Sealing Structure and Method for Pressure Relief Wells in High-Head Foundation Pit
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CCCC FOURTH HARBOR ENG INST CO LTD
- Filing Date
- 2024-08-21
- Publication Date
- 2026-05-26
Smart Images
Figure CN118958347B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of decompression well construction technology, and in particular to the sealing structure and method for decompression wells in high-head foundation pits. Background Technology
[0002] As the excavation depth of the foundation pit increases, the thickness of the relatively impermeable layer at the bottom of the pit continuously decreases, and the head difference between the inside and outside of the pit gradually increases. Before the anti-buoyancy measures of the main structure are in place, structural buoyancy problems will be encountered. Currently, the measures adopted in engineering are basically to first install pressure relief wells inside and outside the foundation pit, and then extract groundwater during the excavation process to lower the water level, thereby ensuring the stability of the bottom of the foundation pit during the excavation process. After the relevant stability conditions meet the specifications, the pressure relief wells are then sealed.
[0003] In existing technologies, the groundwater level in coastal areas is shallow, with abundant and rapid recharge sources. If the excavation depth of the foundation pit is deep or after sealing some of the pressure relief wells, the pressure difference between the water head inside and outside the foundation pit during the sealing process is large. On the one hand, this causes groundwater to rush into the pressure relief wells very quickly during the sealing process, and the sealing material is washed away by the groundwater and cannot effectively seal and stop the water. On the other hand, if the soil around the well is not reinforced during the sealing process, it may be damaged by groundwater seepage. Summary of the Invention
[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a sealing structure and method for pressure relief wells in high-head foundation pits, which can effectively reduce the adverse effects of groundwater pressure gradually increasing on the sudden surge and damage to the soil around the well during the sealing process.
[0005] According to a first aspect of the present invention, a sealing structure for a high-head foundation pit decompression well includes a water-stopping structure disposed at the lower end of the structural base plate. The water-stopping structure includes a well casing and a water-stopping pad. The well casing is connected to the well wall of the decompression well. Multiple water-stopping wing rings and multiple shear-resistant components are disposed on the outer wall of the well casing. The multiple water-stopping wing rings and multiple shear-resistant components are spaced apart axially. The water-stopping pad is coaxially disposed with the well casing and passes through the well casing. The water-stopping pad is located at the end of the well casing near the structural base plate. An anti-surge structure is also included. At the lower end of the base plate, the anti-surge structure is located in a relatively impermeable soil layer. The anti-surge structure includes an anti-surge block, which is coaxially arranged with the well casing and is wrapped around the outer wall of the well casing. All water-stop wing rings and all shear components are located inside the anti-surge block. The anti-surge block is used to block the sudden surge of groundwater pressure into the soil layer around the water-reducing well. The sealing structure is set in the water-reducing well and extends from the water-reducing well into the interior of the well casing. The sealing structure is used to prevent groundwater from flowing into the water-stop structure along the water-reducing well.
[0006] The sealing structure of the high-head foundation pit decompression well according to the present invention has at least the following beneficial effects: the water-stopping structure and the anti-surge structure are set at the lower end of the structural base plate, and the anti-surge block counteracts the groundwater pressure, preventing groundwater from seeping into the well casing. At the same time, sealing the decompression well can, on the one hand, avoid the adverse effects of sudden surge damage to the soil layer around the decompression well after the groundwater pressure gradually increases, prevent soil seepage deformation to enhance the stability of the foundation, and on the other hand, cut off the pollution path and effectively reduce the impact of groundwater seepage on the main structural base plate after the well wall is corroded in the later stage.
[0007] According to some embodiments of the present invention, a reducing member is provided at the lower end of the well casing, the well casing is connected to the water reduction well through the reducing member, the reducing member is inserted in the water reduction well, and the inner diameter of the reducing member gradually decreases in the direction close to the water reduction well.
