Earth-rock dam geomembrane-clay core combined seepage prevention system and sealing method thereof

Abstract

The present application relates to a kind of earth-rock dam geomembrane-clay core wall combined seepage prevention system and its sealing method, including clay core wall, upstream seepage prevention wall, downstream seepage prevention wall, bank slope concrete, upstream geomembrane, dam bottom geomembrane, geomembrane anchoring zone, horizontal geomembrane;Bank slope concrete is provided with bank slope anchoring line;Upstream geomembrane covers the upstream face of clay core wall;Upstream geomembrane leaves upstream geomembrane side and is anchored along bank slope anchoring line and bank slope concrete anchoring connection;The both ends of dam bottom geomembrane are extended and provided with dam bottom geomembrane side edge;The upper portion of geomembrane anchoring zone is anchored with corresponding bank slope concrete, and the lower portion of geomembrane anchoring zone and dam bottom geomembrane side edge are anchored with bank slope concrete.The present application adopts geomembrane-clay core wall combined design, realizes upstream geomembrane side edge and dam bottom geomembrane side edge respectively adapt corresponding difference deformation by geomembrane anchoring zone and do not affect each other, while combining the flexible characteristics of clay core wall, form multiple collaborative seepage prevention structure, improve deformation adaptability and seepage prevention reliability.

Description

Technical Field

[0001] This invention relates to a geomembrane-clay core wall combined seepage prevention system for earth-rock dams and its sealing method, belonging to the field of water conservancy and hydropower engineering. Background Technology

[0002] With the deepening development and utilization of hydropower resources in western my country, dam sites with excellent geological conditions are becoming increasingly scarce, and many dams need to be built on foundations with deep overburden layers. For deep overburden foundations, earth-rock dams are the most commonly used dam type. However, due to the complex geological conditions of the overburden layer, earth-rock dams are prone to problems such as large settlement and deformation of the dam foundation and poor seepage stability. In traditional geomembrane anchoring schemes, the upstream geomembrane side is usually connected and anchored to the bottom geomembrane side to form a closed seepage prevention system. However, the upstream face of the dam body will undergo horizontal deformation under the action of water pressure, and the dam body will experience vertical settlement at the foundation due to its own weight. This means that the connection and anchoring parts of the upstream geomembrane side and the bottom geomembrane side need to withstand both horizontal and vertical deformation. However, the upstream geomembrane side and the bottom geomembrane side cannot adapt to the corresponding differential deformation, which can easily lead to the geomembrane tearing or detachment, causing leakage risks.

[0003] A search revealed that patent application number 202310828983.7 and publication number CN116641406A discloses a construction process for a single anti-seepage wall with geomembrane adhering to it. This involves first filling the underwater portion of the cofferdam with fill material, then compacting the fill material on both sides of the anti-seepage wall's grooves with vibration, and finally constructing the anti-seepage wall. Patent number 202111438899.1 and authorization announcement number CN114293512B discloses a composite geomembrane anti-seepage layer structure and construction method on a dam slope. This involves laying construction sand, a self-made geomembrane, a cushion layer, and a protective layer sequentially from bottom to top. The self-made geomembrane uses a self-made non-woven fabric-self-made waterproof membrane-self-made non-woven fabric sandwich structure. However, the above technical solutions do not specifically address the geomembrane arrangement for clay core walls. In terms of seepage prevention methods, invention patent No. 201510668585.9 and authorization announcement No. CN105297683B discloses a geomembrane core wall rockfill dam and its construction method; invention patent No. 201310351351.2 and authorization announcement No. CN103410123B discloses a water-retaining dam for water conservancy and hydropower projects. This type of technical solution arranges the geomembrane on the axis of the rockfill dam to replace the core wall for seepage prevention; invention patent No. 202010802936.1 and authorization announcement No. CN111910586B discloses a double-layer geomembrane core wall rockfill dam structure and construction method, in which water-retaining bodies are set on both sides of the core wall on the seepage prevention wall construction platform, and water-retaining bodies are placed on the water-retaining bodies. The above-mentioned seepage prevention technologies all involve extending the geomembrane layer by layer in a zigzag pattern to the top of the dam during the dam construction process. This vertical construction method may damage the geomembrane and affect the seepage prevention capacity of the earth-rock dam. At the same time, the dam body will undergo horizontal displacement under water pressure and vertical settlement due to gravity. According to the previous geomembrane layout scheme, the geomembrane is very easy to deform and break. In addition, the above-mentioned patents do not provide a complete seepage prevention structure. After long-term operation, there may be significant leakage, and the seepage prevention quality of the earth-rock dam cannot be guaranteed.

