall waterproof effect of the precipitation well waterproof structure, and improves construction efficiency.

[0010] Furthermore, in step S1, sand and gravel are backfilled into the precipitation well to a height of 0.8-1.2 m below the ground, and the sand and gravel are mixed with sand and stone in a mass ratio of 1:1.

[0011] Furthermore, in step S1, the well pipe groove is an annular recessed area opened on the inner wall of the top of the well pipe, the height of the well pipe groove is 10-20 cm, the inner diameter of the well pipe groove is 30-40 cm, and the outer diameter is 35-45 cm.

[0012] Furthermore, in step S2, the number of steel plate rings in the water-stop steel plate ring belt is not less than 4 layers; the ring width of the steel plate ring is 12-18 cm, the spacing between the two steel plate rings at the bottom layer is 15-25 cm, and the spacing between the remaining steel plate rings is 8-12 cm. The multiple layers of steel plate rings around the steel pipe above the well pipe form a zigzag shape, which can effectively extend the water seepage path.

[0013] Furthermore, in step S3, the waterproof layer is made of SBS modified asphalt waterproof membrane with a thickness of 4-6 mm.

[0014] Furthermore, in step S4, the distance between the top surface of the slightly expansive concrete in the water-stop steel plate ring and the top surface of the steel pipe is 0.15-0.25 m.

[0015] Furthermore, in step S5, the filling height of the plugging material is 15-20 cm; the plugging material is watertight SQ404.

[0016] Furthermore, in step S5, the height of the top surface of the second steel plate is kept consistent with the height of the top surface of the raft plate.

[0017] The technical solution adopted by the present invention to achieve the second purpose is: to provide a waterproof structure of a foundation pit dewatering well in a water-rich area, which is constructed by the construction method described in one of the purposes of the present invention.

[0018] The waterproof structure of the water-rich area foundation pit dewatering well includes: a water-stop steel plate ring, a sand and gravel layer, a slightly expansive concrete layer, a first steel plate, a second steel plate, a plugging material layer, a hydrophobic plate, a cushion layer, a waterproof layer, a raft plate and an expansive rubber waterstop; The waterstop steel plate ring comprises a steel pipe and several layers of steel plate rings distributed in a zigzag shape on the outer circumference of the steel pipe; the bottom of the steel pipe is inserted into the well pipe clamping groove, and the internal space formed by the steel pipe and the well pipe is a sand and gravel layer and a slightly expansive concrete layer from bottom to top, and a first steel plate and a second steel plate are arranged on the top of the slightly expansive concrete layer, and the edges of the first steel plate and the second steel plate are respectively fixedly connected to the inner wall of the steel pipe, and a sealing material layer is arranged between the two; the periphery of the waterstop steel plate ring is provided with a hydrophobic plate, a cushion layer, a waterproof layer and a raft plate from bottom to top; the bottommost steel plate ring of the waterstop steel plate ring is clamped on the top surface of the hydrophobic plate, and an expansive rubber waterstop strip is arranged in the external gap between the two.

[0019] Furthermore, the hydrophobic plate is an arched sandwich plate made of plastic, the bottom of which is a hollow arch for drainage, and the upper part is dense and has a corresponding pressure-bearing capacity.

[0020] Furthermore, the cushion layer is a plain concrete layer, which is laid after the waterstop steel plate ring and the expansion rubber waterstop strip are installed; the waterproof layer is laid after the cushion layer is completed and hardened, with the flat surface close to the cushion layer, and the side of the waterstop steel plate ring is turned up to the bottom of the second steel plate ring; the raft slab is made of reinforced concrete after the waterproof layer is completed.

[0021] Furthermore, the micro-expansive concrete layer uses micro-expansive concrete with a quick-setting effect, and is filled with well pipes and rafts to 0.15-0.25m below the top surface of the raft, and is sealed by welding with a first steel plate, and then filled with a sealing material, and then welded with a second steel plate, and the top surface height of the second steel plate is consistent with the top surface of the raft. Preferably, the sealing material is SQ404, which is watertight.

[0022] The present invention arranges a sand and gravel layer at the bottom of the well pipe and arranges a hydrophobic plate outside the well pipe. The gaps between the sand and gravel and the hydrophobic space of the hydrophobic plate can maintain the balance of groundwater pressure, and can slowly infiltrate and circulate below the cushion layer, thereby reducing the risk of leakage caused by breaking through the cushion layer due to the action of groundwater pressure.