[0008] According to some embodiments of the present invention, a waterproof coating layer is provided on the outer wall of the well casing.
[0009] According to some embodiments of the present invention, the shear-resistant component includes a plurality of shear-resistant steel bars evenly distributed in a ring. Each shear-resistant steel bar has a connector and an anchor at its opposite ends. The connector is perpendicular to the shear-resistant steel bar and parallel to the well casing. The shear-resistant steel bar is connected to the side wall of the well casing through the connector and is anchored in the anti-surge block through the anchor.
[0010] According to some embodiments of the present invention, the anti-surge structure further includes a first cushion layer disposed at the lower end of the anti-surge block.
[0011] According to some embodiments of the present invention, the size of the anti-surge block is larger than the size of the pre-reserved pit in the structural base plate.
[0012] According to a second aspect of the present invention, a method for sealing a high-head foundation pit decompression well, employing the aforementioned sealing structure for the high-head foundation pit decompression well, includes:
[0013] S1: Maintain depressurization operations within the depressurization well, excavate an anti-surge block pit near the depressurization well, and cut off the depressurization well at a position higher than the bottom of the anti-surge block pit;
[0014] S2: Maintain depressurization operations inside the depressurization well and fix the well casing to the upper end of the depressurization well;
[0015] S3: Lay the first cushion layer at the bottom of the anti-surge block foundation pit. After the first cushion layer reaches the design strength, build a concrete formwork and pour concrete into the concrete formwork to form the anti-surge block.
[0016] S4: After the anti-surge block reaches the design strength, backfill and compact the area around the anti-surge block, construct the structural base plate on the top of the anti-surge block, and reserve the pit corresponding to the pressure relief well on the structural base plate.
[0017] S5: Stop the decompression operation of the decompression well, pump out the overflowing water from the decompression well in the pit, and fill the decompression well with concrete until the water level at the wellhead no longer rises.
[0018] S6: Place the water-stop pad inside the well casing, construct the filling base plate in the pit, and make the filling base plate flush with the top of the structural base plate.
[0019] According to some embodiments of the present invention, in S4, a waterstop is provided circumferentially on the inner wall of the pit, the waterstop extending from the inside of the structural base plate toward the inside of the pit, and the waterstop is used for structural water stopping.
[0020] According to some embodiments of the present invention, in S5, a waterproof membrane is laid in the well casing, and the waterproof membrane extends from the inside of the well casing to the pit.
[0021] According to some embodiments of the present invention, in S6, the compressive strength of the filling base plate is greater than the compressive strength of the structural base plate.
[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0024] Figure 1 This is a schematic diagram of the sealing structure of a high-head foundation pit decompression well according to the first aspect of the present invention;
[0025] Figure 2 yes Figure 1 A schematic diagram of the water-stopping structure;
[0026] Figure 3 yes Figure 2 Top view in the middle;
[0027] Figure 4 This is a schematic diagram of construction S1 in the sealing method of the high-head foundation pit pressure relief well according to the second aspect of the present invention;
[0028] Figure 5 This is a schematic diagram of construction S2 in the sealing method of the high-head foundation pit pressure relief well according to the second aspect of the present invention;
[0029] Figure 6 This is a schematic diagram of construction steps S3 and S4 in the sealing method for a high-head foundation pit pressure relief well according to the second aspect of the present invention;
[0030] Figure 7 This is a schematic diagram of construction step S5 in the sealing method for a high-head foundation pit pressure relief well according to the second aspect of the present invention;
[0031] Figure 8 This is a schematic flowchart of a method for sealing a high-head foundation pit decompression well according to a second aspect embodiment of the present invention.
[0032] Figure label:
[0033] Water-stopping structure 100, well sleeve 110, water-stopping wing ring 111, shear-resistant component 112, shear-resistant steel bar 1121, connector 1122, anchor 1123, diameter reduction component 113, water-stopping pad 120, flange ring 121, flange 122.
