Water permeable structure for bottom plate of water inlet pool of pump station

Abstract

The invention relates to the technical field of pool bottom plate structures, in particular to a permeable structure of a pump station water inlet pool bottom plate. The beam lattice is arranged at the bottom of the water inlet pool to form a framework frame lattice; the water-permeable filler comprises a water-permeable layer and a composite inverted filter layer; wherein the side, connected with a protected soil body, of the beam lattice is the inner side, and the permeable layer and the composite inverted filter layer are distributed in the framework lattice from outside to inside, so that the permeable layer and the composite inverted filter layer are rigidly restrained by the framework lattice. The framework sashes provide rigid constraint to ensure the integrity and geometric stability of the non-fine concrete layer, so that long-term close contact of an interface between the composite inverted filter layer and the permeable layer is ensured, and key risk points of local high-gradient scouring and direct loss of fine particles caused by deformation are eliminated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pool bottom plate structure, in particular to a pump station water inlet pool bottom plate water permeable structure. BACKGROUND

[0002] The traditional pump station water inlet pool bottom plate adopts a reinforced concrete closed structure, but:

[0003] During the maintenance period, the water in the pump station water inlet pool must be completely emptied for maintenance. The weight of the water body is the largest contributor to counteracting the uplift pressure. After emptying, this part of the huge downward load disappears instantaneously.

[0004] During the construction period, the structure self-weight is not fully formed, and the side wall, top plate and other structures on the bottom plate may not have been completed or the concrete strength may not have reached the design value, so the total structure self-weight is insufficient. At the same time, the pool is empty and there is no huge weight of the water body pressing downward. At this time, when the underground water level is high, the bottom plate will easily float up and crack due to the uplift pressure.

[0005] The existing technology is to drill holes for water permeability, but in a low hydraulic gradient environment, fine particles may flow away due to the failure of reverse filtration, causing permeation deformation and blockage. Moreover, the existing closed structure relies on increasing counterweight or anchor rod to resist floating, which is costly and complex to construct. SUMMARY

[0006] The purpose of the present application is to provide a pump station water inlet pool bottom plate water permeable structure, which solves the contradiction between the bottom plate floatation force destruction and the water permeable structure clogging under high underground water level. The bottom plate water permeable structure of the present application is actually realized by water permeable no-fines concrete. Since no-fines concrete does not fill the voids between coarse aggregates with sand, and the cement paste only plays a point connection role without filling these voids, a large number of, large-sized, interconnected voids (pores) are formed between the coarse aggregate particles, which is the water permeable layer.

[0007] The porosity of no-fines concrete is usually 25%-35% (ordinary concrete is usually less than 3%). These pores are not just isolated holes, but are interconnected through the openings between the contact points of coarse aggregates, forming a three-dimensional network channel throughout the concrete body, which provides sufficient space for water. At this time, if fine-grained soil enters the no-fines concrete pore structure with water flow, it will cause clogging. Once clogging occurs, the uplift pressure at the bottom of the bottom plate will be greater than the self-weight of the bottom plate, causing top support damage.

[0008] Therefore, the pump station water inlet pool bottom plate water permeable structure of the present application comprises:

[0009] A grillage is arranged at the bottom of the water inlet pool to form a skeleton frame.

[0010] and,

[0011] The water-permeable filler comprises a water-permeable layer and a composite anti-filtration layer.

[0012] The beam grillage is connected to the protected soil body on one side, and the water-permeable layer and the composite anti-filtration layer are distributed from outside to inside in the skeleton frame, so that the water-permeable layer and the composite anti-filtration layer are rigidly constrained by the skeleton frame.

[0013] Preferably, the water-permeable layer is sand-free concrete.

[0014] Preferably, the composite anti-filtration layer comprises four layers of anti-filtration layers laid from outside to inside.

[0015] The first layer is 1-5 mm graded gravel, the second layer is 5-20 mm graded gravel, the third layer is 20-40 mm graded gravel, and the fourth layer is 40-80 mm graded gravel, and the thickness of each layer is 300 mm.

[0016] The above arrangement can prevent the loss of >1 mm fine particles (internal erosion), and is particularly suitable for long-term stability under low hydraulic gradient, which can effectively prevent the loss of fine particles and ensure that the sand-free concrete is not clogged, ensuring the safety of the pump station intake pool. Specifically:

[0017] The composite anti-filtration layer is in close contact with the protected soil body (fine particle soil prone to loss). Its core function is to directly block most fine particles from passing through by relying on its relatively dense and uniform small pore size structure (carefully selected according to the particle size distribution d85 of the protected soil). The composite anti-filtration layer is provided with four layers from outside to inside, and the initial filter cake only allows a small amount of the finest particles to temporarily pass through or adhere to its surface, gradually forming a finer filter cake. This layer of filter cake itself becomes a more effective filter layer, further preventing the loss of subsequent fine particles, which is the key to preventing loss during the start-up period.

