Displacement type anti-floating pressure relief device and design method of anti-floating pressure relief structure

Abstract

A displacement type anti-floating pressure relief device comprises a sleeve 1 fixed in a foundation 6 at the bottom of a building, and an opening is formed in the lower portion of the sleeve 1. The bracket 2 is fixed in a foundation soil layer below the foundation 6; a drainage pipe 4 is further fixed in the foundation 6, the water outlet end of the drainage pipe 4 extends out of the top of the foundation 6, the drainage end 40 of the drainage pipe 4 penetrates through and extends into the sleeve 1, the top of the support 2 is fixedly connected with a displacement type drainage switch 3, the top of the displacement type drainage switch 3 is provided with a spring 30, the maximum elongation of the spring 30 is adjustable, and the top of the spring 30 is fixedly connected with a spring top plate 31. The spring top plate 31 vertically corresponds to the drainage end 40 of the drainage pipe 4, and when the spring top plate 31 abuts against the water inlet end of the drainage pipe 4, the drainage end 40 of the drainage pipe 4 is blocked.

Description

Technical Field

[0001] The present invention relates to the technical field of underground buildings, and in particular to a displacement type anti-floating and pressure relief device and a design method of an anti-floating and pressure relief structure. Background Art

[0002] When underground buildings have groundwater, buoyancy will be generated. If the buoyancy value exceeds the sum of the building's own weight and the ballast weight, it will cause the building to lift up and cause damage. Therefore, underground projects will take measures such as increasing the ballast weight and setting anti-floating anchors according to the determined anti-floating design water level to resist water buoyancy. There are also some drainage and pressure relief methods, which release pressure when the water pressure exceeds the limit, control the water buoyancy not to exceed the limit, and ensure the safety of the building. The "drainage and pressure relief method" uses pressure as the control indicator; at the same time, in order to avoid soil loss, filter cloth and other measures are used to prevent soil particles from being carried away by water. The applicant has applied for patent number ZL 2022 22034114.0, which discloses an anti-floating deformation control system for underground buildings under conditions of excessive water buoyancy, which controls the deformation of the building under conditions of excessive buoyancy.

[0003] The principle of the above structure is that when encountering extreme conditions, the water level rises, and the water buoyancy causes elastic deformation of the underground building structure, a cavity is formed between the raft foundation cushion layer and the foundation. The cavity is filled with groundwater, and the drainage pipe is lifted upward with the main body to discharge the water in the underground cavity between the foundation and the foundation. That is, when the water level rises, drainage is immediately carried out.

[0004] When the applicant filed the above application, it was still in the conceptual stage. However, during actual use, the following problems were discovered: when the building was just floating up, the height of the cavity formed was relatively low, and the flow rate per unit time (Q) = flow velocity (v) × area (A). The flow rate of groundwater seeping out of the soil layer was certain. The low height of the cavity resulted in a smaller cross-sectional area of ​​the channel (cavity) for water to flow to the drainage pipe, which led to a higher water flow rate in the cavity. The higher water flow rate would cause the mud and sand in the foundation to be washed away by the water flow, which would not only lead to the loss of foundation soil, but also make the drainage pipe more prone to blockage.

[0005] Based on the above problems, improvements are needed. On the one hand, the drainage pipes should be improved so that the water will not be drained immediately when the building just floats up, but can be drained when the building floats up to a specific height according to the designer's design; on the other hand, how to determine the specific height to which the building floats when drainage begins so that the cross-sectional area of ​​the channel (cavity) is sufficient to reduce the flow velocity v to a level that will not carry away excessive sediment are two technical problems to be solved by the present invention. Summary of the Invention

[0006] In order to solve the problem that a drainage pipe can be designed to drain water when it floats to a specific height on a building according to the designer's design, the present invention provides a displacement type anti-floating and pressure relief device and a design method for an anti-floating and pressure relief structure.

[0007] The purpose of the present invention is achieved in the following way: a displacement type anti-floating and pressure relief device, comprising a sleeve 1 fixed in a foundation 6 at the bottom of a building, with an opening at the bottom of the sleeve 1; and a bracket 2 fixed in the foundation soil layer below the foundation 6; a drain pipe 4 is also fixed in the foundation 6, the outlet end of the drain pipe 4 extends from the top of the foundation 6, the drainage end 40 of the drain pipe 4 passes through and extends into the sleeve 1, the top of the bracket 2 is fixedly connected to a displacement type drainage switch 3, a spring 30 is provided at the top of the displacement type drainage switch 3, the maximum elongation of the spring 30 is adjustable, the top of the spring 30 is fixedly connected to a spring top plate 31, the spring top plate 31 corresponds to the drainage end 40 of the drain pipe 4 up and down, and when the spring top plate 31 abuts against the water inlet end of the drain pipe 4, the drainage end 40 of the drain pipe 4 is blocked.