[0034] Anti-surge structure 200, anti-surge block 210, first cushion layer 220;
[0035] 300mm sealing structure;
[0036] Structural base plate 400, fill base plate 410, second cushion layer 420, fill cushion layer 421;
[0037] Impermeable soil layer 10, water reduction well 20, water pump 30, anti-surge foundation pit 40, pit 50, waterstop 51. Detailed Implementation
[0038] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.
[0039] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0040] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0041] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.
[0042] refer to Figures 1 to 8 The sealing structure of a high-head foundation pit decompression well according to an embodiment of the present invention is described.
[0043] like Figures 1 to 8 As shown, the sealing structure of the high-head foundation pit pressure relief well according to the first aspect of the present invention includes a water-stopping structure 100, which is disposed at the lower end of the structural base plate 400. The water-stopping structure 100 includes a well sleeve 110 and a water-stopping pad 120. The well sleeve 110 is connected to the well wall of the pressure relief well. A plurality of water-stopping wing rings 111 and a plurality of shear-resistant components 112 are provided on the outer wall of the well sleeve 110. The plurality of water-stopping wing rings 111 and the plurality of shear-resistant components 112 are spaced apart along the axial direction. The water-stopping pad 120 is coaxially disposed with the well sleeve 110 and passes through the well sleeve 110. The water-stopping pad 120 is located at the end of the well sleeve 110 near the structural base plate 400. An anti-surge structure 200 is also included. The anti-surge structure 200 is located at the lower end of the structural base plate 400 and is situated in the relatively impermeable soil layer 10. The anti-surge structure 200 includes an anti-surge block 210, which is coaxially arranged with the well casing 110. The anti-surge block 210 is wrapped around the outer wall of the well casing 110. All the water-stopping rings 111 and all the shear-resistant components 112 are located inside the anti-surge block 210. The anti-surge block 210 is used to block the sudden surge of groundwater pressure into the soil layer around the water-reducing well 20. The sealing structure 300 is located in the water-reducing well 20 and spans between the well casing 110 and the water-reducing well 20. The sealing structure 300 is used to prevent groundwater from flowing into the water-stopping structure 100 along the water-reducing well 20.
[0044] The geographical advantages of coastal areas make coastal land a scarce resource, leading to a surge in high-rise buildings to improve land utilization efficiency. It should be noted that while coastal areas have ample groundwater supply from nearby seawater, their groundwater levels are shallow and fluctuate with the tides. However, as the excavation depth of the foundation pit increases, the thickness of the relatively impermeable layer at the bottom of the pit decreases, and the head difference between the inside and outside of the pit gradually increases. This results in a safety factor for the stability of the pit bottom during sudden inrushes falling below 1.0. Before the main structure's anti-buoyancy measures are implemented, structural buoyancy issues will arise.
[0045] For the sealing of pressure relief wells in high-head foundation pits in coastal areas, several problems typically arise during the sealing construction process. Firstly, because groundwater in coastal areas is connected to seawater, and groundwater is corrosive to building materials, the well walls are prone to corrosion and damage under the long-term influence of groundwater. Groundwater seeps upwards along the well walls left in the foundation slab structure, corroding the reinforcing steel of the main structural slab and affecting its material properties. Secondly, the groundwater level in coastal areas is shallow, with ample and rapid recharge. If the foundation pit is deep, or after sealing some pressure relief wells, the pressure difference between the inside and outside of the pit is significant. During the sealing process, groundwater will rush into the pressure relief wells at a high speed, causing the sealing material to be washed away and unable to effectively stop the water flow. If the soil around the pressure relief well is not reinforced during sealing, it may even be damaged by groundwater seepage.
