Double-layer drainage system of large stilling pool

Abstract

The invention discloses a double-layer drainage system of a large stilling pool, and belongs to the technical field of water conservancy projects. The system comprises an upper-layer water collecting pipe network and a lower-layer water collecting pipe network which are arranged in a stilling pool apron parting seam. The upper-layer water collecting pipe network adopts soft permeable pipes with smaller diameters, is positioned in the middle of the apron and is used for collecting seepage water at the top of the apron; the lower-layer water collecting pipe network is composed of a concrete drainage ditch and embedded soft permeable pipes with large diameters, is located at the bottom of the apron and is used for collecting deep seepage caused by uplift pressure. The water flow of the two layers of pipe networks finally converges into the drainage gallery through the seamless steel pipe and is discharged by the water pump after being guided to the water-collecting well. Based on the design thought of distributed water collection, partitioned water catchment and multi-point drainage, the uplift pressure of the apron of the stilling pool is effectively reduced, the anti-floating stability of the apron bottom plate during flood discharge is remarkably improved, and the structure has the advantages of being high in drainage capacity, stable in operation and convenient to construct.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, specifically to a drainage system for stilling basins in large-scale water conservancy projects, particularly suitable for bottom flow stilling basins with large energy dissipation areas and high head differences between the upstream and downstream of water-retaining structures. Background Technology

[0002] In large-scale water conservancy projects, bottom flow energy dissipation is a commonly used and reliable energy dissipation method, especially suitable for projects with large-scale flood discharge, high discharge frequency, and navigation requirements. However, during flood discharge, the bottom plate of the bottom flow energy dissipation pool is subjected to enormous water flow impact and pulsating pressure. At the same time, due to the high head difference between upstream and downstream, a high uplift pressure is generated at the bottom of the pool. If the uplift pressure at the bottom of the apron is not effectively released, it will significantly increase the buoyancy force of the apron, which may exceed its anti-buoyancy stability safety factor, leading to the apron bottom plate being lifted, structural damage, and even serious accidents such as downstream river channel erosion.

[0003] The control of uplift pressure on the stilling basin apron primarily relies on its internal drainage system. Traditional drainage systems may suffer from insufficient drainage capacity, incomplete water collection, or susceptibility to clogging, making it difficult to meet the safe operation requirements of large stilling basins under high head and high flow conditions. Therefore, designing a drainage system with large drainage capacity, stable and reliable operation, and the ability to effectively reduce uplift pressure on the apron is a key technical issue in ensuring the safe operation of large stilling basins. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a double-layer drainage system for large stilling basins. This system can realize distributed water collection, zoned water collection, and multi-point drainage, thereby efficiently and reliably reducing the uplift pressure of the stilling basin apron and ensuring the anti-buoyancy stability of the apron bottom plate during flood discharge.

[0005] To address the problems existing in the background art, the present invention proposes a large-scale stilling basin double-layer drainage system, adopting the following technical solution:

[0006] A double-layer drainage system for a large stilling basin includes an upper water collection network and a lower water collection network installed in the joints of the stilling basin's retaining wall; both the upper and lower water collection networks are connected to a drainage gallery via seamless steel pipes; the bottom slope of the drainage gallery tends towards a water collection well, and a drainage pump is installed in the water collection well.

[0007] Furthermore, the upper water collection network adopts a flexible permeable pipe with a diameter of 10cm, and its centerline is 80cm away from the top surface of the stilling basin. The flexible permeable pipe is equipped with two water stops at the point where it passes through the stilling basin, namely a copper sheet water stop and a rubber water stop.

[0008] Furthermore, the lower-level water collection network includes a concrete drainage ditch poured at the bottom of the revetment, and a flexible permeable pipe with a diameter of 20cm buried in the concrete drainage ditch; the cross-section of the concrete drainage ditch is a right-angled trapezoid with a maximum height of 35cm, and it is poured with no-fines concrete; a non-woven fabric is tightly laid between the flexible permeable pipe and the no-fines concrete, and the two sides of the non-woven fabric are fixed to the rock foundation by 2mm thick, 3cm wide galvanized iron sheets and steel nails.

[0009] Furthermore, the flexible permeable pipe consists of four layers, including an inner lining support steel wire, an inner permeable layer, a middle filter layer, and an outer covering layer arranged sequentially from the inside out; the inner lining support steel wire is made of high-hardness spring steel wire, the inner permeable layer is made of PVC cylindrical skeleton, the middle filter layer is made of high-quality geotextile, and the outer covering layer is made of nylon yarn.

[0010] Furthermore, the seamless steel pipe has a diameter of 20cm; the flexible permeable pipe and the seamless steel pipe are connected by a socket joint, and the joint is filled with asphalt hemp.