[0004] In summary, the existing technologies represented by the above-mentioned technical solutions cannot effectively address the issues of seepage prevention in the core wall of earth-rock dams and the differential deformation of the geomembrane at the corners of the core wall. There is an urgent need to develop a seepage prevention technology that can solve the above-mentioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to overcome the problems existing in the prior art and propose a geomembrane-clay core wall combined seepage prevention system and its sealing method for earth-rock dams. This system can enhance the overall seepage prevention capacity of the earth-rock dam and the ability of the geomembrane to adapt to different settlement deformations, while also reducing the construction difficulty of the earth-rock dam seepage prevention system.

[0006] The technical solution of this invention to solve its technical problem is as follows:

[0007] A geomembrane-clay core wall combined seepage control system for earth-rock dams includes a core wall, characterized in that it further includes an upstream seepage control wall, a downstream seepage control wall, bank slope concrete, an upstream geomembrane, a dam bottom geomembrane, geomembrane anchoring strips, and a horizontal geomembrane; the core wall is a clay core wall; the upstream and downstream seepage control walls are respectively fixed at the bottom of the clay core wall; the bank slope concrete is located at both ends of the clay core wall and is respectively provided with bank slope anchoring lines; the upstream geomembrane is laid from the corner between the upstream and bottom surfaces of the clay core wall, upwards along the upstream surface of the clay core wall, until it covers the entire upstream surface of the clay core wall; the upstream geomembrane has upstream geomembrane side edges at both ends of the clay core wall; the upstream geomembrane side edges are anchored to the bank slope concrete along the corresponding bank slope anchoring lines. The dam bottom geomembrane is located at the bottom of the clay core wall and between the upstream geomembrane and the upstream cutoff wall; the dam bottom geomembrane is anchored to the upstream cutoff wall; both ends of the dam bottom geomembrane are close to the bank slope concrete and extend downwards to form dam bottom geomembrane sides; geomembrane anchoring strips are located between the corresponding dam bottom geomembrane sides and the bank slope concrete; the upper part of the geomembrane anchoring strip is anchored to the corresponding bank slope concrete, and the lower part of the geomembrane anchoring strip and the corresponding dam bottom geomembrane sides are together anchored to the corresponding bank slope concrete; the horizontal geomembrane is located at the bottom of the clay core wall and between the upstream and downstream cutoff walls; the horizontal geomembrane is anchored to both the upstream and downstream cutoff walls.

[0008] This structure achieves self-adaptive and independent deformation of the upstream geomembrane side and the dam bottom geomembrane side by setting independent geomembrane anchoring strips, without affecting each other. At the same time, combined with the flexible characteristics of the clay core wall, it forms a multi-layered synergistic seepage prevention structure, which improves deformation adaptability and seepage prevention reliability.

[0009] The further improved technical solution of this invention is as follows:

[0010] Preferably, the cross-section of the clay core wall parallel to the water flow direction is trapezoidal; the upstream face of the clay core wall is an inverted trapezoid.

[0011] Preferably, the upstream and downstream cutoff walls are buried in the foundation of the earth-rock dam; the upstream and downstream cutoff walls are parallel to each other, with the upstream cutoff wall facing upstream of the earth-rock dam and the downstream cutoff wall facing downstream of the earth-rock dam.

[0012] Preferably, the projection of the bank slope anchoring line onto the cross section of the clay core wall parallel to the direction of water flow is a straight line parallel to the upstream surface of the clay core wall, and the distance between the projected straight line and the upstream surface of the clay core wall is 0.13% ± 0.05% of the length of the lower base of the trapezoid on the upstream surface of the clay core wall.

[0013] Preferably, the dimensions of the upstream geomembrane side are 0.13% ± 0.05% of the length of the lower base of the trapezoid on the upstream surface of the clay core wall, and are not less than the distance between the projected straight line of the bank slope anchoring line and the upstream surface of the clay core wall; the dimensions of the dam bottom geomembrane side are 0.13% ± 0.05% of the length of the lower base of the trapezoid on the upstream surface of the clay core wall; the upstream geomembrane is composed of two layers of geotextile sandwiching one layer of geomembrane material; the geomembrane anchoring strip is a rectangular PVC geomembrane with a thickness of 2-3.5 mm.