[0018] The sand-free concrete has high connectivity and large porosity, providing a smooth and low-resistance channel for the main permeable water flow, rapidly removing water, reducing internal pore water pressure and permeable hydraulic gradient. Moreover, the huge pore space of the sand-free concrete can temporarily accommodate a small amount of extremely fine particles that seep out from the first layer of geotextile (or particles that fall off during filter cake formation), preventing these particles from accumulating and clogging in narrow areas.

[0019] In addition, when water flows from the composite anti-filtration layer into the sand-free concrete, the cross-sectional area suddenly increases, the flow rate significantly decreases, and the water's ability to carry particles (scouring) (shear force) is greatly reduced. Not only that, but it also provides space and time for filter cake self-healing. Even if the composite anti-filtration layer is partially clogged or damaged, the reduced flow rate and accommodation capacity of the sand-free concrete provide an opportunity for the reformation or "self-healing" of the filter cake on the surface of the composite anti-filtration layer, preventing rapid expansion of the failure.

[0020] Therefore, the composite filter layer cooperates with the sandless concrete to effectively prevent the loss of fine particles (internal erosion) of >1mm, especially for long-term stability under low hydraulic gradient. The sandless concrete behind has a huge reserve drainage capacity. Even if the composite filter layer is partially blocked, causing its permeability to decrease, as long as the sandless concrete remains unblocked, the overall drainage capacity of the system decreases relatively slowly. Then, the unblocked drainage reduces the accumulation of pore water pressure, so that the seepage force (i) acting on the protected soil does not increase sharply to the critical value, thereby maintaining the seepability stability. The sandless concrete acts as an important "pressure relief valve".

[0021] Further, the beam grid includes a first partition beam and a second partition beam.

[0022] In the first technical solution, the first partition beam is a transverse partition beam, and the second partition beam is a longitudinal partition beam, and the transverse partition beam and the longitudinal partition beam are connected to form a skeleton frame grid.

[0023] In the second technical solution, the first partition beam and the second partition beam are applied to a slope, and the included angle between the first partition beam and the second partition beam is 45°, and the first partition beam and the second partition beam are connected to form a diamond skeleton frame grid.

[0024] In the third technical solution, the first partition beam is a ring beam, and the second partition beam is a radial beam, and the radial beam radiates outward from the center well, and the ring beam is concentrically arranged, and the innermost layer forms the center well.

[0025] The above technical solution solves the main filtering and drainage problems by combining the composite filter layer and the sandless concrete. The purpose of the beam grid structure design is:

[0026] The beam grid adopts a reinforced concrete structure, which is impermeable and has high structural strength, and plays a role of skeleton. The purpose of filling the sandless concrete inside is to serve as a permeable layer and play a role of drainage. The beam height is greater than or equal to 1700mm, and the main reason is that the thickness of the filled sandless concrete is 400mm, and 4 layers of filter layer with a thickness of 300mm are arranged below, and the total thickness is 300*4+400=1600mm. That is, the beam height of the beam grid should be greater than the sum of the thickness of the sandless concrete and the thickness of the filter layer to form rigid restraint.

[0027] That is, the beam grid itself is impermeable, and it does not directly participate in filtering fine particles or providing a main drainage channel. Its main role is reflected in the structural, restraining and partitioning properties, which provides important protection for the long-term stability and failure control of the entire permeable-filter system.

[0028] First, the skeleton frame can constrain the deformation of the sandless concrete (permeable layer) and maintain the close contact between the sandless concrete and the composite filter layer. The reason is that although the strength of the sandless concrete is ≥ 15 MPa, it is a porous and brittle material, and its bending and tensile resistance is much lower than that of ordinary concrete. Under the action of a large uneven load (such as equipment weight, soil pressure, and possible local settlement), temperature stress, or construction load, if there is no rigid constraint of the skeleton frame, the large-area sandless concrete layer may crack, warp, or locally crush and deform.

