Structure for stabilizing water pressure around underground engineering and reducing leakage and construction method thereof

Abstract

The invention relates to a structure for stabilizing water pressure around underground engineering and reducing leakage and a construction method thereof. The structure comprises a foundation pit, an underground diaphragm wall framed around the foundation pit, a base arranged in the foundation pit and formed by pouring pervious concrete, and a structure body fixedly connected to the upper portion of the base. A plurality of drainage channels are arranged in the soil layer structure on the outer side of each underground diaphragm wall, the drainage channels are communicated with drainage ditches formed in the ground surface through inserting and beating openings, and the inserting and beating openings, the drainage ditches and the drainage channels form a pressure stabilizing drainage layer; a pressure-bearing water-resisting layer is arranged on the periphery of the structure body and comprises a horizontal annular channel arranged on the periphery of the structure body in a framing mode and a U-shaped channel wrapping the periphery and the bottom of the structure body, and the horizontal annular channel and the U-shaped channel are connected and communicated with each other. The U-shaped channel is arranged above the base, and the output end of the U-shaped channel is communicated with the drainage ditch; the horizontal annular channel and the U-shaped channel are fixedly connected to the inner side of the underground diaphragm wall; the structure of the soil layer around the structure main body can be kept stable, the leakage problem of the structure main body is prevented, when the structure main body is subjected to pressure, the pressure can be dispersed and consumed, the stress balance around the structure main body is kept, and leakage points are reduced.

Description

Technical Field

[0001] The present invention relates to a structure for stabilizing the water pressure around an underground project and reducing leakage and its construction method, belonging to the technical field of underground project drainage, pressure relief, anti-floating and anti-settlement. Background Art

[0002] To meet various demands of economic development, the construction of underground facilities such as subways and basements is a common practice. The construction of these underground facilities needs to go deep into the ground surface, and has large construction specifications and a long construction period, so it will have various impacts on the surrounding environment.

[0003] For example, the construction of a subway station will cause the following problems in the surrounding environment: First, the construction causes disturbance and deformation of the soil layer, resulting in ground settlement and deformation, and then problems such as damage to the original underground pipelines and facilities, and affecting the stability of surrounding buildings and underground facilities. Even after the subway station is completed and put into use, under the influence of ground settlement, friction occurs between the diaphragm wall and the side wall of the subway station, which will cause damage to the waterproof layer of the side wall and weaken its waterproof effect. Second, the construction will change the trajectory of underground water flow. Groundwater gathers around the subway station to form a high-pressure underground environment. The water pressure and osmotic pressure around the subway station continue to increase. Confined water will look for a breakthrough in the subway station, resulting in water leakage in the subway station. At the same time, the increased water pressure and osmotic pressure will cause the overall or partial destructive floating of the underground structure and adjacent structures. For the station track designed to meet specific requirements, due to the increased earth pressure and water pressure on its single layer, it is impossible to resist and make up for the deficiency in shear resistance of the wall columns by increasing the thickness of the outer wall and the diameter and quantity of steel bars, resulting in quality risks.

[0004] Chinese Patent with publication number CN112195980A discloses a water isolation, pressure control and anti-floating structure and its construction method. The anti-floating structure consists of a water isolation system, a surface drainage system and a pressure release system; the water isolation system refers to a cut-off wall that blocks the runoff path of groundwater, the surface drainage system is a drainage facility that intercepts, collects and discharges surface water, and the pressure release system consists of a permeable structure, a water collection structure, a water outlet structure and a monitoring and control module; it takes measures to block the lateral runoff recharge of groundwater, block the infiltration of surface water and release the basal water pressure, mainly through the "drainage" method to prevent leakage problems of the main structure and solve the anti-floating phenomenon of underground structures, but there is still a situation where groundwater breaks through the cut-off wall and exerts pressure on the main structure, resulting in leakage. Summary of the Invention

[0005] In order to overcome the above problems, the present invention provides a structure for stabilizing the water pressure around an underground project and reducing leakage, as well as a construction method thereof, which can maintain the stability of the soil layer structure around the main structure, prevent leakage problems from occurring in the main structure, and enable the pressure to be dispersed and consumed when the main structure is under pressure, keep the stress balance around the main structure, and reduce leakage points.

[0006] The technical solution of the present invention is as follows: A structure for stabilizing the water pressure around an underground project and reducing leakage includes a foundation pit, a diaphragm wall framed around the foundation pit, a base formed by pouring permeable concrete in the foundation pit, and a main structure fixedly connected above the base; several drainage channels are provided in the soil layer structure on the outer side of each diaphragm wall, and the drainage channels are connected to a drainage ditch arranged on the ground surface through insertion openings, and the insertion openings, the drainage ditch and several drainage channels form a pressure-stabilizing drainage layer; a pressure-bearing water-proof layer is provided on the outer periphery of the main structure, and the pressure-bearing water-proof layer includes a horizontal annular channel framed around the main structure, a U-shaped channel wrapping around the periphery and bottom of the main structure, and the horizontal annular channel and the U-shaped channel are connected and communicated with each other; the U-shaped channel is placed above the base, and the output end of the U-shaped channel is connected to the drainage ditch; the horizontal annular channel and the U-shaped channel are both fixedly connected to the inner side of the diaphragm wall.

[0007] Further, several rows of the insertion openings are arranged to extend away from the foundation pit on the ground surface of the outer periphery of each diaphragm wall, and several rows of insertion openings are connected through the drainage ditch, and the drainage ditch is connected to a three-stage sedimentation tank; the sum of the spacings of several rows of the insertion openings ≥ the depth of the foundation pit, and the adjacent two rows of insertion openings are arranged staggeredly; several drainage channels are provided in each insertion opening, and several drainage channels extend radially into the soil layer structure with it as the center point, and the drainage channels are off-site drainage boards, and the number of off-site drainage boards in each insertion opening ≤ 10; the bottom spacing of adjacent off-site drainage boards ≤ 2m.