[0014] Preferably, the geomembrane at the bottom of the dam is laid horizontally from the corner between the upstream surface and the bottom of the clay core wall, along the bottom of the clay core wall to the top of the upstream seepage barrier wall; the horizontal geomembrane is laid horizontally from the top of the upstream seepage barrier wall, along the bottom of the clay core wall to the top of the downstream seepage barrier wall.

[0015] Preferably, the geomembrane at the bottom of the dam is anchored to the upstream cutoff wall, and the horizontal geomembrane is anchored to both the upstream and downstream cutoff walls, using double-row bolts arranged in two rows. Each lower row of bolts forms a lower anchorage area, and each upper row of bolts forms an upper anchorage area. The geomembrane at the bottom of the dam and the horizontal geomembrane are laid from the upper anchorage area to the lower anchorage area at the double-row bolt anchorage points. Then, the geomembrane at the bottom of the dam and the horizontal geomembrane are wrapped and sealed from the lower anchorage area to the upper anchorage area, forming a sealed area filled with flexible material. Finally, the ends of the geomembrane at the bottom of the dam and the horizontal geomembrane are welded to their respective locations on the top surface of the upstream or downstream cutoff wall.

[0016] Preferably, the geomembrane anchoring strip is anchored to the contact area of ​​the upstream geomembrane side; at the corner between the upstream surface and the bottom of the clay core wall, the overlapping areas of the upstream geomembrane, the dam bottom geomembrane, the upstream geomembrane side, the dam bottom geomembrane side and the geomembrane anchoring strip are partially covered and sealed by welding with an additional geomembrane.

[0017] By adopting the above preferred solutions, the specific technical details can be further optimized to achieve better technical results.

[0018] This invention also provides:

[0019] A sealing method for the geomembrane-clay core combined seepage prevention system of an earth-rock dam, as described above, is characterized by comprising the following steps:

[0020] Step 1: Install upstream and downstream cutoff walls at predetermined locations on the foundation of the earth-rock dam; lay a horizontal geomembrane between the upstream and downstream cutoff walls for vertical seepage prevention, and anchor the horizontal geomembrane to the top of the upstream and downstream cutoff walls respectively; lay the dam bottom geomembrane horizontally from the corner between the upstream and bottom surfaces of the clay core wall, along the bottom of the clay core wall to the top of the upstream cutoff wall, and anchor the dam bottom geomembrane to the top of the upstream cutoff wall; reserve the side edge of the dam bottom geomembrane.

[0021] The second step involves anchoring the upper part of the geomembrane anchoring strip to the corresponding slope concrete at the pre-defined location on the slope concrete. Then, the side of the dam bottom geomembrane is extended downwards, with the lower part of the corresponding geomembrane anchoring strip positioned between the side of the dam bottom geomembrane and the slope concrete. The lower part of the corresponding geomembrane anchoring strip and the side of the dam bottom geomembrane are then anchored together to the slope concrete. At the corner between the upstream and bottom surfaces of the clay core wall, additional geomembrane is used to partially cover and seal the overlapping areas of the upstream geomembrane, the dam bottom geomembrane, the side of the upstream geomembrane, the side of the dam bottom geomembrane, and the geomembrane anchoring strip using welding.

[0022] The third step is to pre-set the bank slope anchor lines on the concrete bank slopes at both ends of the clay core wall, and make the projection of the bank slope anchor lines on the cross section of the clay core wall parallel to the direction of water flow a straight line parallel to the upstream surface of the clay core wall.

[0023] Step 4: Construct a clay core wall at the predetermined location by compacting clay layer by layer; after each layer of clay is compacted, first lay the upstream geomembrane on the upstream surface of the clay core wall of that layer, and then anchor the sides of the upstream geomembrane at both ends of the clay core wall to the corresponding slope concrete along the slope anchoring line, and then continue to construct the next layer.

[0024] Step 5: After the clay core wall is built, its cross-section parallel to the water flow direction is trapezoidal, and its upstream face is an inverted trapezoid; construction is complete.