[0046] like Figure 1 and Figure 2 As shown, the water-stopping structure 100 and the anti-surge structure 200 are embedded at the lower end of the structural base plate 400. The well sleeve 110 is axially positioned above the pressure-reducing well 20, and its diameter and thickness are the same as the pressure-reducing well. The anti-surge block 210 is wrapped around the outer walls of the well sleeve 110 and the pressure-reducing well 20, covering the connection between them. Two water-stopping wing rings 111 and two shear-resistant components 112 are axially spaced on the outer peripheral wall of the well sleeve 110. Each shear-resistant component 112 includes at least eight evenly distributed shear-resistant steel bars 1121 arranged in a ring. All the water-stopping wing rings 111 and shear-resistant steel bars 1121 are located within the anti-surge block 210. A water-stopping pad 120 is installed near the upper end of the well casing 110. A sealing structure 300 is installed in the water-reducing well 20, and the sealing structure 300 extends upward into the interior of the well casing 110, thus forming a multi-layered barrier structure in combination with the sealing structure 300 and the anti-surge block 210. Therefore, by placing the water-stopping structure 100 and the anti-surge structure 200 at the lower end of the structural base slab 400, and using the anti-surge block 210 to counteract groundwater pressure, groundwater seepage into the well casing 110 is prevented. Simultaneously, the pressure-reducing well is sealed. This avoids the adverse effects of sudden surges in the soil around the water-reducing well 20 caused by gradually increasing groundwater pressure, preventing soil seepage deformation and enhancing foundation stability. Furthermore, it cuts off pollution pathways, effectively reducing the impact of groundwater seepage after subsequent corrosion of the well wall on the main structural base slab 400.
[0047] Specifically, the water-stop gasket 120 is fixedly installed in the well sleeve 110 via a flange. The flange includes a flange ring 121, a flange plate 122, and bolts. The flange ring 121, water-stop gasket 120, and flange plate 122 all have bolt holes of the same size and number, and are connected by bolts. Further, the diameter of the flange plate 122 is the same as the outer diameter of the flange ring 121, the diameter of the water-stop gasket 120 is the same as the outer diameter of the flange ring 121, the thickness of the flange ring 121 is not less than 20mm, the thickness of the flange plate 122 should be 5mm to 10mm, and the water-stop gasket 120 is made of polyvinyl chloride rubber and plastic with a thickness of 1mm to 2mm.
[0048] Specifically, the well casing 110 is made of stainless steel, and a waterproof coating layer is provided on the outer wall of the well casing 110. The diameter of the well casing 110 is greater than 300mm.
[0049] Specifically, the water-stopping wing ring 111 is annularly sleeved on the well sleeve 110, and the water-stopping wing ring 111 is made of steel.
[0050] Specifically, the anti-surge block 210 has a square shape when viewed from top to bottom, but its shape is a cube. The anti-surge block 210 is made of underwater impermeable concrete, and its grade is the same as that of the concrete of the structural base plate 400. That is, the compressive strength of the anti-surge block 210 is the same as that of the structural base plate 400.
[0051] Specifically, the anti-surge block 210 is flush with the upper part of the well casing 110, and the structural base plate 400 is covered and installed on the anti-surge block 210 and the well casing 110.
[0052] It should be noted that, to facilitate the insertion of the well casing 110 into the pressure relief well, in actual construction, a well casing 110 with a diameter smaller than that of the pressure relief well is usually used. Then, the space between the well casing 110 and the pressure relief well is filled and sealed using methods such as hemp fiber and oil paste. However, this method carries the risk of incomplete sealing. Figure 1 As shown, in some specific embodiments of the present invention, a reducing member 113 is provided at the lower end of the well casing 110. The well casing 110 is connected to the water reduction well 20 through the reducing member 113. The reducing member 113 is inserted into the water reduction well 20. The inner diameter of the reducing member 113 gradually decreases in the direction close to the water reduction well 20. By reducing the diameter, the stability and structural strength of the connection between the well casing 110 and the water reduction well 20 can be increased. At the same time, the sealing of the connection part can be effectively improved, reducing the possibility of groundwater inrush.