[0011] Furthermore, the drainage corridor has a horseshoe-shaped cross-section with dimensions of 2.5m × 3.0m, and drainage ditches of 20cm × 20cm lie on both sides of the corridor. The bottom slope of the corridor is 0.1%.

[0012] Furthermore, depending on the different locations of the drainage corridors, the connection methods between the upper and lower water collection networks and the drainage corridors are adjusted accordingly:

[0013] When the drainage gallery is located inside the tail sill, the upper pipe network is split through a tee joint, one path drains along the surface of the tail sill, and the other path passes through the water stop and is introduced into the middle side wall of the gallery; the lower pipe network is connected to the gallery drainage ditch through seamless steel pipes.

[0014] When the drainage corridor is located inside the partition wall, the upper-level pipe network is directly introduced into the middle side wall of the corridor; the lower-level pipe network is connected to the corridor drainage ditch through seamless steel pipes.

[0015] When the drainage gallery is located inside the apron, the upper-level pipe network is divided through a tee joint: one path drains horizontally along the apron surface, while the other path passes through the waterstop and enters the middle side wall of the gallery; the lower-level pipe network is connected to the gallery's drainage ditch via seamless steel pipes.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention adopts a double-layer drainage design. The upper pipe network collects seepage water from the top of the apron, and the lower pipe network collects uplift pressure seepage from the bottom of the apron. This achieves effective control and collection of seepage water from different sources and at different depths, with a large drainage capacity and strong targeting.

[0018] 2. Based on the systematic design concept of "distributed water collection, zoned water collection, and multi-point drainage", the stilling basin apron is equipped with a network of pipes throughout the joints of the stilling basin, drainage corridors set in different zones, and multiple water collection wells, which ensures that there are no dead corners in the water collection and smooth drainage, greatly improving the uplift pressure reduction effect.

[0019] 3. The system structure is clear, and the components used (such as flexible permeable pipes, seamless steel pipes, and no-fines concrete) are mature and reliable. The construction process is well-defined, especially the construction methods of skip-pour casting and pre-embedded pipelines, which are conducive to ensuring construction quality and promoting the standardization of the design and construction of large stilling basin drainage systems. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the transverse and longitudinal cross-sections of the stilling basin double-layer drainage system of the present invention.

[0021] Figure 2 This is a schematic diagram of the construction of the flexible permeable pipe in this invention.

[0022] Figure 3 This is a detailed drawing of the concrete drainage ditch at the bottom of the revetment in this invention.

[0023] Figure 4 It is a cross-sectional view of the connection between the drainage pipe network and the drainage gallery located inside the tail sill.

[0024] Figure 5 It is a cross-sectional view of the connection between the drainage pipe network and the drainage corridor located inside the partition wall.

[0025] Figure 6 It is a cross-sectional view of the connection between the drainage pipe network and the drainage gallery located under the apron.

[0026] Figure 7 This is a detailed diagram of the connection between a flexible permeable pipe and a seamless steel pipe. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] like Figure 1 As shown, the core of the large stilling basin double-layer drainage system of the present invention lies in the installation of two independent water collection pipe networks within the joints (including transverse and longitudinal joints) of the stilling basin abutment. The upper water collection pipe network 1 is located in the middle of the abutment and is mainly used to collect water seeping into the abutment top surface gaps due to water weight and pulsating pressure. The lower water collection pipe network 2 is located at the bottom of the abutment, directly resting on the rock foundation, and is mainly used to collect deep seepage caused by high uplift pressure.

[0029] like Figure 2As shown, the flexible permeable pipe 10 used in this invention consists of four layers: the innermost layer is an inner lining support steel wire 11, which uses high-hardness spring steel wire to provide the pipe body with compressive strength; the outermost layer is an inner permeable layer 12, which uses a PVC cylindrical skeleton to form a water flow channel; the next outermost layer is a middle filter layer 13, which uses high-quality geotextile to prevent mud and sand from entering the pipe and causing blockage; the outermost layer is an outer covering layer 14, which uses nylon yarn to provide protection.

[0030] The upper-level water collection network 1 uses the aforementioned flexible permeable pipes with a diameter of 10cm, and its centerline is installed approximately 80cm from the top surface of the revetment. Two waterstops (not shown in the diagram) are installed where the permeable pipes pass through the revetment concrete: an upper copper sheet waterstop and a lower rubber waterstop to ensure effective sealing. The lower-level water collection network 2 uses flexible permeable pipes with a diameter of 20cm, and its installation method differs. For example... Figure 3 As shown, a concrete drainage ditch 20 with a right-angled trapezoidal cross-section was first excavated and poured on the rock foundation. The drainage ditch 20 was made of no-fines concrete, with a bottom height of 35cm, a top height of 20cm, and a width of 35cm. A flexible permeable pipe 21 with a diameter of 20cm was straightened and placed in the ditch. Then, non-woven fabric 22 was tightly laid on the permeable pipe 21. The two sides of the non-woven fabric 22 were covered with galvanized iron sheets 23 with a thickness of 2mm and a width of 3cm. The galvanized iron sheets 23 and the non-woven fabric 22 were then fixed to the rock foundation with steel nails 24. Finally, putty was applied around the galvanized iron sheets 23 for sealing. This structure can effectively collect deep seepage water and prevent clogging.