[0008] Further, the U-shaped channel includes several bottom drainage boards fixedly connected to the top of the base and arranged in a horizontal and vertical cross pattern, and two ends of each bottom drainage board are respectively provided with vertical drainage boards perpendicular to and communicated with it; each vertical drainage board is laid along the height direction of the adjacent diaphragm wall, and the upper part of each vertical drainage board is connected to the drainage ditch interface in the adjacent insertion opening; the horizontal annular channel includes several transverse drainage boards arranged at intervals along the height direction of the inner side of each diaphragm wall, and the transverse drainage boards on the same horizontal plane on each diaphragm wall are connected end to end and communicated; the vertical drainage boards and the transverse drainage boards are both placed in the foundation pit.

[0009] Furthermore, surface reserved sections are provided at the upper parts of the off-site drainage boards and the vertical drainage boards. The surface reserved sections are placed in adjacent jacking openings, and the length of the surface reserved sections ≥ 1 m; the surface reserved sections of the off-site drainage boards and the vertical drainage boards are respectively folded in half and a rubber cap is sleeved on their outer circumferences, and a fastener is sleeved on the lower part of the rubber cap.

[0010] Furthermore, steel-plastic composite tension belts for increasing their strength are laid inside the off-site drainage boards and the vertical drainage boards.

[0011] Furthermore, the pressure-bearing water-resistant layer further includes a waterproof layer provided on the side of the horizontal annular channel and the U-shaped channel away from the diaphragm wall, and a geotextile layer provided on the other side of the waterproof layer; a structural body fixedly connected thereto is provided on the other side of the geotextile layer.

[0012] Furthermore, the off-site drainage boards, the vertical drainage boards, the horizontal drainage boards, and the bottom plate drainage boards are all solid-base plastic drainage boards with filter membranes for soft foundation treatment; the plastic drainage boards arranged crosswise are all connected and communicated through a sealed box.

[0013] Furthermore, through holes for the plastic drainage boards to pass through are provided on the peripheral side walls of the sealed box; the filter membranes on the plastic drainage boards placed in the sealed box are split in half along their widths into two reversely folded pulling parts, and the pulling parts pass through the strip grooves placed on adjacent through holes and are sewn and connected to the plastic drainage boards connected thereto; a spiral cover tightly screwed with it is provided on the top of the sealed box; sealing rings are fixedly connected to the inside of the spiral cover, the inner walls of the strip grooves, and the inner walls of the through holes.

[0014] Furthermore, a pressure relief and shock isolation area is provided between each diaphragm wall and the adjacent building, and a safety distance is provided between the pressure relief and shock isolation area and the adjacent pressure stabilizing and drainage layer; the pressure relief and shock isolation area includes a shock isolation blind ditch provided on the side of the building close to the adjacent diaphragm wall and arranged along its length direction, and a number of rows of vertical shafts arranged in sequence towards the adjacent pressure stabilizing and drainage layer are provided on the other side of the shock isolation blind ditch, the number of rows of the number of rows of vertical shafts ≥ 3, and the vertical shafts in adjacent two rows are staggered; the depth of the shock isolation blind ditch < the depth of the vertical shaft; filter soil geotextile bags are filled in the shock isolation blind ditch and each vertical shaft.

[0015] Furthermore, a construction method for a structure for stabilizing the water pressure around an underground project and reducing leakage is characterized in that: 1) Set a shock isolation and pressure control area around the building: Set the shock isolation blind ditch along the length direction on the side of the building close to the diaphragm wall, and set a number of rows of vertical shafts with different diameters and depths towards the diaphragm wall on the other side of the shock isolation blind ditch; 2) Construction of diaphragm wall, foundation pit and base: Conduct the construction of the diaphragm wall, and excavate the foundation pit within the area enclosed by the diaphragm wall. Pour permeable concrete in the foundation pit to form the base; 3) Set up a pressure stabilizing drainage layer on the outer periphery of each diaphragm wall: Open several rows of insertion ports on the outer periphery of each diaphragm wall. The adjacent two rows of insertion ports are staggered. Set several off-site drainage plates in each insertion port, which extend radially into the soil structure with the insertion port as the base point; Each insertion port is connected through the drainage ditch; 4) Set up a confined water isolation layer in the foundation pit: Set several cross-shaped floor drainage plates on the base. Set the vertical drainage plates perpendicular to both ends of each floor drainage plate. Each vertical drainage plate is laid along the height direction of the adjacent diaphragm wall to form a U-shaped channel; The upper part of each vertical drainage plate is connected to the drainage ditch interface in the adjacent insertion port; Set several transverse drainage plates connected to it at intervals along the width direction of the inner side of each diaphragm wall. The transverse drainage plates on the same horizontal plane on each diaphragm wall are connected end to end to form a horizontal annular channel. The horizontal annular channel and the U-shaped channel are connected and penetrated through several sealed boxes; Lay the waterproof layer on the other side of the U-shaped channel and the horizontal annular channel, lay the geotextile layer on the other side of the waterproof layer, and conduct the construction of the structural main body on the other side of the geotextile layer.

[0016] The present invention has the following beneficial effects: 1. By setting up a pressure stabilizing drainage layer on the outer periphery of the diaphragm wall, the present invention diverts and discharges the water around the diaphragm wall and on the ground surface, avoiding the water from gathering to form confined water, breaking through the diaphragm wall and seeping into the space between the diaphragm wall and the structural main body; By setting up a confined water isolation layer that wraps the structural main body on the periphery and at the bottom plate and is connected to the pressure stabilizing drainage layer, the pressure received by the structural main body can be evenly dispersed under the action of the self-weight of the structural main body, maintaining the force balance of the structural main body and reducing the generation of leakage points on the structural main body; Under the combined action of the pressure stabilizing drainage layer and the confined water isolation layer, the water pressure of the soil structure around the structural main body is regulated and controlled, maintaining the stability of the soil structure around the structural main body, and further maintaining the stability of the underground environment around the structural main body; By setting up a pressure reducing and vibration isolation area around the ground building, while increasing the groundwater discharge channel, the vibration wave generated by underground construction is effectively neutralized to stabilize the building; Through the use of these measures alone or in combination, the present invention realizes the overall rebalance of the surrounding environment during the underground construction process and after completion.