[0008] Furthermore, the displacement-type drainage switch 3 includes an upper support 22 and an elastic member detachably connected to the upper support 22; the upper support 22 includes at least one vertical steel plate 23 fixedly connected to the bracket 2, and the top of the vertical steel plate 23 is fixedly connected to the horizontal steel plate 25; the elastic member includes a spring bottom plate 26 abutting the top of the horizontal steel plate 25, the top of the spring bottom plate 26 is fixedly connected to the bottom end of the spring 30, the top of the spring 30 is fixedly connected to the spring top plate 31, the top of the spring top plate 31 is fixedly connected to the anti-leakage gasket 32, and the bottom of the spring top plate 31 is fixedly connected to the screw rod 33, the screw rod 33 passes downward through the spring bottom plate 26 and the horizontal steel plate 25 in turn, and is threadedly connected to an adjusting nut 34, so that the maximum elongation of the spring 30 can be adjusted by adjusting the position of the nut 34 on the screw rod 33 and cooperating with the limit of the bottom of the horizontal steel plate 25.

[0009] Furthermore, the upper support 22 and the elastic member are detachably connected, which means that: the horizontal steel plate 25 extends from the middle to the side through the horizontal open groove 24, the screw 33 between the spring base plate 26 and the adjusting nut 34 is installed into the upper support 22 through the horizontal open groove 24, and at least one limiting steel ball 27 is fixedly connected to the bottom of the spring base plate 26, and a hole 29 is set on the top of the horizontal steel plate 25 to cooperate with the limiting steel ball 27 for positioning.

[0010] Furthermore, a covering structure 5 is arranged in the foundation soil layer, and the covering structure 5 is covered on the outside of the bracket 2. The covering structure 5 includes a fragment layer 13 connected to the foundation soil of the foundation soil layer, and a permeable geotextile 12 is arranged between the fragment layer 13 and the foundation soil for limiting. A stainless steel grid mesh 14 is arranged in the fragment layer 13 for limiting, and the stainless steel grid mesh 14 is arranged around the outside of the bracket 2.

[0011] Furthermore, a reinforced concrete layer is set at the bottom of the fragment layer 13, and the permeable geotextile 12 and the stainless steel grid 14 are fixedly connected to the reinforced concrete layer. The reinforced concrete layer includes a concrete slab 11 and a steel mesh 10 covered in the concrete slab 11. A number of water inlet holes are set on the bracket 2, and a number of reserved steel bar holes 17 are set at the bottom of the bracket 2. The bottom of the bracket 2 is embedded in the concrete slab 11, and the steel bars that make up the steel mesh 10 pass through the reserved steel bar holes 17.

[0012] Furthermore, a circular ring 44 for the building surface layer is fixed on the foundation 6 at the top of the sleeve 1, a flange 41 is fixedly connected to the top of the sleeve 1, a blind plate 42 is fixedly connected to the top of the flange 41 by screws 43, and a water-stop steel plate 39 is fixedly connected to the outer periphery of the sleeve 1 body; a waterproof cushion layer 7 is fixed to the bottom of the foundation 6, and the waterproof cushion layer 7 is separated from the foundation soil layer when the building floats, and the bottom of the waterproof cushion layer 7 is fixedly connected to the cover plate 36 surrounding the sleeve 1, and two layers of studs 38 are fixed along the circumferential array on the outer periphery of the bottom of the sleeve 1, and the cover plate 36 is clamped between the two layers of studs 38.

[0013] Furthermore, the outer periphery of the bracket 2 is fixedly connected to the first compressive steel block 20, and the inner wall of the sleeve 1 is fixedly connected to the second compressive steel block 37. When the building is not floated, the first compressive steel block 20 abuts against the second compressive steel block 37.

[0014] Furthermore, the floating deformation limit of the building is Smax; the height difference from the height of the drainage end 40 when the building is not floating to the height difference when the drainage end 40 separates from the spring top plate 31 and starts to drain is the floating pressure relief value S, and the initial value of the floating deformation pressure relief is Smin, Smin≤S<Smax, where Smin=(K•i•A') / (C•v'), where K is the soil permeability coefficient of the foundation soil layer, i is the hydraulic gradient, A' is the area borne by the equipment, C is the perimeter of the area enclosed by the junction of the fragment layer 13 and the foundation soil, and v' is the non-erosion flow velocity determined according to the soil quality of the foundation soil.