[0029] In addition, the staggered connection of the first and second partition beams forms an extremely solid and continuous rigid skeleton frame. This skeleton bears the main structural load and effectively transmits the upper structure (pump house, equipment, etc.) and possible backfill soil load to the foundation, greatly reducing the bending and shear stress of the sandless concrete layer and preventing it from cracking or crushing due to overloading.

[0030] In addition, the skeleton frame divides the large-area permeable layer into a plurality of relatively small blocks. The sandless concrete is tightly filled in these "lattices" and is constrained by the beams on all sides and the bottom (through the filter layer). This constraint significantly limits the lateral expansion, shrinkage, or warping deformation of the sandless concrete under load or temperature changes.

[0031] Maintaining close contact between the sandless concrete and the composite filter layer is essential to ensure smooth water flow without bypassing or local scouring, especially between the fine layer on the uppermost layer and the sandless concrete layer. If the sandless concrete layer deforms significantly (such as sinking, heaving, or cracking), it will disrupt this close contact and form gaps or concentrated flow channels at the interface. This can cause a dramatic increase in local hydraulic gradient, with water flow concentrated in the gaps or cracks, resulting in a much higher hydraulic gradient than designed. Under the impact of high gradient and high-speed water flow, the carefully designed gradation protection of the composite filter layer can be locally breached, and fine particles are more easily washed away.

[0032] Furthermore, zoning isolation can limit the scope of failure and improve system redundancy and maintainability:

[0033] Because even with the use of a composite filter layer and sandless concrete, there is still a possibility of local filter failure or permeable layer clogging in extreme conditions (such as abnormally high water head difference, construction defects, or long-term aging) or in local areas (such as edges and corner stress concentration points). In traditional large-area permeable structures, a single failure can lead to concentrated flow scouring, rapidly expanding the scope of failure, and even causing permeation damage to the entire bottom plate.

[0034] At this point, the interlaced first and second partition beams form physical barriers, dividing the entire base slab into many independent "cells." If the filter layer in a "cell" fails partially or the permeable layer becomes partially clogged, the water flow cannot easily cross the partition beams of adjacent "cells." This effectively confines seepage damage or clogging problems to a single or a few "cells," preventing them from spreading rapidly throughout the entire base slab like dominoes. This greatly improves the overall redundancy and robustness of the system.

[0035] Furthermore, when abnormal uplift pressure or poor drainage is detected in a certain area, the grid structure makes it very easy to locate the problematic unit. Maintenance personnel can precisely drill and unclog, perform localized grouting repairs, or replace the filling material within the problematic "grid" without damaging the entire base plate, thereby reducing maintenance and construction costs. Ensuring that localized problems do not escalate into catastrophic global damage, and providing time and space for inspection and maintenance, is a key design feature for guaranteeing long-term safe operation.

[0036] Finally, the beam grid, combined with the underlying foundation treatment, provides an extremely robust and flat reference surface for the entire base slab. This ensures uniform load distribution and minimizes uneven settlement and deformation. Indirectly, it provides a stable, low-stress working environment for the composite filter layer and no-fines concrete, which is beneficial for them to maintain their design functionality over the long term. Furthermore, the beam grid itself forms reliable anchorage, further ensuring the overall stability of the base slab while simplifying construction.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. In the permeable structure of the bottom slab of the pump station's intake pool, the skeleton frame provides rigid constraints, ensuring the integrity and geometric stability of the no-fines concrete layer. This guarantees long-term close contact between the composite filter layer and the permeable layer, eliminating the key risk points of local high-gradient scouring and direct loss of fine particles due to deformation.

[0039] 2. In the permeable structure of the bottom plate of the pump station's intake pool, the interlaced first and second partition beams form a series of physical barriers, which effectively restricts the problem of seepage damage or siltation to a single or a few "cells", greatly improving the overall redundancy and robustness of the system.

[0040] 3. In the permeable structure of the bottom slab of the pump station's intake pool, the beam grid itself forms a reliable anchorage, ensuring the overall stability of the bottom slab while making construction simpler. Attached Figure Description

[0041] Figure 1 This is a side view of the pump station inlet pool of the present invention;

[0042] Figure 2 This is a top view of the pump station intake pool of the present invention;

[0043] Figure 3 Schematic diagram of grillage structure of second embodiment of the present application;

[0044] Figure 4 Schematic diagram of grillage structure of third embodiment of the present application;

[0045] Figure 5 Schematic diagram of fine particle loss curve of experimental example of the present application;

[0046] Figure 6 Schematic diagram of permeability coefficient curve of experimental example of the present application.