[0017] 2. The present invention controls the drainage channel area in the off-site drainage board in the pressure stabilizing drainage layer, the U-shaped channel and the horizontal annular channel in the pressure-bearing water-resistant layer and the steel-plastic composite tension rib belt laid therein. When the water pressure causes the main structure to float or settle on the peripheral side, the drainage channel area in the off-site drainage board, the U-shaped channel and the horizontal annular channel is controlled by pulling out the steel-plastic composite tension rib belt, so as to control the drainage volume of the pressure stabilizing drainage layer and the pressure-bearing water-resistant layer, and further alleviate the phenomenon of the main structure floating or settling.

[0018] 3. The cooperation of the U-shaped channel, the horizontal annular channel, the waterproof layer and the geotextile layer in the pressure-bearing water-resistant layer of the present invention makes it difficult for the water or slurry infiltrating into the diaphragm wall to leak into the main structure, and enables it to be evenly distributed around the main structure through the U-shaped channel and the horizontal annular channel under the action of the self-weight of the main structure, achieving the purpose of balanced stress on the peripheral side of the main structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 is a top view of the pressure stabilizing drainage layer.

[0021] Figure 3 is a schematic diagram of the connection relationship between the off-site drainage board and the insertion port.

[0022] Figure 4 is a schematic diagram of the structure of the pressure-bearing water-resistant layer.

[0023] Figure 5 is a schematic diagram of the connection relationship between the vertical drainage board and the horizontal drainage board.

[0024] Figure 6 is a schematic diagram of the connection relationship of the bottom plate drainage board.

[0025] Figure 7 is a structural sectional view of the surface reserved section.

[0026] Figure 8 is a top view sectional view of the sealed box.

[0027] Figure 9 is a side view sectional view of the sealed box.

[0028] Figure 10 is a top view of the shock isolation and pressure reduction area.

[0029] Figure 11 is a side view sectional view of the shock isolation and pressure reduction area.

[0030] The reference numerals in the drawings are shown as: 1. Foundation pit; 2. Diaphragm wall; 3. Base; 31. Bottom drainage board; 4. Structural main body; 5. Pressure stabilizing and drainage layer; 51. Insertion port; 511. Drainage ditch interface; 52. Drainage ditch; 53. Out-of-station drainage board; 54. Steel-plastic composite tension belt; 56. Tension part; 6. Confined aquitard; 61. Vertical drainage board; 62. Horizontal drainage board; 63. Waterproof layer; 64. Geotextile layer; 7. Surface reserved section; 71. Rubber cap; 72. Fastener; 8. Sealed box; 81. Through hole; 82. Groove; 83. Screw cap; 84. Reinforcing rib; 9. Pressure reducing and shock isolation area; 91. Shock isolation blind ditch; 92. Shaft. Detailed implementation mode

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Refer to Figures 1-11 , a structure for stabilizing the water pressure around an underground project and reducing leakage, including a foundation pit 1, a diaphragm wall 2 framed around the foundation pit 1, a base 3 formed by pouring permeable concrete in the foundation pit 1, and a structural main body 4 fixedly connected above the base 3; a pressure stabilizing and drainage layer 5 is provided on the outer side of each diaphragm wall 2 to timely drain the surface water and groundwater around the structural main body 4, avoiding their accumulation to form confined water and then finding a breakthrough point at the structural main body 4 to cause leakage; a confined aquitard 6 that wraps the bottom and side walls of the structural main body 4 is provided on the outer periphery of the structural main body 4. The confined aquitard 6 is placed in the foundation pit 1 and is connected to the pressure stabilizing and drainage layer 5. Under the action of the structural weight of the structural main body 4, the confined aquitard 6 transfers and disperses the water converging on the outer periphery of the structural main body 4, playing a role in controlling, digesting, and balancing the water pressure borne by the structural main body 4, preventing the bottom plate and side walls of the structural main body 4 from floating or settling due to sudden changes in water pressure, and then causing cracking, leakage and other situations.

[0033] The pressure stabilizing and drainage layer 5 drains the water converging on the outer periphery of the structural main body 4, and the confined aquitard 6 maintains the pressure stability on the outer periphery of the structural main body 4. Through the dual action of the pressure stabilizing and drainage layer 5 and the confined aquitard 6, the water pressure borne by the structural main body 4 and the diaphragm wall 2 around is guided and adjusted, balancing the interaction force between the structural main body 4 and the surrounding environment, and reducing the leakage risk of the structural main body 4.

[0034] Furthermore, the voltage-stabilizing drainage layer 5 includes a plurality of drainage insertion openings 51 formed on the ground surface, a drainage ditch 52 for connecting the plurality of drainage insertion openings 51, and a plurality of off-site drainage plates 53 arranged in each drainage insertion opening 51; the plurality of drainage insertion openings 51 are arranged outside the diaphragm wall 2 and in a direction away from the foundation pit 1, the distance between the row of drainage insertion openings 51 closest to the building and the building is ≥ the foundation depth of the building, the total distance between the plurality of drainage insertion openings 51 is ≥ the depth of the foundation pit 1, and adjacent two rows of drainage insertion openings 51 are arranged staggeredly; among them, the first row of drainage insertion openings 51 is arranged above the adjacent diaphragm wall 2, and the plurality of off-site drainage plates 53 in the first row of drainage insertion openings 51 are all closely attached to the diaphragm wall 2, the second row of drainage insertion openings 51 is arranged at a distance of 1 m from the first row of drainage insertion openings 51, and the adjacent setting distance of the third row and the subsequent plurality of drainage insertion openings 51 is between 1 m and 6 m.