[0015] A design method for an anti-floating and pressure-relieving structure including the above-mentioned displacement-type anti-floating and pressure-relieving device, the method comprising: designing and determining the number and location of the displacement-type pressure-relieving devices based on the underground building and geological conditions, calculating the building's floating deformation limit value Smax and the corresponding floating deformation and pressure-relieving initial value Smin at each displacement-type pressure-relieving device, ensuring that Smin is less than Smax; when Smin is found to be greater than Smax at a certain displacement-type anti-floating and pressure-relieving device, increasing the density of the displacement-type anti-floating and pressure-relieving devices near the location, reducing the equipment burden area A' of the displacement-type anti-floating and pressure-relieving device, and / or increasing the size of the area surrounded by the fragment layer 13 to increase the perimeter C, so that Smin is reduced to Smin<Smax; determining the value of S based on Smin, so that S=Smin or S is greater than Smin by 0-5mm, and ensuring that S<Smax; and adjusting the position of the adjusting nut 34 on the screw rod 33 according to the determined S value during actual installation to change the maximum extension of the spring 30, so that after the drain pipe 4 rises to a height S, it disengages from the spring top plate 31 and begins to drain.

[0016] Compared with the existing technology, the present invention sets a displacement-type drainage switch with an adjustable maximum extension to cooperate with the drainage pipe. The displacement amount of the drainage pipe from the displacement-type drainage switch can be pre-set. When the displacement amount is lower than the set displacement amount, the pressure will not be released. When the displacement amount exceeds the set displacement amount, the pressure will be released. The displacement and pressure relief are effectively combined, so that there is no need to drain the water when the building is just floating. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of the displacement type pressure relief device when draining water; Figure 2 is a structural schematic diagram of the cladding structure; Figure 3 is a schematic diagram of the structure of the bracket; Figure 4 This is a schematic diagram of the structure of the elastic part of the displacement type drain switch; Figure 5 This is a structural diagram of the upper support portion of the displacement type drain switch; Figure 6 It is a structural diagram of the sleeve; Figure 7 This is a schematic diagram of the critical state where the building is deformed upward and not depressurized; Figure 8 This is a schematic diagram of the building in its deformed state before it floats up; Figure 9 This is a schematic diagram of the displacement type drainage switch state, where Figure 9 .1 corresponds to Figure 8 state; Figure 9 .2 corresponds to Figure 7 state; Figure 9 .3 corresponding Figure 1 status.

[0018] Among them, sleeve 1, bracket 2, displacement type drainage switch 3, drainage pipe 4, covering structure 5, concrete foundation (raft slab) 6, cushion and waterproof layer 7, water cake 8, steel mesh 10, concrete slab 11, permeable geotextile 12, fragment layer 13, stainless steel grid 14, round steel pipe 15, base 16, reserved steel bar hole 17, rectangular hole 18, round hole 19, first compressive steel block 20, limit bar 21, upper support 2 2, vertical steel plate 23, horizontal opening groove 24, horizontal steel plate 25, spring bottom plate 26, limiting steel ball 27, round hole 28, hole 29, spring 30, spring top plate 31, anti-leakage gasket 32, screw 33, adjusting nut 34, round steel pipe 35, cover plate 36, second pressure-resistant steel block 37, stud 38, water-stop steel plate 39, drainage end 40, flange 41, blind plate 42, screw 43, building surface ring 44. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] In the present invention, unless otherwise expressly specified and limited, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] As attached Figure 1 As shown, a displacement type anti-floating pressure relief device includes a sleeve 1 fixed in a foundation 6 at the bottom of a building, the foundation 6 is a concrete foundation or a raft slab, and the sleeve 1 is preferably a steel cylinder structure with an opening at the bottom, and the sleeve 1 has an opening at the bottom; and a bracket 2 fixed in the foundation soil layer below the foundation 6; a drainage pipe 4 is also fixed in the foundation 6, the outlet end of the drainage pipe 4 extends from the top of the foundation 6 and is connected to a corresponding drainage ditch, etc., the drainage end 40 of the drainage pipe 4 passes through and extends into the sleeve 1, and is preferably opened downward, and the top of the bracket 2 is fixedly connected to a displacement type drainage switch 3, as shown in the attached figure. Figure 4As shown, a spring 30 is provided on the top of the displacement type drain switch 3, the maximum elongation of the spring 30 is adjustable, and the top of the spring 30 is fixedly connected to a spring top plate 31, which corresponds to the drainage end 40 of the drain pipe 4 up and down, and when the spring top plate 31 abuts against the water inlet end of the drain pipe 4, the drainage end 40 of the drain pipe 4 is blocked.

[0022] The sleeve 1 and the drain pipe 4 are integrated with the foundation raft 6. When the building is deformed, they rise and fall together, and the water is discharged smoothly during pressure relief and drainage. The size of the drain pipe is selected according to the drainage capacity.