[0053] In some specific embodiments of the present invention, the shear-resistant component 112 includes a plurality of shear-resistant steel bars 1121 evenly distributed in a ring shape. Each shear-resistant steel bar 1121 has a connector 1122 and an anchor 1123 at its opposite ends. The connector 1122 is perpendicular to the shear-resistant steel bar 1121 and parallel to the well casing 110. The shear-resistant steel bars 1121 are connected to the sidewall of the well casing 110 through the connector 1122, and the shear-resistant steel bars 1121 are anchored in the anti-surge block 210 through the anchor 1123. Figure 3 As shown, the shear reinforcement bars 1121 of a single shear-resistant component 112 are all arranged circumferentially on the outer wall of the well casing 110. In this specific embodiment, eight shear reinforcement bars 1121 are provided. The eight shear reinforcement bars 1121 are arranged in a planar ring and one end connected to the well casing 110 points to the center of the well casing 110. The shear reinforcement bars 1121 are bent 90° and welded to the well casing 110 by a full weld through the connector 1122, and are anchored into the anti-surge block 210 by the anchor 1123 bent 180°. Furthermore, the type of shear reinforcement bars 1121 is consistent with the main structure.
[0054] In some specific embodiments of the present invention, the anti-surge structure 200 further includes a first cushion layer 220, which is disposed at the lower end of the anti-surge block 210. The first cushion layer 220 can fill and balance the surface unevenness between the structural base plate 400 and the foundation, disperse the load transmitted from the structural base plate 400 to the foundation, reduce local stress concentration, and help protect the structural base plate 400 and the foundation, thereby ensuring that the structural base plate 400 is placed on a stable foundation, thus improving the stability and safety of the structure and ensuring a firm and reliable connection between the structural base plate 400 and the foundation.
[0055] like Figures 1 to 4 As shown, the method for plugging a high-head foundation pit decompression well according to a second aspect embodiment of the present invention includes...
[0056] S1: Maintain depressurization operations within the depressurization well, excavate the anti-surge block 210 foundation pit near the depressurization well, and cut off the depressurization well at a position higher than the bottom of the anti-surge block 210 foundation pit;
[0057] S2: Maintain pressure reduction operations inside the pressure relief well, and fix the well casing 110 to the upper end of the pressure relief well;
[0058] S3: Lay the first cushion layer 220 at the bottom of the pit of the anti-surge block 210. After the first cushion layer 220 reaches the design strength, build a concrete formwork and pour concrete in the concrete formwork to form the anti-surge block 210.
[0059] S4: After the anti-surge block 210 reaches the design strength, backfill and compact the area around the anti-surge block 210, construct the structural base plate 400 at the top of the anti-surge block 210, and reserve the pit 50 corresponding to the pressure relief well on the structural base plate 400.
[0060] S5: Stop the decompression operation of the decompression well, pump out the water overflowing from the decompression well 20 in the pit 50, and fill the decompression well 20 with concrete until the water level at the wellhead of the decompression well 20 no longer rises.
[0061] S6: Place the water-stop pad 120 inside the well sleeve 110, construct the filling base plate 410 in the pit 50, and make the filling base plate 410 flush with the top of the structural base plate 400.
[0062] In S4, a waterstop 51 is provided circumferentially on the inner wall of the pit 50. The waterstop 51 extends from the inside of the structural base plate 400 toward the inside of the pit 50 and is used for structural water stop.
[0063] In some specific embodiments of the present invention, in S5, a waterproof membrane is laid in the well casing 110, and the waterproof membrane extends from the inside of the well casing 110 to the pit 50.
[0064] In some specific embodiments of the present invention, in S6, the compressive strength of the filling base plate 410 is greater than the compressive strength of the structural base plate 400.
[0065] The following specific embodiment illustrates the sealing method for the pressure relief well in this high-head foundation pit.