[0035] Since the openings of the off-site drainage plates 53 on the ground should not be too many, and considering the complexity of the underground pipelines around the structure main body 4, overall consideration is taken and in order to reduce the construction difficulty of the ground openings, the adjacent drainage insertion openings 51 in each row are arranged at an interval of 10 m, and the plurality of off-site drainage plates 53 in each drainage insertion opening 51 extend radially into the soil layer structure with it as the base point. Among them, the number of off-site drainage plates 53 in each drainage insertion opening 51 is ≤ 10, the bottom distance between adjacent off-site drainage plates 53 is ≤ 2 m, and the construction depth of each off-site drainage plate 53 is at least 5 m deeper than the depth of the foundation pit 1; the voltage-stabilizing drainage layer 5 enables the surface water above the structure main body 4 to be discharged through the drainage ditch 52, and the groundwater outside the diaphragm wall 2 can be guided by the off-site drainage plates 53 and discharged into the drainage ditch 52 in a timely manner through each drainage insertion opening 51, and finally converge and flow into the three-stage sedimentation tank connected to the drainage ditch 52, avoiding the accumulation of surface water and groundwater in the soil layer structure, thereby maintaining the compressive stability of the soil layer structure outside the diaphragm wall 2 and achieving the purpose of anti-floating and anti-settlement.

[0036] Furthermore, the confined aquitard 6 includes a plurality of vertical drainage plates 61, a plurality of horizontal drainage plates 62 arranged in the foundation pit 1, and a plurality of bottom plate drainage plates 31 fixedly connected to the top of the base 3 and arranged in a horizontal and vertical cross manner; among them, two ends of each bottom plate drainage plate 31 are respectively provided with vertical drainage plates 61 perpendicular to and communicating with it to form a U-shaped channel; each vertical drainage plate 61 is laid along the height direction of the adjacent diaphragm wall 2, and the upper part of each vertical drainage plate 61 is communicated with the drainage ditch interface 511 in the adjacent drainage insertion opening 51 to discharge the confined water in the confined aquitard 6 into the drainage ditch 52; in order to facilitate mastering the working conditions of the vertical drainage plates 61 and organizing the maintenance required for the drainage process, the number of vertical drainage plates 61 connected to each drainage ditch interface 511 is ≤ 10.

[0037] On the inner side of each diaphragm wall 2, a number of horizontal drainage plates 62 are arranged at intervals along the height direction thereof. The horizontal drainage plates 62 on the same horizontal plane on each diaphragm wall 2 are connected end to end and communicate with each other to form a horizontal annular channel, and the horizontal annular channel is connected and communicated with the U-shaped channel; the setting intervals between adjacent vertical drainage plates 61, between adjacent horizontal drainage plates 62, and between adjacent bottom drainage plates 31 are ≤ 2 m; during construction, if the situation that the bottom drainage plates 31 need to be interrupted occurs, the interruption position can be set in the middle of the base 3, and the lapping length of the interruption position of the bottom drainage plates 31 is ≥ 2 m.

[0038] The horizontal annular channel cooperates with the U-shaped channel to wrap the side wall and the bottom of the structural main body 4. On the basis that the pressure stabilizing drainage layer 5 diverts and drains the groundwater outside the diaphragm wall 2, even if the groundwater breaks through and enters the diaphragm wall 2, it can be dispersed and discharged, so that the water pressure received by the periphery of the structural main body 4 is balanced, thereby reducing the occurrence of leakage points; in order to improve the drainage effect, along the length direction of each diaphragm wall 2, a vertically arranged first auxiliary drainage plate is laid every 5 m. The first auxiliary drainage plate is connected and communicated with the adjacent horizontal drainage plates 62, and its construction depth is at least 2 m deeper than the foundation pit 1; between each horizontal drainage plate 62, vertical drainage plate 61, first auxiliary drainage plate and the adjacent diaphragm wall 2, and between each bottom drainage plate 31 and the base 3, they are fixedly connected by a number of U-shaped nails; when excessive drainage causes the structural main body 4 to settle, part or all of the vertical drainage plates 61 can be sealed according to the needs to stop their drainage function to ensure the stability of the soil layer structure. At the same time, the horizontal annular channel and the U-shaped channel also play a role in reducing friction between the side wall of the structural main body 4 and the diaphragm wall 2, so as to prevent rigid contact and damage and cracking caused by settlement between the two concrete walls, and have the effect of energy dissipation and shock absorption.

[0039] When a large-scale leakage occurs in the structural main body 4, waterproof slurry grouting operations can be carried out into the horizontal annular channel and the U-shaped channel through a number of vertical drainage plates 61. Under the grouting pressure, the waterproof slurry is transported to the bottom plate and is evenly distributed around and at the bottom of the structural main body 4 by the self-weight action of the structural main body 4. After the waterproof slurry oozes out from the bottom drainage plates 31, it is evenly distributed in the base 3 and tightly combines with the base 3 to form a relatively firm integral body with a water-blocking effect, avoiding the situation that the local thickness of the base 3 varies greatly, increasing the strength of the base 3 and improving its bearing capacity.

[0040] Furthermore, the pressure-bearing waterproof layer 6 also includes a waterproof layer 63 arranged on one side of the horizontal annular channel and the U-shaped channel away from the underground continuous wall 2, and a geotextile layer 64 arranged on the other side of the waterproof layer 63; the other side of the geotextile layer 64 is provided with a structural main body 4 fixedly connected thereto. Among them, the overlap of the joints of the adjacent geotextiles is ≥20cm, and they are sewn by a geotextile sewing machine, and the joint positions should be staggered from the station compartment line, waterproof roll joints, post-casting strips, etc.; the geotextile layer 64 can prevent the concrete from penetrating the waterproof layer 63 and affecting the use effect of the horizontal annular channel and the U-shaped channel when the side wall and the bottom of the structural main body 4 are poured; the geotextile layer 64 forms a cement blanket after absorbing the concrete, which can avoid the loss of concrete slurry, honeycombs, rough surfaces, etc., which lead to quality risk problems, and enhance the shear resistance of the post-casting strips, compartment lines, and overlaps of the waterproof layer 63, so that the concrete quality and integrity of the bottom plate and the outer side of the side wall of the structural main body 4 are better, and the structural self-waterproofing ability is better, thereby reducing the quality risk of leakage and cracks in the structural main body 4.