[0023] Further, as attached Figure 4-5 As shown, the displacement type drain switch 3 includes an upper support 22 and an elastic member detachably connected to the upper support 22; the upper support 22 includes at least one vertical steel plate 23 fixedly connected to the bracket 2, preferably two pieces, and welded to the bracket 2, and the top of the vertical steel plate 23 is welded and fixedly connected to the horizontal steel plate 25; the elastic member includes a spring bottom plate 26 abutting the top of the horizontal steel plate 25, the top of the spring bottom plate 26 is fixedly connected to the bottom end of the spring 30, the top of the spring 30 is fixedly connected to the spring top plate 31, the top of the spring top plate 31 is fixedly connected to a water-proof gasket 32, the water-proof gasket 32 ​​is preferably made of soft and impermeable rubber material, and the bottom of the spring top plate 31 is fixedly connected to a screw 33. The screw 33 is arranged in the spring 30, and the screw 33 passes through the spring bottom plate 26 and the horizontal steel plate 25 downward in sequence, and is threadedly connected with the adjusting nut 34, so that by adjusting the position of the nut 34 on the screw 33 and the limiting cooperation with the bottom of the horizontal steel plate 25, a gasket is preferably fixed on the top of the adjusting nut 34, which is placed between the adjusting nut 34 and the bottom of the horizontal steel plate 25 to achieve the adjustment of the maximum elongation of the spring 30. For example, by screwing the adjusting nut 34 upward, the spring 30 is further compressed, reducing the maximum elongation of the spring 30, that is, reducing the maximum height of the spring top plate 31. At this maximum height, the drainage end 40 of the drain pipe 4 can be separated from the spring top plate 31.

[0024] The displacement-type drain switch 3 remains closed and does not drain water until the building's upward deformation reaches the initial upward deformation pressure relief value. Once the value exceeds this, it opens and drains water. When closed, it seals the drain, achieved by waterproof gasket 32 ​​and appropriate pressure (spring 30 stiffness and displacement). The position of nut 34 on screw 33 controls the expansion and contraction of spring 30, creating a displacement-type switch. Preferably, after installation, the expansion and contraction of spring 30 (the nut's positioning) equals the "initial upward deformation pressure relief value Smin" (details described below).

[0025] Furthermore, the upper support (22) and the elastic member are detachably connected in that: the horizontal steel plate 25 extends a horizontal opening slot 24 from the middle to the side, the slot width is greater than or equal to the diameter of the screw 33, the screw 33 between the spring base plate 26 and the adjusting nut 34 is installed in the middle of the upper support 22 through the horizontal opening slot 24, at least two limiting steel balls 27 are fixedly connected to the bottom of the spring base plate 26, and a hole 29 is provided on the top of the horizontal steel plate 25 for cooperating with the limiting steel balls 27 to position the elastic member, so that the elastic member can be separated and adjusted.

[0026] Further, as attached Figure 2 As shown, a covering structure 5 is provided in the foundation soil layer, and the covering structure 5 is covered on the outside of the bracket 2. The covering structure 5 includes a fragment layer 13 connected to the foundation soil of the foundation soil layer. The fragment layer 13 is preferably composed of materials such as sand and gravel. Compared with the foundation soil, it is less likely to be carried away by water. A permeable geotextile 12 is provided between the fragment layer 13 and the foundation soil to limit the loss of the original soil. A stainless steel grid 14 is provided in the fragment layer 13 to limit the flow of fragments. The stainless steel grid 14 is arranged around the outside of the bracket 2, and sufficient space can be left between the stainless steel grid 14 and the bracket 2 to form a water storage cavity; that is, the fragment layer 13 is separated from the foundation soil by the stainless steel grid 14. The annular cavity formed by the permeable geotextile 12 is covered, and the covering structure 5 is permeable and connected to the foundation soil through the covering structure 5. When the building floats and deforms, it remains motionless with the foundation soil, so that the water cake 8 is formed smoothly. The permeable geotextile 12, sand, gravel 13 and other materials prevent soil particles from being carried away by water. A cavity with water but no soil is formed in the grid mesh 14, which gathers water and facilitates smooth discharge of water. Preferably, the fragment layer 13 is as shown in the figure, and is a stepped / conical structure with a diameter gradually decreasing from top to bottom. The purpose of this setting is to increase the top range of the fragment layer 13. The advantages brought by this setting involve another important feature, which will be described in detail later.

[0027] Furthermore, a reinforced concrete layer is provided at the bottom of the fragment layer 13, and the bottom of the permeable geotextile 12 and the bottom of the stainless steel grid 14 are fixedly connected to the reinforced concrete layer. The reinforced concrete layer includes a concrete slab 11 and a steel mesh 10 wrapped in the concrete slab 11. Figure 3 As shown, the bracket 2 preferably includes a main body of a round steel tube 15, and the round steel tube 15 is provided with a plurality of water inlet holes, preferably including a rectangular hole 18 at the bottom and a circular hole 19 in the middle as shown in the figure. A plurality of reserved steel bar holes 17 are provided at the bottom of the bracket 2. The bottom of the bracket 2 is embedded in the concrete slab 11, and the steel bars constituting the steel mesh 10 pass through the reserved steel bar holes 17. During production, the steel mesh (truss) of the component is set through the bracket 2. When pouring concrete, the concrete slurry covers the base 16 at the bottom of the round steel tube 15 to form a stable integrated structure.