[0023] The waterproof structure of the precipitation well in the water-rich area foundation pit provided by the present invention has a simple overall structure, and can effectively solve the problem of waterproofing the precipitation well in the water-rich area foundation pit in the later stage. A multi-layer waterproof structure is adopted in the main structure construction stage to avoid the later bottom plate leakage caused by the abundant groundwater in the water-rich area breaking through the waterproof layer, effectively enhance the waterproof capacity of the precipitation well, and have a significant waterproof effect.

[0024] The technical solution adopted by the present invention to achieve the third purpose is: to provide an application of the waterproof structure of the water-rich area foundation pit dewatering well according to the second purpose of the present invention in the water-rich area foundation pit dewatering project.

[0025] Furthermore, the application comprises the following steps: A1. Dig the wellhead of the precipitation well; A2. Lower a sandless concrete well pipe into the wellhead; a filter screen is provided below the sandless concrete well pipe; A3. Temporarily fix the sandless concrete well pipe, and evenly fill the filter material on both sides symmetrically until a certain height below the ground; then fill the clay until it is flush with the ground; A4. Connect the outlet pipe to the submersible pump and lower the submersible pump to the bottom of the filter; A5. When the water level rises to the position above the water inlet of the submersible pump, water is pumped and discharged to the designated location to complete the precipitation operation of the precipitation well; A6. After the foundation pit is excavated to the bottom and the dewatering well has completed the dewatering operation, the waterproof structure of the dewatering well in the foundation pit in the water-rich area is constructed according to the construction method of steps S1-S5.

[0026] The precipitation well provided by the present invention is composed of a sandless concrete well pipe, a filter screen, a filter material, a submersible pump, clay and a water outlet pipe. The sandless concrete well pipe is a well pipe made of pure cement and gravel, and a well pipe clamping groove is reserved on the top. The well pipe clamping groove matches the depth of the steel pipe insertion of the water-stop steel plate ring in the later waterproof structure and the height of the first annular steel plate.

[0027] Furthermore, standard filter material is used as the filter material, which is filled from the bottom of the outside of the well pipe to a height of 1.8-2.2m below the top, and the remaining part of the top is filled with clay; the filter screen is set at a height of 1.5-2.5m above the bottom of the well pipe, and the submersible pump is placed at the bottom of the filter screen and connected to the outlet pipe.

[0028] In step A2, through the design of filter material and sandless concrete well pipe, groundwater can be effectively filtered, impurities and soil are blocked outside the well pipe, and the groundwater that penetrates into the well pipe is relatively clear and can be reasonably reused according to actual needs on site, which can reduce the cost of engineering water.

[0029] The water-rich area precipitation well provided by the present invention has a simple overall structure and good water permeability, is advantageous for filtering groundwater and extracting it for repeated use, and has a good precipitation effect.

[0030] Furthermore, the present invention combines foundation pit dewatering in water-rich areas with waterproofing of subsequent dewatering wells, achieves efficient drainage during the foundation pit construction phase, and adopts a multi-layer waterproofing structure during the main structure construction phase, thereby avoiding subsequent bottom plate leakage caused by abundant groundwater breaking through the waterproof layer, effectively enhancing the waterproofing capacity of dewatering wells, and achieving a significant waterproofing effect.

[0031] Compared with the prior art, the present invention has the following beneficial effects: (1) The waterproof structure of the dewatering well in the water-rich area provided by the present invention and its construction method adopt a combination design of a multi-layer steel plate ring, an expanded rubber waterstop and a waterproof layer in the top outer space of the well pipe. On the basis of the traditional waterstop steel plate ring, a plurality of steel plate rings are added to effectively extend the penetration path of groundwater. At the same time, an expanded rubber waterstop is arranged at the end where the bottom steel plate ring and the hydrophobic plate meet to effectively prevent groundwater from seeping in from the side gaps. The waterproof layer serves as the second waterproof line of the raft area, which can block the groundwater below the cushion layer when the hydrophobic plate is damaged.