[0041] Through the cooperation of the horizontal annular channel, the U-shaped channel, the waterproof layer 63 and the geotextile layer 64, a thick flexible water-permeable buffer pad is formed, so that the pressure generated by high-pressure water around and at the bottom of the structural body 4 can be flexibly buffered, diffused, transmitted, decomposed and consumed under the action of the deadweight of the structural body 4. At the same time, the high-pressure water is discharged to the drainage ditch 52 through the horizontal annular channel and the U-shaped channel to avoid direct impact or damage to the structural body 4 due to excessive local water pressure, resulting in internal leakage.

[0042] Furthermore, the upper parts of the off-site drainage board 53 and the vertical drainage board 61 are provided with a surface reserved section 7, the surface reserved section 7 is placed in the adjacent insertion opening 51, and the length of the surface reserved section 7 is ≥1m; when the ground around the structural body 4 sinks or over-drainage occurs, the off-site drainage board 53 and the vertical drainage board 61 need to be sealed: the surface reserved sections 7 of the off-site drainage board 53 and the vertical drainage board 61 are folded in half respectively and rubber caps 71 are sleeved on their outer peripheries, and fasteners 72 are sleeved on the lower parts of the rubber caps 71. The fasteners 72 can be made of steel sealing rings or self-locking nylon tie to be fastened and fixed, thereby stopping the drainage function of the off-site drainage board 53 and the vertical drainage board 61, and achieving stability of the soil structure.

[0043] Furthermore, the external drainage board 53, vertical drainage board 61, horizontal drainage board 62, bottom plate drainage board 31, and first auxiliary drainage board all give priority to the solid-base plastic drainage board with filter membrane used for soft foundation treatment. One or two additional plastic drainage boards can be installed on one side of the plastic drainage board placed at the construction joint, the junction of the compartment section, and the joint of the underground continuous wall 2 to increase its drainage capacity and reduce its leakage risk. Among them, the external drainage board 53 and the vertical drainage board 61 are both coated with plastic-steel composite tensioning belts 54 to increase their strength to prevent them from being squeezed, deformed, or even broken during the construction process.

[0044] Furthermore, between the horizontal drainage board 62 and the vertical drainage board 61, between the horizontally arranged and staggered bottom drainage boards 31, between the bottom drainage board 31 and the vertical drainage boards 61 at both its ends, between the first auxiliary drainage board and the horizontal drainage board 62, etc., the plastic drainage boards arranged crosswise are all connected and penetrated through the sealed box 8: through holes 81 for the plastic drainage boards to pass through are provided on the peripheral side walls of the sealed box 8; the filter membrane placed in the sealed box 8 is split in half along the width direction of the plastic drainage board into two pulling parts 56 that are folded in opposite directions. After passing through the strip grooves 82 placed on adjacent through holes 81, the pulling parts 56 are stitched and connected to the plastic drainage boards connected thereto and form a channel for the reinforcing rib 84 to pass through. The reinforcing rib 84 can be hard plastic, nylon rope, hybrid fiber rope, steel-plastic tape, etc. For example, the nylon rope is sequentially passed through each channel and then tied and tightened, so as to stably connect the pulling part 56 with the filter membrane connected thereto, prevent the filter membrane from being torn or broken due to large tensile force, and affect the drainage effect of the plastic drainage board; a spiral cover 83 that is threadedly matched and fastened to the top of the sealed box 8 is provided. Sealing rings are fixedly connected to the inside of the spiral cover 83, the inner wall of the strip groove 82, and the inner wall of the through hole 81 to enhance the sealing effect of the sealed box 8 and prevent water from seeping out.

[0045] The length of the steel-plastic composite tension belt 54 laid in the off-site drainage board 53 and the vertical drainage board 61 is ≥5m. After the construction of the structural main body 4 is completed, the drainage channel area in the off-site drainage board 53 and the vertical drainage board 61 can be controlled by adjusting the length of the steel-plastic composite tension belt: If it is found that the drainage volume does not meet the expected requirements or the water pressure from the periphery is still very high, on the basis of not damaging the core plates of the off-site drainage board 53 and the vertical drainage board 61, the steel-plastic composite tension belt is pulled outwards to increase the drainage channel area to increase the drainage volume. When necessary, active pumping drainage can be assisted by a vacuum pump to increase the drainage volume of the pressure stabilizing drainage layer 5 and the pressure-bearing water isolation layer 6 to meet the expected requirements and achieve the purpose of controlling the floating of the structural main body 4.

[0046] When the pressure stabilizing drainage layer 5 and the pressure-bearing water isolation layer 6 cause excessive groundwater drainage, after destroying the protrusions for drainage on the core plates in the off-site drainage board 53 and the vertical drainage board 61, the steel-plastic composite tension belt is pulled outwards to make the core plate at the damaged protrusion fit with the adjacent filter membrane, thereby reducing the drainage channel area to weaken the drainage volume; when necessary, the core plates in the off-site drainage board 53 and the vertical drainage board 61 can be completely removed to close the drainage channel and further reduce the drainage volume to avoid excessive drainage causing settlement; if underground settlement and uncontrollable drainage occur, the off-site drainage board 53 and the vertical drainage board 61 can be pulled out from the soil layer structure, and the soil layer structure about 3m deep into the ground surface can be grouted and reinforced to ensure the safety of the structural main body 4 and the surrounding buildings and relieve the settlement situation.