[0047] The meanings of various reference numerals in the drawings are as follows:

[0048] 1, water inlet channel; 2, water inlet pool; 3, grillage; 31, first partition beam; 32, second partition beam; 4, water permeable layer; 5, composite anti-filtration layer; 6, water absorption pipe; 7, diversion wall; 8, retaining wall. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0050] The current water permeable structure is mainly threatened by the continuous and slow loss of fine particles (internal erosion) and the clogging of the anti-filtration layer in a low hydraulic gradient environment, and the traditional structure is difficult to effectively cope with these threats, for example:

[0051] Chinese patent publication No. CN203213095U discloses an anti-floating structure of underground water supply and drainage structure, the core idea of which is to form a composite drainage channel by combining sand and gravel anti-filtration cushion layer with horizontal filter pipe network and vertical water permeable holes in the bottom plate to reduce the uplift force. It can be seen that the focus is on the design of the drainage channel, but the design of the anti-filtration layer mainly relies on physical screening, and fine particles (especially <0.1mm silt and clay particles) can easily penetrate the interlayer gap slowly, causing continuous internal erosion. Once partially clogged (especially fine particles deposited under low gradient), the permeability will decrease sharply and it is difficult to self-heal, and the drainage capacity will rapidly decay.

[0052] Another Chinese patent, its publication number CN215053496U discloses a buried box-pump integrated anti-floating pump station, the core idea of which is to form a heavy composite bottom plate by filling impermeable concrete into the metal bottom plate combined with the skeleton frame steel structure, and anchor it to the foundation to resist floating by relying on the self-weight and anchoring force. However, the problem of stability reduction caused by the loss of fine particles under the seepage action of the foundation soil is ignored.

[0053] Referring to Figure 1 The present application provides a pump station water inlet pool bottom plate water permeable structure, which is arranged in the pool bottom of the water inlet pool 2, and specifically comprises a beam grid 3 and a water permeable filler. The beam grid 3 forms a skeleton frame in the pool bottom, and the water permeable filler is arranged in the skeleton frame. The beam grid 3 plays a role of a skeleton, although it does not directly filter water or provide a main water permeable channel.

[0054] As to how to achieve the above, the following embodiments are provided:

[0055] In the first embodiment, the foundation is first treated, and after excavation to the design elevation, the foundation soil (such as fine sand) is leveled and compacted, and the compaction degree is ≥93%. When soft soil layer is encountered, a 30cm thick sand gravel cushion (particle size ≤40mm) is replaced.

[0056] Then the construction of the bottom plate water permeable structure is carried out. First, the beam grid 3 is poured, referring to Figure 2 , a rectangular skeleton frame with a size of 2.5m×2.5m is positioned to form a first partition beam 31 and a second partition beam 32. In this embodiment, the first partition beam 31 is a transverse partition beam, and the second partition beam 32 is a longitudinal partition beam. Then HRB400 steel bars are bound and C30 concrete is poured.

[0057] Secondly, the water permeable filler is laid in the 2.5m×2.5m skeleton frame, referring to Figure 1 , the water permeable filler includes a water permeable layer 4 and a composite anti-filtration layer 5 distributed from outside to inside. Then the composite anti-filtration layer 5 is laid first, which is laid from outside to inside with four layers of anti-filtration layers, which are:

[0058] The first layer is 1-5mm graded gravel, the second layer is 5-20mm graded gravel, the third layer is 20-40mm graded gravel, and the fourth layer is 40-80mm graded gravel, and the thickness of each layer is 300mm.

[0059] When laying the composite anti-filtration layer 5, it is required to use a flat vibrator to vibrate and compact each layer after paving, and the permeability coefficient k is ≥1×10⁻²cm / s. The interface between the layers is manually raked to 10cm to avoid particle size separation and form seepage channels.

[0060] After the composite filter layer 5 is laid, the water-permeable layer 4 is laid on the composite filter layer 5, and the water-permeable layer 4 is cast in place with sand-free concrete, wherein the mix ratio is designed as follows:

[0061] Cement: P.O 42.5 grade, amounting to 280 kg / m³;

[0062] Coarse aggregate: single particle size 5-10 mm gravel (needle content ≤5%);

[0063] Water-cement ratio: 0.38;

[0064] Target porosity: 25%-35%.

[0065] The pouring process is as follows:

[0066] Laying geotextile (unit area mass ≥400 g / m²) on the surface of the composite filter layer 5;

[0067] Pouring sand-free concrete (thickness 400 mm);

[0068] Inserting a vibrating rod for compaction;

[0069] Covering and curing for ≥14 days after final setting to prevent water evaporation too quickly.