[0032] (2) The waterproof structure of the water-rich area foundation pit dewatering well and the construction method thereof provided by the present invention adopt a combination design of micro-expansion concrete, a first steel plate, a plugging material and a second steel plate in the space above the top of the well pipe to fully fill the dewatering well. In order to prevent groundwater from penetrating the micro-expansion concrete layer, a first steel plate is set on the top of it, and the plugging material is used to block it as the second line of defense; further, a second steel plate is added above the plugging material, which greatly reduces the possibility of groundwater penetrating the multi-layer waterproof line, enhances the overall waterproof effect of the dewatering well waterproof structure, and improves construction efficiency.

[0033] (3) The waterproof structure of the dewatering well in the foundation pit in the water-rich area provided by the present invention is applied to the dewatering project of the foundation pit in the water-rich area. It adopts an overall design to form a complete system from the construction and use of the dewatering well to the later sealing. It also makes a breakthrough in the efficiency and cost of traditional construction for the first time, avoiding the problem of later leakage caused by poor sealing effect of the dewatering well. It adopts a design of multiple waterproof lines and adds drainage measures. The method of combining dredging, guiding, draining and prevention is adopted to achieve remarkable waterproof effect, improve construction efficiency and reduce cost. It has broad prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1A schematic structural diagram of a waterproof structure for a water-rich area foundation pit dewatering well provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a water-rich area foundation pit dewatering well provided by an embodiment of the present invention; Among them, 1-waterstop steel plate ring; 2-sand and gravel layer; 3-micro-expansive concrete layer; 4-first steel plate; 5-second steel plate; 6-sealing material layer; 7-hydrophobic plate; 8-cushion; 9-waterproof layer; 10-raft; 11-expanding rubber waterstop; 12-steel pipe; 13-steel plate ring; 14-well pipe slot; 15-well pipe; 16-clay; 17-filter material; 18-filter screen; 19-submersible pump; 20-outlet pipe. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. 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 work are within the scope of protection of the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0037] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0038] Example 1 This embodiment provides a construction method for a waterproof structure of a foundation pit dewatering well in a water-rich area. The waterproof structure of a foundation pit dewatering well in a water-rich area is as follows: Figure 1 As shown, the construction method comprises the following steps: Step 1: After the foundation pit is excavated to the bottom and the dewatering well completes the dewatering operation, backfill the dewatering well with sand and gravel in a mass ratio of 1:1 to a height of 1m below the ground, and then pour micro-expansive concrete to the bottom of the well pipe groove 14.

[0039] Step 2: After the bottom surface of the foundation pit is leveled, first lay the hydrophobic plate 7, and then insert the steel pipe 12 of the water-stop steel plate ring 1 into the well pipe groove 14. The outer periphery of the steel pipe 12 of the water-stop steel plate ring 1 is provided with 4 layers of serrated steel plate rings 13, and the bottom layer of steel plate ring 13 is stuck on the top surface of the hydrophobic plate 7, and the gap between the two is sealed with an expandable rubber waterstop strip 11.

[0040] Step 3: pour the cushion layer 8 and then construct the waterproof layer 9; the plane of the waterproof layer 9 is in close contact with the surface of the cushion layer 8, and the side of the waterproof layer 9 is turned up to the bottom of the steel plate ring 13 above the lowest steel plate ring 13.

[0041] Step 4: pour micro-expansive concrete in the steel pipe 12 of the water-stop steel plate ring 1 to a height of 0.2 m below the top surface of the steel pipe 12 ; pour the raft 10 so that the top surface of the raft 10 is flush with the top surface of the steel pipe 12 .

[0042] Step 5: Weld the first steel plate 4 to the inner wall of the steel pipe 12 to seal the slightly expansive concrete; fill the sealing material 6 on the top of the first steel plate 4, and the sealing material 6 is made of SQ404 and is water-tight; then weld the second steel plate 5 to the inner wall of the steel pipe 2 to seal the sealing material 6, so that the top surface of the second steel plate 5 is at the same height as the top surface of the raft 10, and the construction of the precipitation well waterproof structure is completed.

[0043] Example 2 This embodiment provides a waterproof structure for a water-rich area foundation pit dewatering well constructed based on the construction method provided in Example 1, such as Figure 1 shown.

[0044] The waterproof structure of the water-rich area foundation pit dewatering well includes: a water-stop steel plate ring 1, a sand and gravel layer 2, a slightly expansive concrete layer 3, a first steel plate 4, a second steel plate 5, a sealing material layer 6, a hydrophobic plate 7, a cushion layer 8, a waterproof layer 9, a raft plate 10 and an expansive rubber waterstop 11.