[0047] In the above situation, the extraction length of the steel-plastic composite tie bar each time ≤ 50 cm, and at the same time, it is necessary to ensure that the length of the steel-plastic composite tie bar remaining in the external drainage board 53 or the vertical drainage board 61 ≥ 100 cm.

[0048] Furthermore, a pressure relief and shock isolation zone 9 is provided between each diaphragm wall 2 and the adjacent building, and a safety distance is provided between the pressure relief and shock isolation zone 9 and the adjacent pressure stabilizing drainage layer 5; among them, the pressure relief and shock isolation zone 9 includes a shock isolation blind ditch 91 provided on the side of the building close to the adjacent diaphragm wall 2 and arranged along its length direction, and on the other side of the shock isolation blind ditch 91, a number of rows of vertical shafts 92 are provided in sequence in the direction of the adjacent pressure stabilizing drainage layer 5, the number of rows of the number of rows of vertical shafts 92 ≥ 3, the spacing between adjacent two rows of vertical shafts 92 ≥ 2 m, and the vertical shafts 92 in adjacent two rows are arranged staggeredly; the depth of the shock isolation blind ditch 91 < the depth of the vertical shaft 92, and both the shock isolation blind ditch 91 and each vertical shaft 92 are filled with filter geotextile bags, and the geotextile bags are filled with pervious materials such as sand and gravel.

[0049] Through the shock isolation blind ditches 91 and vertical shafts 92 with different depths, the suddenly increased groundwater pressure caused by the construction of the main structure 4 is relieved, so that it can be released and discharged through the vertical shafts 92, achieving the purpose of controlling and reducing the excess pressure generated during the construction processes such as underground engineering plugging grouting, high-pressure jet grouting piles, and shield underground tunneling. At the same time, it can also reduce and reduce the vibration impact during the construction process of underground engineering. A number of vertical shafts 92 close to the building can be the wells with the largest diameter, and their depth ≥ the foundation depth of the building; a number of vertical shafts 92 close to the diaphragm wall 2 are the wells with the second largest diameter, and their depth ≥ the depth of the foundation pit 1; a number of vertical shafts 92 placed between the two are the wells with the smallest diameter, and their depth is at least 2 m deeper than the depth of the wells with the second largest diameter. By making the depths and diameters of a number of vertical shafts 92 different, the vibration waves generated by underground construction are effectively neutralized, the impact on the ground is reduced, and thus the impact of the construction process of the underground main structure 4 on the surrounding environment and construction risks are reduced.

[0050] Furthermore, a construction method for a structure that stabilizes the water pressure around an underground project and reduces leakage specifically includes the following steps: 1) Set up a shock isolation and pressure control area around the building: Set up a shock isolation blind ditch 91 on the side of the building close to the diaphragm wall 2 along its length direction, and set up a number of rows of vertical shafts 92 with different diameters and depths on the other side of the shock isolation blind ditch 91 in the direction of the diaphragm wall 2; 2) Construction of the diaphragm wall 2 and the base 3 of the foundation pit 1: Carry out the construction of the diaphragm wall 2, and excavate the foundation pit 1 within the enclosed area of the diaphragm wall 2, and pour permeable concrete in the foundation pit 1 to form the base 3; 3) A pressure stabilizing and drainage layer 5 is arranged on the outer periphery of each diaphragm wall 2: A number of rows of insertion openings 51 are opened on the outer periphery of each diaphragm wall 2, and two adjacent rows of insertion openings 51 are arranged staggeredly. A number of off-site drainage plates 53 that radially extend into the soil layer structure with each insertion opening 51 as the base point are arranged in each insertion opening 51; Each insertion opening 51 is communicated through a drainage ditch 52; 4) A confined aquiclude 6 is arranged in the foundation pit 1: A number of cross-shaped bottom drainage plates 31 are arranged on the base 3. Vertical drainage plates 61 perpendicular to each bottom drainage plate 31 are arranged at both ends of each bottom drainage plate 31. Each vertical drainage plate 61 is laid along the height direction of the adjacent diaphragm wall 2 to form a U-shaped channel; The upper part of each vertical drainage plate 61 is communicated with a drainage ditch interface 511 in the adjacent insertion opening 51; A number of transverse drainage plates 62 connected to it are arranged at intervals along the width direction of the inner side of each diaphragm wall 2. The transverse drainage plates 62 on the same horizontal plane on each diaphragm wall 2 are connected end to end to form a horizontal annular channel; The U-shaped channel and the horizontal annular channel are connected and penetrated through a number of sealed boxes 8; A waterproof layer 63 is laid on the other side of the U-shaped channel and the horizontal annular channel, a geotextile layer 64 is laid on the other side of the waterproof layer 63, and the structure main body 4 is constructed on the other side of the geotextile layer 64.

[0051] The working principle of the present invention: The present invention is suitable for all underground projects such as subway stations, tunnels, basements, utility tunnels, bridge abutments, etc. Taking the subway station as an example for illustration.

[0052] See Figures 1-11 , before the construction of the diaphragm wall 2, a shock-absorbing blind ditch 91 is arranged along the length direction on one side of the building close to the diaphragm wall 2, and a number of rows of vertical shafts 92 extending towards the diaphragm wall 2 are arranged on the other side of the shock-absorbing blind ditch 91, so that the distance between two adjacent rows of vertical shafts 92 ≥ 2m, and the vertical shafts 92 in two adjacent rows are arranged staggeredly. A number of rows of vertical shafts 92 form a shock isolation and pressure control area. At the same time, a number of filter soil geotextile bags are filled in each vertical shaft 92 and the shock-absorbing blind ditch 91 to facilitate drainage and prevent the surrounding soil from squeezing the vertical shaft 92 and causing deformation.