[0066] S1: As Figure 4 As shown, the water pump 30 in the pressure relief well is kept in pressure reduction operation. The water pump 30 is connected to the water pipe to pump the groundwater out of the foundation pit, so as to ensure the anti-surge stability of the relatively impermeable soil layer 10 at the bottom of the foundation pit and meet the requirements of dry operation at the bottom of the pit.
[0067] Excavate the foundation pit to the bottom elevation of the designed pit, measure and locate the anti-surge block 210 near the pressure relief well and mark the plane dimensions of the anti-surge block 210 at the bottom of the pit, and adopt the construction method of slope excavation according to the preset excavation boundary, and use an excavator to excavate down to the bottom of the anti-surge pit.
[0068] S2: As Figure 5 As shown, the pump 30 in the pressure relief well maintains pressure relief operation. The pressure relief well is cut off at a position 300mm above the bottom of the anti-surge pit. A sand mill is used to repair and level the cut-off position of the pressure relief well and to grind the inner and outer walls within 50mm below the wellhead of the pressure relief well smooth in order to be welded to the well casing 110.
[0069] Support the water pipe of the water pump 30 to prevent the weight of the water pipe from supporting the well casing 110. Then, pass the water pipe of the water pump 30 through the prefabricated well casing 110 so that the well casing 110 and the pressure relief well are connected and kept vertical. Weld the well casing 110 and the pressure relief well by full welding at the joint.
[0070] S3: As Figure 6 As shown, after the weld has cooled naturally, a first cushion layer 220 is laid at the bottom of the pit of the anti-surge block 210 foundation pit. After the first cushion layer 220 has reached the design strength, the concrete formwork is erected according to the preset size. Water-resistant concrete of the same type as the structural base plate 400 is poured in the concrete formwork, and the pouring height of the concrete is level with the wellhead height of the well casing 110, located at the bottom of the foundation pit.
[0071] S4: As Figure 6 As shown, after the concrete of the anti-surge block 210 reaches the predetermined strength, the second cushion layer 420 of the structural base plate 400 is laid according to the drawings, the steel bars are tied, the concrete formwork is erected, and the concrete is poured. A cubic reserved pit 50 with a plane size of 1m×1m and a thickness of the same as that of the structural base plate 400 is reserved at the location corresponding to the pressure relief well.
[0072] It should be noted that the reserved reinforcing bars in the structural base slab 400 must protrude from the concrete surface, with a reserved length of 50mm. They are welded to the subsequent reinforcing bars of the pit 50. A steel plate waterstop 51 is installed around the middle of the pit 50, with a width of 200mm. 100mm of the steel plate waterstop 51 is poured into the concrete of the structural base slab 400, and the other 100mm is poured into the concrete of the reserved pit 50 for structural waterstopping.
[0073] S5: As Figure 7 As shown, after the structural base plate 400 meets the anti-buoyancy requirements, a water pump 30 is placed in the reserved pit 50 of the structural base plate 400, the water pump 30 of the pressure relief well is turned off to stop pumping water, and the water pump 30 of the pressure relief well is slowly pulled out of the pressure relief well for recovery.
[0074] It should be noted that when the pump 30 of the groundwater pressure relief well stops pumping, groundwater will gush out from the wellhead of the well casing 110 into the reserved pit 50 of the structural base slab 400. The water pump 30 in the reserved pit 50 is connected to an external water pipe to pump the gushing water into the permanent water collection well set in the structural base slab 400. The water pump 30 in the water collection well will concentrate and pump the groundwater out of the foundation pit.