[0045] Among them, the water-stop steel plate ring 1 includes a steel pipe 12 and 4 layers of steel plate rings 13 distributed in a zigzag shape on the outer circumference of the steel pipe. The ring width of the steel plate ring is 15 cm, the spacing is 10 cm, and the spacing between the two bottom layers of steel plate rings is 20 cm; the bottom of the steel pipe 12 is inserted into the well pipe groove, and the well pipe groove is an annular recessed area opened on the inner wall of the top of the well pipe. The height of the well pipe groove is 15 cm, the inner diameter of the well pipe groove is 35 cm, and the outer diameter is 40 cm.

[0046] The internal space formed by the steel pipe 12 and the well pipe is composed of a sand and gravel layer 2 and a slightly expansive concrete layer 3 from bottom to top. A first steel plate 4 and a second steel plate 5 are provided on the top of the slightly expansive concrete layer 3. The edges of the first steel plate 4 and the second steel plate 5 are respectively fixedly connected to the inner wall of the steel pipe 12, and a sealing material layer 6 is provided between the two. The periphery of the waterstop steel plate ring 1 is provided with a hydrophobic plate 7, a cushion layer 8, a waterproof layer 9 and a raft plate 10 from bottom to top. The bottommost steel plate ring 13 of the waterstop steel plate ring is clamped on the top surface of the hydrophobic plate 7, and an expansive rubber waterstop strip 11 is provided in the external gap between the two.

[0047] Among them, the hydrophobic plate 7 is an arched sandwich plate made of plastic, the bottom of which is a hollow arch for drainage, and the upper part is dense and has the corresponding pressure-bearing capacity; the cushion layer 8 is a plain concrete layer, which is laid after the installation of the water-stop steel plate ring 1 and the expansion rubber water-stop belt is completed; the waterproof layer 9 is laid after the cushion layer 8 is completed and hardened, and the waterproof layer 9 adopts a SBS modified asphalt waterproof membrane with a thickness of 5 mm. The plane of the waterproof layer 9 is close to the cushion layer 8, and the side of the waterproof layer 9 is turned up to the bottom of the second steel plate ring 13; the raft 10 is made of reinforced concrete after the waterproof layer 9 is completed.

[0048] Furthermore, the micro-expansive concrete used in the micro-expansive concrete layer 3 has a quick-setting effect. The well pipe is filled to a height of 0.2m below the top surface of the raft slab. After being welded and sealed with a first steel plate 4, SQ404 is filled to prevent water leakage. The filling thickness is 20cm. Then, the second steel plate 5 is welded and sealed. The top surface height of the second steel plate 5 is consistent with the top surface of the raft slab 10.

[0049] In this embodiment, a sand and gravel layer 2 is arranged at the bottom of the well pipe, and a hydrophobic plate 7 is arranged outside the well pipe. The gaps in the sand and gravel and the hydrophobic space of the hydrophobic plate 7 can maintain the balance of groundwater pressure, and can slowly infiltrate and flow below the cushion layer 8, reducing the risk of leakage caused by breaking through the cushion layer due to the action of groundwater pressure; a multi-layer waterproof structure is adopted in the main structure construction stage to avoid the later leakage of the bottom plate caused by the abundant groundwater in the water-rich area breaking through the waterproof layer, effectively enhance the waterproof capacity of the precipitation well, and solve the problem of waterproofing of the precipitation well in the foundation pit in the water-rich area in the later stage.

[0050] Example 3 This embodiment provides a water-rich area foundation pit dewatering well waterproof structure and its construction method for use in a water-rich area foundation pit dewatering project, the dewatering well and the dewatering well waterproof structure are respectively as follows Figure 2 and Figure 1 As shown, the following steps are included: Step 1: Excavate the drainage wellhead: According to the site plane, site and geological conditions, arrange the location and depth of the drainage well according to actual needs and excavate the drainage wellhead to meet site needs.

[0051] Step 2: Install the sandless concrete well pipe: After the excavation of the drainage wellhead is completed, the well pipe 15 is lowered into the drainage wellhead and located in the middle of the wellhead. The well pipe 15 adopts a prefabricated sandless concrete well pipe, in which the filter screen 18 is prefabricated inside the well pipe 15 in advance, and the filter screen is set about 2m above the bottom of the well pipe 15.