[0025] This sealing method enables reliable connection and anchoring of each structural unit to form a closed system, thereby achieving the combined seepage prevention effect of geomembrane-clay core wall. The use of geomembrane anchoring strips allows the geomembrane to adapt to the vertical settlement deformation of the dam at the bottom of the concrete bank slope and to adapt to downstream deformation at the junction of the core wall and the bank slope, avoiding local tensile damage to the geomembrane.

[0026] The further improved technical solution of this invention is as follows:

[0027] Preferably, the first step further includes: anchoring the geomembrane at the bottom of the dam to the upstream cutoff wall; anchoring the horizontal geomembrane to both the upstream and downstream cutoff walls using double-row bolts, arranged in two rows; forming a lower anchorage area at each lower row bolt anchorage point and an upper anchorage area at each upper row bolt anchorage point; laying the geomembrane at the bottom of the dam and the horizontal geomembrane from the upper anchorage area to the lower anchorage area at the double-row bolt anchorage points; then covering and sealing the geomembrane at the bottom of the dam and the horizontal geomembrane from the lower side of the lower anchorage area to the upper side of the upper anchorage area to form a sealed area, which is filled with flexible material; finally, welding the ends of the geomembrane at the bottom of the dam and the horizontal geomembrane to their respective locations on the top surface of the upstream or downstream cutoff wall.

[0028] The second step also includes: anchoring the geomembrane anchoring strip to the contact area on the side of the upstream geomembrane.

[0029] By adopting the above preferred solutions, the specific technical details of the sealing method can be further optimized to achieve better technical results.

[0030] Compared with existing technologies, this invention, by setting independent geomembrane anchoring strips, enables the geomembrane sides at the dam bottom extending from the top anchoring point of the upstream seepage barrier concrete and those extending from the upstream surface of the clay core wall to adapt to their respective differential deformations without affecting each other. It provides a complete slope anchoring line and an effective connection method between each part and the geomembrane anchoring strip. By arranging geomembrane anchoring strips and designing slope anchoring lines, a semi-enclosed connection anchoring structure is effectively formed, greatly improving the seepage prevention performance of the dam body, including enhanced compaction, improved waterproofing design, and reduced stress concentration, thereby maximizing the seepage prevention capacity of the core wall and improving the stability of the dam body, especially suitable for seepage prevention of the core wall of earth-rock dams. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the earth-rock dam with geomembrane-clay core wall combined seepage prevention according to Embodiment 1 of the present invention.

[0032] Figure 2 This is a schematic diagram from the upstream perspective of the geomembrane-clay core wall combined seepage prevention structure of Embodiment 1 of the present invention (the clay core wall is not shown in the figure).

[0033] Figure 3 This is a downstream view of the geomembrane-clay core wall combined seepage prevention structure of Embodiment 1 of the present invention (the clay core wall is not shown in the figure).

[0034] Figure 4 for Figure 3 A schematic diagram of the downstream view from the right bank.

[0035] Figure 5This is a schematic diagram of the arrangement of the geomembrane connection and anchoring structure at the top of the concrete anti-seepage wall in Embodiment 1 of the present invention.

[0036] Figure 6 for Figure 5 A detailed design diagram of the geomembrane anchoring structure at the top of the seepage-proof wall within the circle.

[0037] Figure 7 This is a schematic diagram of the geomembrane anchoring connection structure at the bottom of the bank slope in Embodiment 1 of the present invention.

[0038] Figure 8 This is a schematic diagram of the connection and anchoring between the bottom anchorage band of the bank slope and the concrete surface of the bank slope in Embodiment 1 of the present invention.

[0039] Figure 9 This is a schematic diagram of the anchoring line arrangement of the concrete geomembrane on the bank slope in Embodiment 1 of the present invention.

[0040] Figure 10 This is a schematic diagram of the vertical cross-section of the bank slope concrete along the anchorage line in Embodiment 1 of the present invention.

[0041] Figure 11 This is a schematic diagram of the horizontal cross-section of the concrete geomembrane anchoring structure on the bank slope in Embodiment 1 of the present invention. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the embodiments. However, the present invention is not limited to the examples given.

[0043] Example 1

[0044] This embodiment describes a specific implementation of a geomembrane-clay core wall combined seepage prevention system for earth-rock dams and its sealing method.

[0045] like Figures 1 to 11 As shown, the geomembrane-clay core wall combined seepage prevention system of the earth-rock dam in this embodiment includes a clay core wall 5, an upstream seepage prevention wall 2, a downstream seepage prevention wall 3, a bank slope concrete 7, an upstream geomembrane 1, a dam bottom geomembrane 1B, a geomembrane anchoring strip 8, and a horizontal geomembrane 4.