[0070] The water-permeable layer 4 is sand-free concrete with a porosity of 25%-35%, a thickness of 300-500 mm, and a compressive strength of ≥15 MPa. Its core value lies in effectively balancing the water permeability and the necessary structural bearing capacity. Sand-free concrete with a porosity of 25%-35% usually has a water permeability coefficient in the range of 0.5-3.0 mm / s or even higher. This means that in 1 second, water can penetrate 0.5-3 mm deep in the material. This is much higher than ordinary concrete (almost impermeable) and asphalt pavement (with very low water permeability coefficient).

[0071] A compressive strength of ≥15 MPa is a key indicator that ensures that this high-porosity material can still meet the bearing requirements under certain use conditions. Traditional concepts believe that high water permeability must lead to low strength. This strength indicator shows that modern mix ratio and process sand-free concrete successfully balances high water permeability and necessary structural strength. The strength standard: ≥15 MPa is a common minimum strength requirement for permeable concrete used in pedestrian walkways, bicycle paths, squares, and light parking lots (such as cars) (such as the relevant provisions in standards such as China CJJ / T 135 “Technical Specification for Permeable Cement Concrete Pavement”). Qualified mix ratio and construction can fully meet or even exceed this value (some can reach 20-30 MPa). A thickness of 300-500 mm further provides sufficient bearing thickness (usually used as a base or cushion). This thickness range combined with a strength of ≥15 MPa is sufficient to safely bear the load of pedestrians, bicycles, and even small vehicles, solving the practicality problem of permeable pavement.

[0072] Preferably, the height of the beam grid 3 is ≥1700mm, because the thickness of the filled sand-free concrete is 400mm, and there are 4 layers of reverse filter layer with a thickness of 300mm, so the total thickness is 300*4+400=1600mm, and the height should be greater than the sum of the thickness of the sand-free concrete and the thickness of the reverse filter layer to form rigid constraint.

[0073] Preferably, when pouring the beam grid 3, φ16@200mm anchor bars (exposed 200mm) are pre-embedded in the beam, which are used for subsequent fixation of the sand-free concrete.

[0074] In the second embodiment, the front pool part of the pump station water inlet pool 2 is a slope (gradient 1:4), and the stress direction of the bottom plate water permeable structure is inclined due to the impact of water flow. Therefore, the construction process of the beam grid 3 of this embodiment is:

[0075] Referring to Figure 3 , the formwork is positioned according to the 45° diagonal direction, and the first partition beam 31 and the second partition beam 32 are formed, the included angle between the first partition beam 31 and the second partition beam 32 is 45°, and the first partition beam 31 and the second partition beam 32 constitute a rhombus skeleton frame, and the diagonal line length of the skeleton frame is 2m; HRB400 steel bars are bound, and C30 concrete is poured.

[0076] In the third embodiment, the pump station water inlet pool 2 is circular, referring to Figure 4 , the construction process of the beam grid 3 of this embodiment is:

[0077] The beam grid 3 includes the first partition beam 31 and the second partition beam 32, the first partition beam 31 is a ring beam, and the second partition beam 32 is a radial beam, wherein: the radial beam radiates outward from the center well, the ring beam is concentrically arranged, and the innermost layer forms the center well; HRB400 steel bars are bound, and C30 concrete is poured.

[0078] When pouring, the central ring beam (center well) is poured first, then the radial beam, and finally the peripheral ring beam.

[0079] Taking the first embodiment as an example, referring to Figure 1 , the water inlet channel 1 is arranged on the upstream side of the water inlet pool 2, and the water suction pipe 6 of the pump station is arranged on the downstream side, referring to Figure 2 , the water suction pipe 6 is arranged as needed, and a plurality of water suction pipes 6 are arranged, and a guide wall 7 is arranged between adjacent two water suction pipes 6. In addition, the retaining wall 8 is arranged on both sides of the water inlet pool 2. The above structure is the conventional structure of the pump station, so it is not described here. However, it should be noted that the bottom plate water permeable structure of the present application is applicable to the pump station water inlet pool, which is not limited by the above structure.

[0080] The following discloses experimental examples for the first embodiment, which continuously erodes the two core indicators of fine particle loss (internal erosion) and permeability coefficient attenuation (influence of siltation) through low water gradient.