[0028] Further, as attached Figure 6As shown, a circular ring 44 for building surface layer is fixed on the foundation 6 at the top of the sleeve 1 (according to the requirements of building decoration, the circular ring 44 can be changed to an openable "well cover"), and the circular ring 44 for building surface layer is located at the top of the foundation 6. The top of the sleeve 1 is fixedly connected to the flange 41, and the top of the flange 41 is fixedly connected to the blind plate 42 by screws 43. The outer periphery of the sleeve 1 is fixedly connected to the water-stop steel plate 39 to prevent water from leaking upward from the outside of the sleeve 1; a waterproof cushion layer 7 is fixed to the bottom of the foundation 6. When the building floats, the waterproof cushion layer 7 is separated from the foundation soil layer. The characteristics of the waterproof cushion layer 7 and the separation from the foundation soil layer are prior art. The bottom of the waterproof cushion layer 7 is fixedly connected to the cover plate 36 surrounding the sleeve 1. Two layers of studs 38 are fixed in a circumferential array on the outer periphery of the bottom of the sleeve 1, and the cover plate 36 is clamped between the two layers of studs 38.

[0029] Furthermore, the outer periphery of the bracket 2 is fixedly connected to the first compressive steel block 20, and the inner wall of the sleeve 1 is fixedly connected to the second compressive steel block 37. When the building is not floated, the first compressive steel block 20 abuts against the second compressive steel block 37, and plays a supporting role when the building is not floated; preferably, the outer periphery of the bracket 2 is fixedly connected to the limit bar 21, and the limit bar 21 abuts against the inner wall of the sleeve 1, so that the sleeve 1 and the bracket 2 form a sliding fit to prevent the displacement type drainage switch 3 from shifting.

[0030] Furthermore, the floating deformation limit of the building is Smax; the height difference from the height of the drainage end 40 when the building is not floating to the height difference when the drainage end 40 separates from the spring top plate 31 and starts to drain is the floating pressure relief value S, and the initial value of the floating deformation pressure relief is Smin, Smin≤S<Smax, where Smin=(K•i•A') / (C•v'), where K is the soil permeability coefficient of the foundation soil layer, i is the hydraulic gradient, A' is the area borne by the equipment, C is the perimeter of the area enclosed by the junction of the fragment layer 13 and the foundation soil, and v' is the non-erosion flow velocity determined according to the soil quality of the foundation soil.

[0031] Related calculation principles or formulas: Seepage rate per unit time: Q= K·i·A' (K: soil permeability coefficient, i: hydraulic gradient, A': area supported by the equipment). This is explained in detail in the soil mechanics professional specifications and will not be elaborated on here.

[0032] For the area A' borne by the equipment, if a 5,000 m2 building only uses one anti-floating and pressure relief device, then A' is 5,000 m2. If 10 anti-floating and pressure relief devices are evenly arranged, then A'≈500 m2. The actual area borne by each location varies depending on the location and needs to be confirmed based on actual conditions.

[0033] Non-flushing velocity v': The flow velocity at which sediment is not washed away is called the non-flushing velocity. For this anti-floating pressure relief technology, the non-flushing velocity is mainly related to the soil quality, or it can be said to be the characteristics of the soil. For example, silt and mud (particle size 0.005-0.05 mm) have a non-flushing velocity of 0.09-0.13 m / s; fine sand (particle size 0.05-0.25 mm) has a non-flushing velocity of 0.13-0.20 m / s; medium sand (particle size 0.25-1.0 mm) has a non-flushing velocity of 0.2-0.35 m / s; coarse sand (particle size 1.0-2.5 mm) has a non-flushing velocity of 0.35-0.40 m / s; medium gravel (particle size 5.0-10.0 mm) has a non-flushing velocity of 0.50-0.60 m / s (please refer to the "River Dynamics" and hydraulic calculation manual for detailed tables or calculations). Calculation of the initial value Smin of floating deformation pressure relief: Flow rate per unit time (Q) = equal to the non-flushing velocity (v') × area (A) Area (A) = floating deformation value S × perimeter of fragment layer 13 C Area (A) is the area where water flows through the intersection of the fragment layer 13 and the original soil in the water cake 8. The water flow rate through the original soil here is the fastest, and it is most likely to carry away the sediment of the original soil.

[0034] The above formula is particularly applicable to the case where the upper surface of the covering structure 5 is circular and the bracket 2 is located at the axis of the circle.

[0035] The edge of the covering structure of the displacement type anti-floating and pressure relief device, that is, the intersection with the original soil, is calculated according to the non-flushing flow velocity of the original soil to determine the initial value of the floating deformation and pressure relief. The selection of materials in the covering structure is determined according to the non-flushing flow velocity of the material, including the determination of the diameter of the stainless steel grid in the covering structure.