[0046] The clay core wall 5 is formed by compacting clay layer by layer, and its cross-section parallel to the water flow direction is trapezoidal. In this embodiment, the trapezoidal cross-section of the clay core wall 5 is 55m high, with an upper base length of 4m and a lower base length of 32m.

[0047] The upstream face of the clay core wall 5 is an inverted trapezoid. In this embodiment, the top of the upstream face of the clay core wall 5 is 360m long and the bottom is 190m long.

[0048] The upstream cutoff wall 2 and the downstream cutoff wall 3 are fixed at the bottom of the clay core wall 5 and buried in the foundation 9 of the earth-rock dam; the upstream cutoff wall 2 and the downstream cutoff wall 3 are parallel to each other, with the upstream cutoff wall 2 facing the upstream of the earth-rock dam and the downstream cutoff wall 3 facing the downstream of the earth-rock dam.

[0049] The concrete bank slope 7 is located at both ends of the clay core wall 5, and is provided with bank slope anchor lines 6 respectively. The projection of the bank slope anchor line 6 on the cross section of the clay core wall 5 parallel to the direction of water flow is a straight line parallel to the upstream surface of the clay core wall 5. In this embodiment, the distance between the straight line and the upstream surface of the clay core wall 5 is 25cm, which accounts for about 0.13% of the length of the lower base of the trapezoid on the upstream surface of the clay core wall 5.

[0050] The upstream geomembrane 1 is laid upwards from the corner between the upstream face and the bottom of the clay core wall 5, along the upstream face of the clay core wall 5, until it covers the entire upstream face of the clay core wall 5; the upstream geomembrane 1 has upstream geomembrane side edges 1A at both ends of the clay core wall 5; the upstream geomembrane side edges 1A are anchored to the corresponding slope concrete 7 along the slope anchoring line 6. In this embodiment, the upstream geomembrane 1 is composed of two layers of geotextile sandwiching one layer of geomembrane material; the reserved size of the upstream geomembrane side edge 1A is approximately 0.13% ± 0.05% of the length of the trapezoidal lower base of the upstream face of the clay core wall 5, and not less than 25cm (this value is the distance between the projected straight line of the slope anchoring line 6 mentioned above and the upstream face of the clay core wall 5).

[0051] The dam bottom geomembrane 1B is located at the bottom of the clay core wall 5, and between the upstream geomembrane 1 and the upstream cutoff wall 2. The dam bottom geomembrane 1B is laid horizontally from the corner between the upstream face and the bottom of the clay core wall 5, along the bottom of the clay core wall 5 to the top of the upstream cutoff wall 2. The dam bottom geomembrane 1B is anchored to the upstream cutoff wall 2. In this embodiment, the length and width of the dam bottom geomembrane 1B are 190m and 10m, respectively.

[0052] Both ends of the geomembrane 1B at the bottom of the dam are close to the concrete bank 7, and extend downwards to form geomembrane sidewalls 1C. Geomembrane anchoring strips 8 are located between the geomembrane sidewalls 1C and the concrete bank 7. The upper part of the geomembrane anchoring strip 8 is anchored to the corresponding concrete bank 7, and the lower part of the geomembrane anchoring strip 8, together with the corresponding geomembrane sidewalls 1C, is anchored to the corresponding concrete bank 7 (e.g., ...). Figure 8 (As shown). In this embodiment, the geomembrane anchoring strip 8 is a rectangular 3mm thick PVC geomembrane with a length and width of 10m and 1m respectively; the reserved dimension of the side 1C of the geomembrane at the bottom of the dam is approximately 0.13% ± 0.05% of the length of the trapezoidal lower base of the upstream face of the clay core wall 5, and not less than 25cm.

[0053] The horizontal geomembrane 4 is located at the bottom of the clay core wall 5, between the upstream cutoff wall 2 and the downstream cutoff wall 3. The horizontal geomembrane 4 is laid horizontally from the top of the upstream cutoff wall 2, along the bottom of the clay core wall 5, to the top of the downstream cutoff wall 3. The horizontal geomembrane 4 is anchored to both the upstream cutoff wall 2 and the downstream cutoff wall 3. In this embodiment, the length and width of the horizontal geomembrane 4 are 190m and 9.2m respectively, with an additional 75±15cm reserved in width for anchoring. The vertical centerline distance between the upstream cutoff wall 2 and the downstream cutoff wall 3 is 10m, and the thickness of both the upstream cutoff wall 2 and the downstream cutoff wall 3 is 0.8m.