[0081] The experimental model is constructed, and the size of the experimental tank (equivalent to the water inlet pool 2) is 3m x 3m x 2m (length x width x height). The pump station bottom plate structure is simulated (according to a 1:10 scale):

[0082] The control group (prior art): single-layer filter layer (20-40mm gravel) and ordinary permeable concrete (no beam grid 3);

[0083] The experimental group (first embodiment): permeable layer 4, composite filter layer 5, and beam grid 3;

[0084] Test soil: fine sand (dso=0.15mm, non-uniformity coefficient Cu=3.5), simulating foundation soil;

[0085] Hydraulic gradient: constant i=0.02 (low gradient working condition, simulating long-term seepage);

[0086] Duration: 500 hours.

[0087] Monitoring indicators and methods, see the table below:

[0088] Monitoring indicators Measurement methods Frequency Fine particle loss Downstream sump filtration oven drying weighing Once every 24 hours Permeability coefficient k Upstream constant head, downstream flow measured Once every 12 hours Structural settlement Laser displacement sensor Continuous monitoring

[0089] See Figure 5 and Figure 6 , respectively showing the fine particle loss amount curve and the permeability coefficient curve, and combining the fine particle loss amount curve, the following conclusions are drawn:

[0090] The loss amount of the experimental group is always lower than that of the control group, and after 500 hours, the loss amount of the experimental group is only 32.5g / m², while that of the control group reaches 156g / m². The loss rate of the control group sharply rises after 200 hours (the filter layer gradation fails), and the experimental group maintains stability due to the fine interception of the composite filter layer 5.

[0091] Combining the permeability coefficient curve, the following conclusions are drawn:

[0092] The permeability coefficient of the control group decays to 52% of the initial value after 200 hours (due to fine particle clogging of pores); the experimental group maintains high permeability due to the drainage and pressure reduction of the permeable layer 4, and the retention rate is still 84% after 500 hours.

[0093] In addition, the rigidity of the beam grid 3 controls the settlement difference within 1mm / m, ensuring that the permeable layer 4 and the composite filter layer 5 are always in close contact.

[0094] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A permeable structure for the bottom slab of a pump station intake pool, characterized in that, include: The beam grid is set at the bottom of the inlet pool to form a skeleton grid; as well as, Permeable packing material, which includes a permeable layer and a composite filter layer; The side of the beam grid that connects to the protected soil is the inner side, and the permeable layer and composite filter layer are distributed from the outside to the inside within the skeleton grid so that the permeable layer and composite filter layer are rigidly constrained by the skeleton grid.

2. The permeable structure of the bottom slab of the pump station inlet pool according to claim 1, characterized in that, The rigid constraint is a constraint on the interfacial contact between the composite filter layer and the permeable layer.

3. The permeable structure of the bottom slab of the pump station intake pool according to claim 1, characterized in that, The rigid constraint is a constraint on the deformation of the permeable layer.

4. The permeable structure of the bottom slab of the pump station inlet pool according to claim 1, characterized in that, The permeable layer is made of no-fines concrete.

5. The permeable structure of the bottom slab of the pump station inlet pool according to claim 4, characterized in that, The porosity of the permeable layer is 25%-35%.

6. The permeable structure of the bottom slab of the pump station intake pool according to claim 1, characterized in that, The composite filter layer consists of four filter layers laid from the outside in, and the four filter layers are as follows: The first layer is 1-5mm graded crushed stone, the second layer is 5-20mm graded crushed stone, the third layer is 20-40mm graded crushed stone, and the fourth layer is 40-80mm graded crushed stone.

7. The permeable structure of the bottom slab of the pump station intake pool according to any one of claims 1-6, characterized in that, The beam grid includes a first partition beam and a second partition beam, which are connected in an alternating manner to form a skeleton frame.

8. The permeable structure of the bottom plate of the pump station inlet pool according to claim 7, characterized in that, The first partition beam is a horizontal partition beam, and the second grid beam is a longitudinal partition beam. The horizontal and longitudinal partition beams are connected to each other to form a rectangular skeleton grid.

9. The permeable structure of the bottom slab of the pump station inlet pool according to claim 7, characterized in that, The angle between the first partition beam and the second partition beam is 45°, and the first partition beam and the second partition beam are connected to form a rhomboid frame.

10. The permeable structure of the bottom slab of the pump station intake pool according to claim 7, characterized in that, The first partition beam is a circumferential beam, and the second partition beam is a radial beam; The radial beams radiate outward from the central well, and the circumferential beams are arranged concentrically, wherein the innermost circumferential beams form the central well.

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