[0036] The calculation of the drainage pipe diameter is based on the required flow rate and the principle of smooth discharge. The "Water Supply and Drainage" design specifications have detailed formulas and explanations, so I will not go into details here.

[0037] When using this technology, it is recommended to increase the ductility of the building structure according to project requirements, so that during the building's buoyancy, the structural components will first fail through cracking, rather than concrete crushing. This is covered in the building structure design code and will not be detailed here.

[0038] Glossary: Smax, the floating deformation limit, is determined by utilising existing elastic-plastic finite element analysis software, inputting relevant building information into the software to analyse the development of cracks caused by the building's floating deformation. When cracks in structural components reach permitted values ​​(available in national standards), or when individual components (e.g., 5%) exceed permitted values, the building's floating deformation limit is determined. Repairs are generally unnecessary or can be performed with minimal repairs. This deformation limit is known as the non-destructive deformation limit of the structure and serves as the floating deformation limit. Factors influencing this include underground building area, length and width, column grid size, structural type, and materials. This value varies for different locations and is determined through design calculations. This is a complex process, typically performed using existing building structure calculation software and undertaken by the structural designer.

[0039] Initial floating deformation pressure relief value Smin: This term is a coined term proposed by the present invention. It represents the floating deformation value at the start of building floating pressure relief drainage. This ensures that the building's floating deformation does not exceed the floating deformation limit and provides early pressure relief and drainage. When the water flow velocity exceeds the non-flushing flow velocity during drainage, soil particles are carried away. To control the water flow velocity, an initial floating deformation pressure relief value is set. The initial floating deformation pressure relief value is determined based on the principle of preventing soil particles from being carried away. Key influencing factors include the selection of displacement-type anti-floating pressure relief devices (model and quantity), geological conditions, soil properties, and the design of the enveloping structure. This value varies for different locations and is determined by design calculations.

[0040] The working process of the present invention: Let's first briefly describe the process of anti-floating damage of underground buildings. When the groundwater level gradually rises, the water buoyancy increases. When the water buoyancy is greater than the weight of the building, the underground building floats and deforms, and the foundation (raft) 6 separates from the foundation soil to form a thin water cake 8. The upward displacement value is the same as the thickness of the water cake 8. As the amount of water increases, the volume of the water cake gradually increases, the thickness increases, and the floating deformation of the building increases. When the floating deformation of the building is within the elastic range, the building will not be damaged. When it exceeds the elastic deformation and gradually enters the elastic-plastic state, cracks appear in the building. The cracks range from small to large (the deformation reaches the floating deformation limit Smax, and then exceeds the floating deformation limit Smax), enters the plastic state, and gradually the building is destroyed.

[0041] During the destruction process, the speed at which the volume of the water cake 8 expands, or the speed at which the thickness of the water cake 8 increases, is related to factors such as the permeability coefficient of the foundation soil, the water head height, the foundation area, and so on. For a single project, the maximum expansion speed is determined. Before the building's floating deformation enters the elastic-plastic state, the water in the water cake 8 is drained so that the drainage speed is greater than its expansion speed, thereby ensuring the safety of the building. The size and number of the displacement-type anti-floating pressure relief device are determined based on factors such as the maximum expansion speed of the water cake 8. During the drainage process, the water in the water cake flows to the pressure relief device. The water flow velocity v is inversely proportional to the thickness of the water cake 8. Increasing the thickness can reduce the water flow velocity. When the water flow velocity v is too fast and exceeds the soil's non-flushing flow velocity v', soil particles are carried away. When it reaches a certain amount, it affects the safety of the later construction. Therefore, the water flow velocity must be controlled to be less than the soil's non-flushing flow velocity v'. The water flow velocity in the water cake 8 can be controlled by controlling the thickness of the water cake 8.

[0042] A design method for an anti-floating and pressure relief structure including the above-mentioned displacement-type anti-floating and pressure relief device, the method comprising: designing and determining the number and position of the displacement-type pressure relief device according to the underground building and geological conditions, respectively calculating the floating deformation limit of the building as Smax (effective measures may also be taken to increase the structural ductility and increase Smax), and the corresponding floating deformation pressure relief initial value Smin at each displacement-type pressure relief device, ensuring that Smin is less than Smax, and that the difference between Smax and Smin is a certain amount (sufficient for pressure relief and drainage), and when it is found that Smin is greater than Smax or the values ​​are close (for example, the difference is less than 20%) at a certain displacement-type anti-floating and pressure relief device, by increasing the value of the displacement-type anti-floating and pressure relief device, the displacement-type anti-floating and pressure relief device is increased. The density of the displacement type anti-floating and pressure relief device near the displacement type anti-floating and pressure relief device is reduced, the equipment burden area A' of the displacement type anti-floating and pressure relief device is reduced and / or the size of the area surrounded by the fragment layer 13 is increased to increase the perimeter C, so that Smin is reduced to Smin<Smax and the difference requirement is met, and the value of S is determined by Smin, so that S=Smin or S is greater than Smin value 0~5mm, and it is ensured that S is much smaller than Smax (for example, the difference is greater than 20%). According to the determined S value, during actual installation, the position of the adjusting nut 34 on the screw 33 is adjusted to change the maximum elongation of the spring 30, so that after the drain pipe 4 rises to a height S, it disengages from the spring top plate 31 and starts to drain.