[0075] Maintain the pumping operation of pump 30 in pit 50, insert a 200mm diameter guide pipe into the pressure relief well, fix the upper end to the on-site support with a steel wire rope, and the lower end is about 0.5m away from the bottom of the pressure relief well;
[0076] Furthermore, a graduated measuring rope is lowered along with the guide pipe. During the pouring process, it is manually lifted along with the underwater self-compacting concrete pouring surface to determine the depth to which the guide pipe is embedded in the self-compacting concrete. The minimum required depth for the guide pipe to be embedded in the underwater self-compacting concrete is 1.1m to 1.5m to ensure that the underwater self-compacting concrete flows upward from the bottom, while preventing the underwater self-compacting concrete being poured from being washed away by groundwater. Of course, to avoid the guide pipe being unable to be pulled out of the underwater self-compacting concrete in the end, the depth of the guide pipe embedded in the underwater self-compacting concrete shall not exceed 6m.
[0077] The underwater self-compacting concrete is poured into the decompression well along the guide pipe. During the pouring process, the amount of water flowing into the wellhead and the water level change must be monitored at all times. At the same time, the scale of the measuring rope should be monitored to determine the burial depth of the guide pipe. When the guide pipe is buried 3m into the self-compacting concrete, the guide pipe is lifted upward to ensure its minimum burial depth.
[0078] When the groundwater flow at the wellhead continues to decrease and the water level at the wellhead stops rising after pumping is stopped, stop the underwater self-compacting concrete pouring, pull the guide pipe out of the decompression well, turn off the pumping pump 30 and pull it out of the pit 50.
[0079] S6: The water-stop gasket 120, flange 122 and flange ring 121 are tightly connected with bolts. The water-stop flange gasket is located between flange 122 and flange ring 121 to ensure the water-stopping effect.
[0080] Clean the inner wall of the part above the flange 122 of the well sleeve 110. Lay waterproof membrane inside the well sleeve 110 and at the bottom of the pit 50. The waterproof membrane extends vertically upward along the wall of the well sleeve 110 into the pit 50. The waterproof membrane in the pit 50 covers the bottom of the pit and extends vertically upward 100mm along the wall of the pit 50.
[0081] It should be noted that a filling pad 421 is also provided at the bottom of the filling base slab 410. The filling pad 421 is used to fill the reserved pit 50 of the second pad 420, and the filling base slab 410 is used to fill the reserved pit 50 of the structural base slab 400. Specifically, micro-expansion concrete of a grade higher than that of the structural base slab 400 concrete is poured onto the waterproof membrane, and the pouring height of the concrete is flush with the bottom of the structural base slab 400 to form the filling pad 421 structure. The post-connected steel bars of the same type as those of the structural base slab 400 are connected and tied to the reserved steel bars by welding. The pit 50 is poured with micro-expansion concrete of a grade higher than that of the structural base slab 400 concrete, and the pouring height of the concrete is flush with the top of the structural base slab 400 to form the filling base slab 410 structure.
[0082] It should be noted that the joints of different waterproof membranes should be sealed with sealant to form a whole structure to ensure the waterproof membrane's water-stopping effect.
[0083] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A sealing structure for a high-head foundation pit decompression well, characterized in that, include: A water-stopping structure (100) is provided at the lower end of the structural base plate (400). The water-stopping structure (100) includes a well sleeve (110) and a water-stopping pad (120). The well sleeve (110) is connected to the well wall of the pressure relief well. Multiple water-stopping wing rings (111) and multiple shear-resistant components (112) are provided on the outer wall of the well sleeve (110). The multiple water-stopping wing rings (111) and multiple shear-resistant components (112) are spaced apart along the axial direction. The water-stopping pad (120) is coaxially arranged with the well sleeve (110). The water-stopping pad (120) passes through the well sleeve (110). The water-stopping pad (120) is located at one end of the well sleeve (110) near the structural base plate (400). An anti-surge structure (200) is provided at the lower end of the structural base plate (400). The anti-surge structure (200) is located in a relatively impermeable soil layer (10). The anti-surge structure (200) includes an anti-surge block (210). The anti-surge block (210) is coaxially arranged with the well casing (110). The anti-surge block (210) is wrapped around the outer wall of the well casing (110). All the water-stopping wing rings (111) and all the shear-resistant components (112) are located inside the anti-surge block (210). The anti-surge block (210) is used to block the sudden surge of groundwater pressure into the soil layer around the water-reducing well (20) after the groundwater pressure gradually increases. A sealing structure (300) is disposed in a water reduction well (20) and extends from the water reduction well (20) into the interior of the well casing (110). The sealing structure (300) is used to prevent groundwater from flowing into the water-stopping structure (100) along the water reduction well (20). The shear-resistant component (112) includes a plurality of shear-resistant steel bars (1121) evenly distributed in a ring. Each shear-resistant steel bar (1121) has a connector (1122) and an anchor (1123) respectively provided at its opposite ends. The connector (1122) is perpendicular to the shear-resistant steel bar (1121) and parallel to the well casing (110). The shear-resistant steel bar (1121) is connected to the side wall of the well casing (110) through the connector (1122) and the shear-resistant steel bar (1121) is anchored in the anti-surge block (210) through the anchor (1123). The size of the anti-surge block (210) is larger than the size of the reserved pit in the structural base plate (400).