[0053] When three rows of vertical shafts 92 are arranged, the diameter of the row of vertical shafts 92 closest to the building can be ≥ 400mm, and its depth ≥ the foundation depth of the building; The diameter of the row of vertical shafts 92 closest to the foundation pit 1 ≤ 200mm, and its depth ≥ the depth of the foundation pit 1; The diameter of the row of vertical shafts 92 placed in the middle ≤ 150mm, and its depth is about 2m less than the depth of the vertical shaft 92 closest to the foundation pit 1.

[0054] After the construction of several rows of vertical shafts 92 is completed, the diaphragm wall 2 is constructed, and the foundation pit 1 is excavated within the area enclosed by the diaphragm wall 2. The width and length of the diaphragm wall 2 can be increased by 1 cm - 5 cm to ensure the structural clearance of the station and reduce the risk of underground subsidence. A base 3 is formed by pouring permeable concrete in the foundation pit 1. At the same time, the seismic isolation and pressure control area can neutralize the vibration waves generated during construction and weaken the impact of construction on the ground and soil layer structure.

[0055] During the construction process, the pressure stabilizing and drainage layer 5 guides and discharges the groundwater and surface water outside the periphery of the diaphragm wall 2 to maintain the stability of the soil layer structure.

[0056] After the construction of the structural main body 4 is completed, the pressure stabilizing and drainage layer 5 continues to drain water. When high-pressure water invades between the diaphragm wall 2 and the structural main body 4, and between the structural main body 4 and the base 3, it is blocked outside the structural main body 4 through the waterproof layer 63 and the geotextile layer 64. And the confined water can be evenly distributed around the structural main body 4 under the action of the self-weight of the structural main body 4 via the U-shaped channel and the horizontal annular channel, and finally drained into the drainage ditch 52 to be decomposed and consumed, so that the pressure on the periphery of the structural main body 4 is balanced and leakage points are not easily formed.

[0057] During the construction and use of the structural main body 4, the settlement and groundwater level of the structural main body 4, the precipitation safety area and the surrounding environment are continuously monitored. If abnormal settlement of the ground and buildings is found, and the surrounding groundwater level drops, the drainage conditions of the vertical drainage board 61 and the off-site drainage board 53 are checked in time: If it is found that the drainage volume does not meet the expected requirements or the water pressure from the outside is still very high, without damaging the core board protrusions, the steel-plastic composite tension belts in the vertical drainage board 61 and the off-site drainage board 53 are pulled outwards to increase the drainage channels. If necessary, a vacuum pump is used for active drainage to increase the drainage volume of the vertical drainage board 61 and the off-site drainage board 53, so as to achieve the purpose of controlling the floating of the structural main body 4.

[0058] If the groundwater is over-drained due to the vertical drainage board 61 and the off-site drainage board 53, the protrusions for drainage on the core board in the vertical drainage board 61 and the off-site drainage board 53 can be damaged so that the core board at the damaged protrusion fits with the filter membrane, reducing the drainage channels, thereby controlling the drainage volume; if the drainage effect is not good, if necessary, all the core boards in the vertical drainage board 61 and the off-site drainage board 53 are damaged and removed to further control the drainage volume and avoid excessive drainage causing settlement.

[0059] When the land subsidence and drainage are uncontrollable, some or all of the vertical drainage plates 61 and the off-site drainage plates 53 can be extracted, and the soil layer structure at a depth of about 3 m from the ground surface can be grouted and reinforced. Then, an impermeable geotextile is fully paved on the ground surface and steel plates are covered until the reinforced concrete solidifies to maintain the stability of the soil layer structure.

[0060] The above are only the embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A structure for stabilizing water pressure around underground projects and reducing leakage, comprising a foundation pit (1), an underground continuous wall (2) framed around the foundation pit (1), a base (3) formed by pouring permeable concrete and arranged in the foundation pit (1), and a structural body (4) fixedly connected to the top of the base (3), characterized in that: A plurality of drainage channels are provided in the soil layer structure outside each underground continuous wall (2), and the drainage channels are connected to the drainage ditch (52) arranged on the surface through the insertion opening (51), and the insertion opening (51), the drainage ditch (52) and the plurality of drainage channels form a pressure-stabilizing drainage layer (5); a pressure-bearing waterproof layer (6) is provided on the outer periphery of the structural body (4), and the pressure-bearing waterproof layer (6) comprises a horizontal annular channel framed around the structural body (4), and a U-shaped channel wrapped around the periphery and bottom of the structural body (4), and the horizontal annular channel and the U-shaped channel are interconnected and interlinked; the U-shaped channel is placed above the base (3), and the output end of the U-shaped channel is connected to the drainage ditch (51); the horizontal annular channel and the U-shaped channel are both fixedly connected to the inner side of the underground continuous wall (2).

2. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 1, characterized in that: A plurality of rows of the punched holes (51) are arranged on the outer surface of each underground continuous wall (2) extending in a direction away from the foundation pit (1); the plurality of rows of the punched holes (51) are connected via the drainage ditch (52); the drainage ditch (52) is connected to the tertiary sedimentation tank; the sum of the spacings between the plurality of rows of the punched holes (51) is ≥ the depth of the foundation pit (1), and two adjacent rows of the punched holes (51) are arranged in a staggered manner; a plurality of drainage channels are arranged in each of the punched holes (51), and the plurality of drainage channels are radially extended into the soil layer structure with the punched holes as the base point; the drainage channels are external drainage boards (53), and the number of external drainage boards (53) in each punched hole (51) is ≤10; the bottom spacing of adjacent external drainage boards (53) is ≤2m.

3. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 2, characterized in that: The U-shaped channel comprises a plurality of bottom plate drainage boards (31) fixedly connected to the top of the base (3) and arranged in a cross-direction, and vertical drainage boards (61) perpendicular to and in communication with the bottom plate drainage board (31) are respectively arranged at both ends of each bottom plate drainage board (31); each vertical drainage board (61) is laid along the height direction of the adjacent underground continuous wall (2), and the upper part of each vertical drainage board (61) is connected to the drainage ditch interface (511) in the adjacent insertion opening (51); the horizontal annular channel comprises a plurality of transverse drainage boards (62) arranged at intervals along the height direction of the inner side of each underground continuous wall (2), and the transverse drainage boards (62) arranged on the same horizontal plane on each underground continuous wall (2) are connected end to end and intersected; the vertical drainage boards (61) and the transverse drainage boards (62) are both placed in the foundation pit (1).

4. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 3, characterized in that: The upper parts of the off-site drainage board (53) and the vertical drainage board (61) are both provided with a surface reserved section (7), the surface reserved section (7) is placed in the adjacent insertion opening (51), and the length of the surface reserved section (7) is ≥1m; the surface reserved sections (7) of the off-site drainage board (53) and the vertical drainage board (61) are respectively folded in half and a rubber cap (71) is sleeved on the outer periphery thereof, and a fastener (72) is sleeved on the lower part of the rubber cap (71).

5. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 4, characterized in that: The exterior drainage board (53) and the vertical drainage board (61) are both provided with plastic-steel composite tensioning bands (54) to increase their strength.

6. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 5, characterized in that: The pressure-bearing waterproof layer (6) further comprises a waterproof layer (63) arranged on the side of the horizontal annular channel and the U-shaped channel away from the underground continuous wall (2), and a geotextile layer (64) arranged on the other side of the waterproof layer (63); the other side of the geotextile layer (64) is provided with a structural body (4) fixedly connected thereto.

7. The structure for stabilizing water pressure around underground engineering and reducing leakage according to claim 3, characterized in that: The off-site drainage board (53), the vertical drainage board (61), the horizontal drainage board (62), and the bottom plate drainage board (31) are all solid-base plastic drainage boards with filter membranes used for soft foundation treatment; the plastic drainage boards arranged crosswise with each other are connected and penetrated by a sealed box (8).

8. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 7, characterized in that: The sealed box (8) is provided with through holes (81) on the four side walls thereof for the plastic drain board to pass through; the filter membrane on the plastic drain board placed in the sealed box (8) is divided into two oppositely folded pulling parts (56) in half along its width direction; the pulling parts (56) pass through the grooves (82) placed on the adjacent through holes (81) and are sewn to the plastic drain board connected thereto; the sealed box (8) is provided with a screw cover (83) on the top thereof and is screwed together with the screw cover; the inside of the screw cover (83), the inner wall of the grooves (82) and the inner wall of the through holes (81) are all fixedly connected with sealing rings.

9. The structure for stabilizing water pressure around underground projects and reducing leakage according to claim 1, characterized in that: A pressure-reducing and seismic isolation zone (9) is provided between each underground continuous wall (2) and the adjacent building, and a safety distance is provided between the pressure-reducing and seismic isolation zone (9) and the adjacent pressure-stabilizing and drainage layer (5); the pressure-reducing and seismic isolation zone (9) comprises a shock-absorbing blind ditch (91) provided on one side of the building close to the adjacent underground continuous wall (2) and along its length direction, and a plurality of rows of vertical shafts (92) are provided on the other side of the shock-absorbing blind ditch (91) and are arranged in sequence in the direction of the adjacent pressure-stabilizing and drainage layer (5), the number of rows of vertical shafts (92) being ≥3, and the vertical shafts (92) in two adjacent rows being arranged in a staggered manner; the depth of the shock-absorbing blind ditch (91) being less than the depth of the vertical shafts (92); and the shock-absorbing blind ditch (91) and each of the vertical shafts (92) are filled with water-filtering geotextile bags.

10. A construction method for a structure for stabilizing water pressure around underground projects and reducing leakage according to claims 1-9, characterized in that: 1) Setting a seismic isolation and pressure control zone (9) around the building: setting a seismic blind ditch (91) along the length direction of the building on one side close to the underground continuous wall (2), and setting a plurality of rows of vertical shafts (92) of different diameters and depths on the other side of the seismic blind ditch (91) in the direction of the underground continuous wall (2); 2) Construction of underground continuous wall (2), foundation pit (1), and base (3): Construction of the underground continuous wall (2) is carried out, and the foundation pit (1) is excavated in the area enclosed by the underground continuous wall (2), and permeable concrete is poured in the foundation pit (1) to form the base (3); 3) a pressure-stabilizing drainage layer (5) is arranged on the outer periphery of each underground continuous wall (2): a plurality of rows of insertion holes (51) are opened on the outer periphery of each underground continuous wall (2), two adjacent rows of the insertion holes (51) are arranged in a staggered manner, and a plurality of external drainage boards (53) are arranged in each insertion hole (51) and radially extend into the soil structure with the insertion hole (51) as a base point; the insertion holes (51) are connected to each other through the drainage ditch (52); 4) A pressure-bearing waterproof layer (6) is provided in the foundation pit (1): a plurality of bottom plate drainage boards (31) are provided on the base (3) in a horizontal and vertical manner, and vertical drainage boards (61) perpendicular to the bottom plate drainage boards (31) are provided at both ends of each bottom plate drainage board (31), and each vertical drainage board (61) is laid along the height direction of the adjacent underground continuous wall (2) to form a U-shaped channel; the upper part of each vertical drainage board (61) is connected to the drainage ditch interface (511) in the adjacent insertion opening (51); along each side of the underground continuous wall (2 ) are arranged at intervals in the width direction of the inner side thereof and connected thereto; the transverse drainage boards (62) placed on the same horizontal plane on each underground continuous wall (2) are connected end to end to form a horizontal annular channel; the horizontal annular channel and the U-shaped channel are connected and interlinked through the plurality of sealed boxes (8); the waterproof layer (63) is laid on the other side of the U-shaped channel and the horizontal annular channel, the geotextile layer (64) is laid on the other side of the waterproof layer (63), and the structural main body (4) is constructed on the other side of the geotextile layer (64).

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