[0043] The working process of the present invention is as follows: according to the underground building and geological conditions, the number and position of the displacement type pressure relief device are designed to ensure that the building's floating deformation value S does not exceed the floating deformation limit Smax. Figure 8 、 Figure 9 .1), the displacement type drainage switch 3 is not opened, and there is no water leakage. As the buoyancy of water increases, the building begins to slowly float and deform, forming a water cake 8 between the foundation (raft) 6 and the foundation soil, and the space enclosed by the stainless steel grid 14 of the covering structure 5 is filled with water. When the building's floating deformation is small, the displacement type drainage switch 3 is not opened (such as Figure 7 、 Figure 9 .2) When the building's upward deformation exceeds the initial value of the upward deformation pressure relief Smin and reaches the upward deformation amount S, the displacement type drainage switch is opened (such as Figure 1 、 Figure 9 3) Pressure relief and drainage begin. As the upward deformation S increases, the drainage outlet is opened wider, increasing the drainage volume until equilibrium is reached, ensuring that the building's upward deformation S does not exceed the upward deformation limit Smax. When the groundwater level drops, the water in the water cake 8 reverses its flow, and the building's upward deformation returns to zero.

[0044] The building surface ring 44 at the upper end of the sleeve 1, along with the blind flanges 41 and 42, and the internal threaded holes and nuts 43 on the blind flanges, are all designed for subsequent inspection, maintenance, and repair. During inspection, the concrete, mortar, or "manhole cover" within the ring 44 is removed, the nut 43 is unscrewed, and an inspection rod is inserted through the nut hole 43 to check for silt at the bottom. If so, the blind flange 42 is removed and the silt removed. Alternatively, if the displacement drain valve 3 has exceeded its service life, it can be removed, replaced, and then restored.

[0045] This pressure relief device adopts measures such as increasing the wall thickness of ordinary steel, applying chemical anti-corrosion, or using corrosion-resistant materials to solve the durability problem and ensure the service life. Other equivalent materials can also be used.

[0046] The sleeve 1 and the bracket 2 are not limited to circular shapes. The displacement type drain switch 3 is divided into two types: detachable and non-detachable. The non-detachable type can be selected only during the construction period. When it is non-detachable, the displacement type drain switch 3 and the bracket 2 are integrated into one, and the two can be further simplified.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the scope of protection of the present invention.

Claims

1. A displacement type anti-floating pressure relief device, characterized in that: The invention comprises a sleeve (1) fixed in a foundation (6) at the bottom of a building, the sleeve (1) having an opening at the bottom; and a bracket (2) fixed in a foundation soil layer below the foundation (6); a drainage pipe (4) is also fixed in the foundation (6), the outlet end of the drainage pipe (4) extends from the top of the foundation (6), the drainage end (40) of the drainage pipe (4) passes through and extends into the sleeve (1), the top of the bracket (2) is fixedly connected to a displacement type drainage switch (3), a spring (30) is provided at the top of the displacement type drainage switch (3), the maximum elongation of the spring (30) is adjustable, the top of the spring (30) is fixedly connected to a spring top plate (31), the spring top plate (31) corresponds to the drainage end (40) of the drainage pipe (4) up and down, and when the spring top plate (31) abuts against the water inlet end of the drainage pipe (4), the drainage end (40) of the drainage pipe (4) is blocked.

2. A displacement type anti-floating pressure relief device according to claim 1, characterized in that: The displacement type drain switch (3) comprises an upper support (22) and an elastic member detachably connected to the upper support (22); the upper support (22) comprises at least one vertical steel plate (23) fixedly connected to the bracket (2), the top of the vertical steel plate (23) being fixedly connected to the horizontal steel plate (25); the elastic member comprises a spring bottom plate (26) abutting the top of the horizontal steel plate (25), the top of the spring bottom plate (26) being fixedly connected to the bottom end of the spring (30), the top of the spring (30) being fixedly connected to the spring top plate (31), the top of the spring top plate (31) being fixedly connected to the anti-leakage gasket (32), the bottom of the spring top plate (31) being fixedly connected to the screw rod (33), the screw rod (33) passing downward through the spring bottom plate (26) and the horizontal steel plate (25) in sequence, and being threadedly connected to an adjusting nut (34), so that the maximum elongation of the spring (30) can be adjusted by adjusting the position of the nut (34) on the screw rod (33) and the limiting cooperation with the bottom of the horizontal steel plate (25).