[0052] Step 3: Filling filter material and clay: After the well pipe 15 is installed and temporarily fixed, start to symmetrically and evenly fill the filter material 17 on both sides until it is about 2m below the ground; then start to symmetrically and evenly fill the clay 16 on both sides until it is flush with the ground; the filter material 17 is permeable and can filter impurities in the groundwater.

[0053] Step 4: Install the submersible pump and outlet pipe: After filling the filter material 17 and clay 16, connect the outlet pipe 20 to the submersible pump 19, and then slowly lower the submersible pump 19 to the bottom of the filter screen 18. When the water level rises to the position of the water inlet of the submersible pump 19, it will start to work and pump water to a fixed drainage ditch or water collection well.

[0054] Step 5: Backfill with sand and gravel: After the foundation pit is excavated to the bottom and precipitation is completed, start to quickly backfill 1:1 sand and gravel to about 1m below the ground.

[0055] Step 6: pouring micro-expansion concrete: After the sand and gravel are filled in place, start pouring micro-expansion concrete to the height of the bottom surface of the well pipe groove 14, and at the same time level the bottom surface of the surrounding foundation pit for subsequent work.

[0056] Step 7: Install the drain plate: After the bottom surface of the foundation pit is leveled, start laying the drain plate 7. Each drain plate 7 should be spliced ​​tightly to form a good drainage system.

[0057] Step 8: Install the water-stop steel plate ring and the expansion rubber waterstop strip: After the installation of the hydrophobic plate 7 is completed, insert the steel pipe 12 of the water-stop steel plate ring 1 into the well pipe groove 14. The first steel plate ring 13 is just stuck on the top surface of the hydrophobic plate 7. After it is firmly installed, the first steel plate ring 13 on the side and the hydrophobic plate 7 and the external gap are sealed with the expansion rubber waterstop strip 11. There are multiple layers of steel plate rings 13 on the side to form a serrated shape, which can effectively extend the water seepage path.

[0058] Step 9: pouring cushion layer and constructing waterproof layer: after the expansion rubber waterstop 11 is installed, start pouring cushion layer 8; after the cushion layer 8 hardens, start constructing waterproof layer 9, with the plane close to the cushion surface and the side turned up to the bottom of the second steel plate ring 13 of the waterstop steel plate ring 1.

[0059] Step 10: Casting raft slab and micro-expansive concrete: After the construction of cushion layer 8 and waterproof layer 9 is completed, first cast the micro-expansive concrete in the waterstop steel plate ring 1, and cast the micro-expansive concrete to about 0.2m below the top surface of steel pipe 12, and then cast the raft slab 10, and the top surface of raft slab 10 is flush with the top surface of steel pipe 12 of waterstop steel plate ring 1.

[0060] Step 11: Install steel plate and fill with water to prevent leakage: After the micro-expansive concrete hardens, use the first steel plate 4 to weld and seal, then fill with water to prevent leakage on the first steel plate 4 to form the last waterproof line, and finally use the second steel plate 5 to weld and seal, and the top surface height of the second steel plate 5 is consistent with the top surface of the raft 10.

[0061] This embodiment innovatively integrates the construction of precipitation wells, precipitation construction and the later waterproofing structure of precipitation wells provided in Example 1 to form a complete construction method system; at the same time, it supplements and improves the waterproofing system provided in Example 2 on the basis of the traditional precipitation well waterproofing structure to form a good waterproofing effect.

[0062] This embodiment adopts an overall design to form a complete system from the construction and use of precipitation wells to the later sealing, and for the first time achieves a breakthrough in traditional construction efficiency and cost, avoiding the problem of later leakage due to poor sealing effect of precipitation wells; a multi-line waterproofing line design is adopted, and drainage measures are added, with a combination of dredging, guiding, drainage and prevention, the waterproofing effect is significant, the construction efficiency is improved, the cost is reduced, and it has broad prospects for promotion and application.