2. The sealing structure for the high-head foundation pit decompression well according to claim 1, characterized in that, The lower end of the well casing (110) is provided with a reducing member (113). The well casing (110) is connected to the water reduction well (20) through the reducing member (113). The reducing member (113) is inserted in the water reduction well (20). The inner diameter of the reducing member (113) gradually decreases in the direction close to the water reduction well (20).
3. The sealing structure for the high-head foundation pit decompression well according to claim 1, characterized in that, The outer wall of the well casing (110) is provided with a waterproof coating layer.
4. The sealing structure for the high-head foundation pit decompression well according to claim 1, characterized in that, The anti-surge structure (200) further includes a first cushion layer (220), which is disposed at the lower end of the anti-surge block (210).
5. A method for sealing a high-head foundation pit decompression well, employing the sealing structure for a high-head foundation pit decompression well as described in any one of claims 1 to 4, characterized in that, include: S1: Maintain depressurization operation in the depressurization well, excavate the foundation pit of the anti-surge block (210) near the depressurization well, and cut off the depressurization well at a position higher than the bottom of the foundation pit of the anti-surge block (210); S2: Maintain pressure reduction operation inside the pressure relief well and fix the well casing (110) to the upper end of the pressure relief well; S3: Lay a first cushion layer (220) at the bottom of the pit of the anti-surge block (210). After the first cushion layer (220) reaches the design strength, build a concrete formwork and pour concrete in the concrete formwork to form the anti-surge block (210). S4: After the anti-surge block (210) reaches the design strength, the area around the anti-surge block (210) is backfilled and compacted. A structural base plate (400) is constructed at the upper end of the anti-surge block (210), and a pit (50) corresponding to the pressure relief well is reserved on the structural base plate (400). S5: Stop the decompression operation of the decompression well, pump out the overflowing water from the decompression well (20) in the pit (50), and fill the decompression well (20) with concrete until the water level at the wellhead of the decompression well (20) no longer rises. S6: Place the water-stop pad (120) inside the well sleeve (110), construct the filling base plate (410) in the pit (50), and make the filling base plate (410) flush with the top of the structural base plate (400).
6. The method for sealing high-head foundation pit decompression wells according to claim 5, characterized in that, In S4, a waterstop (51) is provided on the inner wall of the pit (50) along the circumferential direction. The waterstop (51) extends from the inside of the structural base plate (400) toward the inside of the pit (50) and is used for structural water stop.
7. The method for sealing high-head foundation pit pressure relief wells according to claim 5, characterized in that, In S5, a waterproof membrane is laid in the well casing (110), and the waterproof membrane extends from the inside of the well casing (110) to the pit (50).
8. The method for sealing high-head foundation pit pressure relief wells according to claim 5, characterized in that, In S6, the compressive strength of the filling base plate (410) is greater than the compressive strength of the structural base plate (400).