3. A displacement type anti-floating pressure relief device according to claim 2, characterized in that: The upper support (22) and the elastic member are detachably connected in that: the horizontal steel plate (25) extends from the middle to the side through the horizontal opening groove (24), the screw (33) between the spring base plate (26) and the adjusting nut (34) is installed in the upper support (22) through the horizontal opening groove (24), the bottom of the spring base plate (26) is fixedly connected to at least one limiting steel ball (27), and the top of the horizontal steel plate (25) is provided with a hole (29) that cooperates with the limiting steel ball (27) for positioning.

4. A displacement type anti-floating pressure relief device according to claim 2, characterized in that: A covering structure (5) is provided in the foundation soil layer, the covering structure (5) covers the outside of the support (2), the covering structure (5) includes a fragment layer (13) connected to the foundation soil of the foundation soil layer, a permeable geotextile (12) is provided between the fragment layer (13) and the foundation soil for limiting, a stainless steel grid net (14) is provided in the fragment layer (13) for limiting, and the stainless steel grid net (14) is provided around the outside of the support (2).

5. A displacement type anti-floating pressure relief device according to claim 4, characterized in that: A reinforced concrete layer is provided at the bottom of the fragment layer (13), and the permeable geotextile (12) and the stainless steel grid (14) are fixedly connected to the reinforced concrete layer. The reinforced concrete layer includes a concrete slab (11) and a steel mesh (10) wrapped in the concrete slab (11). A plurality of water inlet holes are provided on the bracket (2), and a plurality of reserved steel holes (17) are provided at the bottom of the bracket (2). The bottom of the bracket (2) is pre-buried in the concrete slab (11), and the steel bars constituting the steel mesh (10) pass through the reserved steel holes (17).

6. A displacement type anti-floating pressure relief device according to claim 5, characterized in that: A circular ring (44) for the building surface layer is fixed on the foundation (6) at the top of the sleeve (1), the top of the sleeve (1) is fixedly connected to the flange (41), the top of the flange (41) is fixedly connected to the blind plate (42) by screws (43), and the outer periphery of the sleeve (1) is fixedly connected to the water-stop steel plate (39); a waterproof cushion layer (7) is fixed at the bottom of the foundation (6), and the waterproof cushion layer (7) is separated from the foundation soil layer when the building floats up. The bottom of the waterproof cushion layer (7) is fixedly connected to the cover plate (36) surrounding the sleeve (1), and two layers of studs (38) are fixed to the outer periphery of the bottom of the sleeve (1) along the circumferential array, and the cover plate (36) is clamped between the two layers of studs (38).

7. A displacement type anti-floating pressure relief device according to claim 6, characterized in that: The outer periphery of the bracket (2) is fixedly connected to the first pressure-resistant steel block (20), and the inner wall of the sleeve (1) is fixedly connected to the second pressure-resistant steel block (37). When the building is not floating, the first pressure-resistant steel block (20) and the second pressure-resistant steel block (37) are in contact.

8. A displacement type anti-floating pressure relief device according to claim 7, characterized in that: The floating deformation limit of the building is Smax; the height difference from the drainage end (40) when the building is not floating to the drainage end (40) when it separates from the spring top plate (31) and starts to drain is the floating pressure relief value S, and the initial floating deformation pressure relief value is Smin, Smin≤S<Smax, where Smin=(K•i•A') / (C•v'), where K is the soil permeability coefficient of the foundation soil layer, i is the hydraulic gradient, A' is the area borne by the equipment, C is the perimeter of the area enclosed by the junction of the fragment layer (13) and the foundation soil, and v' is the non-flushing flow velocity determined according to the soil quality of the foundation soil.

9. A design method for an anti-floating and pressure relief structure comprising a displacement-type anti-floating and pressure relief device according to any one of claims 1 to 8, characterized in that: The method is as follows: according to the underground building and geological conditions, the number and position of the displacement type pressure relief devices are designed and determined, the floating deformation limit of the building is calculated as Smax, and the corresponding floating deformation pressure relief initial value Smin at each displacement type pressure relief device is calculated, and Smin is guaranteed to be less than Smax. When Smin>Smax is found at a certain displacement type anti-floating pressure relief device, the density of the displacement type anti-floating pressure relief devices near the location is increased, the area A' borne by the equipment of the displacement type anti-floating pressure relief device is reduced, and / or the size of the area surrounded by the fragment layer (13) is increased to increase the perimeter C, so that Smin is reduced to Smin<Smax. The value of S is determined by Smin, so that S=Smin or S is greater than the value of Smin by 0~5mm, and S<Smax is guaranteed. According to the determined S value, during actual installation, the position of the adjusting nut (34) on the screw (33) is adjusted to change the maximum extension of the spring (30), so that after the drainage pipe (4) rises to a height S, it is separated from the spring top plate (31) and starts to drain.

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