[0031] The water collected by the two-layer water collection network needs to flow into the main drainage system. For example... Figure 7 As shown, the flexible permeable pipe 10 and the seamless steel pipe 30 are connected by a socket joint, and the joint is sealed with asphalt-impregnated hemp 31. The other end of the seamless steel pipe 30 is connected to the drainage ditch of the drainage gallery 4. The drainage gallery 4 is usually arranged inside the tail sill, partition wall or under the revetment. Its cross-section is horseshoe-shaped (for example, 2.5m × 3.0m). There are 20cm × 20cm drainage ditches 41 on both sides. The bottom slope ratio of the gallery is 0.1%, and the water flows down the slope to the collection well 5.

[0032] Depending on the location of the corridor, the connection method needs to be adjusted accordingly:

[0033] The internal corridor of the tail sill (such as) Figure 4 (As shown): The upper pipe network 1 is divided by a T-junction installed inside the tail sill. One path forms a drainage channel along the surface of the tail sill, while the other path passes through the rubber waterstop and leads the water flow into the middle side wall of the corridor 4 and out. The lower pipe network 2 is directly connected to the corridor drainage ditch 41 through a seamless steel pipe 30.

[0034] Internal corridors within partition walls (such as) Figure 5(As shown): The upper-level pipe network 1 is directly introduced into the drainage corridor 4 inside the partition wall and flows out from its middle side wall. The lower-level pipe network 2 is connected to the corridor drainage ditch 41 through seamless steel pipe 30.

[0035] Internal corridors of the tank (such as) Figure 6 (As shown): The upper pipe network 1 is divided by a tee joint installed inside the apron. One path forms a horizontal drainage channel along the surface of the apron, while the other path passes through the rubber waterstop and leads the water flow into the middle side wall of the corridor 4 and out. The lower pipe network 2 is connected to the corridor drainage ditch 41 by seamless steel pipe 30.

[0036] Finally, the water flowing into drainage channel 4 flows down the slope into the nearest collection well 5 in each zone. The volume of collection well 5 must meet the requirement of storing seepage flow for a certain period of time (e.g., 6 hours). It is equipped with a pump room at the top, with a built-in drainage pump to pump the collected water back to the reservoir or discharge it to the downstream of the stilling basin, completing the entire drainage process.

[0037] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A double-layer drainage system for a large stilling basin, characterized in that, It includes an upper and lower water collection pipe network installed in the joints of the stilling basin revetment; both the upper and lower water collection pipe networks are connected to the drainage gallery through seamless steel pipes; the bottom slope of the drainage gallery tends towards the water collection well, and the water collection well is equipped with a drainage pump.

2. The large stilling basin double-layer drainage system according to claim 1, characterized in that, The upper water collection network adopts a first flexible permeable pipe, the center line of which is 70-90cm away from the top surface of the stilling basin. The first flexible permeable pipe is equipped with two water stops at the stilling basin, namely a copper sheet water stop and a rubber water stop.

3. The large stilling basin double-layer drainage system according to claim 2, characterized in that, The lower-level water collection network includes a concrete drainage ditch poured at the bottom of the revetment, and a second flexible permeable pipe buried in the concrete drainage ditch; the diameter of the second flexible permeable pipe is larger than the diameter of the first flexible permeable pipe.

4. The large stilling basin double-layer drainage system according to claim 3, characterized in that, The concrete drainage ditch has a right-angled trapezoidal cross-section and is poured with no-fines concrete; a non-woven fabric is laid between the second flexible permeable pipe and the no-fines concrete, and the two sides of the non-woven fabric are fixed to the rock foundation by galvanized iron sheets and steel nails.

5. The large stilling basin double-layer drainage system according to claim 2 or 3, characterized in that, The first flexible permeable pipe and / or the second flexible permeable pipe include, from the inside out, an inner lining support steel wire, an inner permeable layer, a middle filter layer and an outer covering layer.

6. The large stilling basin double-layer drainage system according to claim 5, characterized in that, The inner lining support steel wire is a high-hardness spring-hardened steel wire, the inner permeable layer is a PVC cylindrical skeleton, the middle filter layer is geotextile, and the outer covering layer is nylon yarn.

7. The large stilling basin double-layer drainage system according to claim 1, characterized in that, The diameter of the seamless steel pipe is 18-22cm; the flexible permeable pipe and the seamless steel pipe are connected by a socket joint, and the joint is filled with asphalt hemp.

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