[0063] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for a waterproof structure of a foundation pit dewatering well in a water-rich area, characterized in that: The following steps are involved: S1. After the foundation pit is excavated to the bottom and the dewatering well has completed the dewatering operation, backfill the dewatering well with sand and gravel to a certain height below the ground, and then pour micro-expansion concrete to the bottom of the well pipe groove; S2. After the bottom surface of the foundation pit is leveled, a water-draining plate is laid first, and then the steel pipe with a water-stop steel plate ring is inserted into the well pipe clamping groove. The outer circumference of the steel pipe is provided with several layers of steel plate rings distributed in a zigzag shape, and the bottom layer of steel plate ring is clamped on the top surface of the water-draining plate, and the gap between the two is blocked by an expansion rubber water-stop strip; S3, pouring the cushion layer, and then constructing the waterproof layer; the plane of the waterproof layer is close to the surface of the cushion layer, and the side of the waterproof layer is turned up to the bottom of the steel plate ring above the lowest steel plate ring; S4. Pour micro-expansion concrete in the steel pipe of the water-stop steel plate ring to a certain distance below the top surface of the topmost steel plate ring; pour the raft slab so that the top surface of the raft slab is flush with the top surface of the steel pipe; S5. Weld the first steel plate to the inner wall of the steel pipe to seal the slightly expansive concrete; fill the sealing material above the first steel plate, and then weld the second steel plate to the inner wall of the steel pipe to seal the sealing material, thereby completing the construction of the precipitation well waterproof structure.

2. The construction method according to claim 1, characterized in that: In step S1, gravel is backfilled into the precipitation well to a height of 0.8-1.2 m below the ground, wherein the gravel is a mixture of sand and stone in a mass ratio of 1:

1.

3. The construction method according to claim 1, characterized in that: In step S1, the well pipe clamping groove is an annular recessed area opened on the inner wall of the top of the well pipe, the height of the well pipe clamping groove is 10-20 cm, the inner diameter of the well pipe clamping groove is 30-40 cm, and the outer diameter is 35-45 cm.

4. The construction method according to claim 1, characterized in that: In step S2, the number of water-stop steel plate rings is not less than 4 layers; the width of the steel plate ring is 12-18 cm, the spacing between the two steel plate rings in the bottom layer is 15-25 cm, and the spacing between the remaining steel plate rings is 8-12 cm.

5. The construction method according to claim 1, characterized in that: In step S3, the waterproof layer is made of SBS modified asphalt waterproof membrane with a thickness of 4-6 mm.

6. The construction method according to claim 1, characterized in that: In step S4, the distance between the top surface of the slightly expansive concrete in the water-stop steel plate ring and the top surface of the steel pipe is 0.15-0.25m.

7. The construction method according to claim 1, characterized in that: In step S5, the filling height of the plugging material is 15-20 cm; the plugging material is SQ404 which is watertight.

8. The construction method according to claim 1, characterized in that: In step S5, the height of the top surface of the second steel plate is kept consistent with the height of the top surface of the raft plate.

9. A waterproof structure for a foundation pit dewatering well in a water-rich area, characterized in that: It is constructed by the construction method according to any one of claims 1 to 8; The waterproof structure of the water-rich area foundation pit dewatering well includes: a water-stop steel plate ring, a sand and gravel layer, a slightly expansive concrete layer, a first steel plate, a second steel plate, a plugging material layer, a hydrophobic plate, a cushion layer, a waterproof layer, a raft plate and an expansive rubber waterstop; The water-stop steel plate ring comprises a steel pipe and a plurality of steel plate rings distributed in a zigzag shape on the outer circumference of the steel pipe; The bottom of the steel pipe is inserted into the well pipe slot, and the internal space formed by the steel pipe and the well pipe is a sandstone layer and a micro-expansive concrete layer from bottom to top. The top of the micro-expansive concrete layer is provided with a first steel plate and a second steel plate. The edges of the first steel plate and the second steel plate are respectively fixedly connected to the inner wall of the steel pipe, and a plugging material layer is provided between the two. The periphery of the water-stop steel plate ring is provided with a hydrophobic plate, a cushion layer, a waterproof layer and a raft plate in order from bottom to top; the lowest steel plate ring of the water-stop steel plate ring is clamped on the top surface of the hydrophobic plate, and an expansion rubber water-stop strip is provided in the external gap between the two.

10. Application of the waterproof structure of the foundation pit dewatering well in water-rich areas according to claim 9 in foundation pit dewatering projects in water-rich areas.

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