[0054] like Figure 5 , Figure 6 As shown, the geomembrane 1B at the bottom of the dam has an additional 75±15cm reserved in width for connection and anchoring, and is anchored to the upstream cutoff wall 2. The horizontal geomembrane 4 is anchored to the upstream cutoff wall 2 and the downstream cutoff wall 3 respectively, and is anchored by double rows of bolts 10 (in this embodiment, the bolts 10 are arranged in two rows, and the distance between the center axes of the two rows of bolts 10 is 25cm). In this design, each lower row of bolts forms a lower anchorage area 11, and each upper row of bolts forms an upper anchorage area 12. The geomembrane 1B at the dam bottom and the horizontal geomembrane 4 are laid from the upper anchorage area 12 to the lower anchorage area 11 at the double-row bolt anchorage points. Then, the geomembrane 1B and the horizontal geomembrane 4 are respectively wrapped and sealed from the lower anchorage area 11 to the upper anchorage area 12, forming a sealed area filled with flexible material 13. Finally, the ends of the geomembrane 1B and the horizontal geomembrane 4 are welded to their respective locations on the top surface of the upstream or downstream cutoff wall 3. This wrapping and sealing, along with the filling with flexible material, significantly increases the effective anchorage duration and prevents moisture corrosion of the bolts.

[0055] In addition, the geomembrane anchoring strip 8 is anchored to the contact area of ​​the upstream geomembrane side 1A. At the same time, at the corner between the upstream face and the bottom of the clay core wall 5, the overlapping areas of the upstream geomembrane 1, the dam bottom geomembrane 1B, the upstream geomembrane side 1A, the dam bottom geomembrane side 1C and the geomembrane anchoring strip 8 are partially covered and sealed by welding with additional geomembrane.

[0056] The sealing method in this embodiment is as follows:

[0057] Step 1: Install upstream cutoff wall 2 and downstream cutoff wall 3 at predetermined locations on the foundation 9 of the earth-rock dam. Lay a horizontal geomembrane 4 between the upstream cutoff wall 2 and the downstream cutoff wall 3 for vertical seepage prevention, and anchor the horizontal geomembrane 4 to the top of the upstream cutoff wall 2 and the top of the downstream cutoff wall 3 respectively. The length and width of the horizontal geomembrane 4 are 190m and 9.2m respectively, and the vertical centerline distance between the upstream cutoff wall 2 and the downstream cutoff wall 3 is 10m. Lay the bottom geomembrane 1B horizontally from the corner between the upstream face and the bottom of the clay core wall 5, along the bottom of the clay core wall 5 to the top of the upstream cutoff wall 2, and anchor the bottom geomembrane 1B to the top of the upstream cutoff wall 2. Reserve a side edge 1C for the bottom geomembrane. The reserved dimension of the bottom geomembrane side edge 1C is approximately 0.13% ± 0.05% of the length of the trapezoidal bottom base of the upstream face of the clay core wall 5, and not less than 25cm. In this design, the anchoring connection is secured using double-row bolts 10, arranged in two rows with a 25cm center-to-center distance between the two rows. The geomembrane 1B at the dam bottom and the horizontal geomembrane 4 are laid from the upper anchoring area 12 to the lower anchoring area 11 at the double-row bolt anchoring points. Then, the geomembrane 1B and the horizontal geomembrane 4 are respectively wrapped and sealed from the lower anchoring area 11 to the upper anchoring area 12, forming a sealed area filled with flexible material 13. Finally, the ends of the geomembrane 1B and the horizontal geomembrane 4 are welded to their respective locations on the top surface of the upstream or downstream anti-seepage wall 2 or 3. This wrapping and sealing process, combined with the flexible material filling, extends the effective service life of the anchoring structure and prevents water corrosion of the bolts and damage to the anchoring components during construction.

[0058] The second step involves anchoring the upper part of the geomembrane anchoring strip 8 to the corresponding section of the concrete slope 7 at a predetermined location. Then, the side edge 1C of the dam bottom geomembrane 1B is extended downwards, with the lower part of the corresponding geomembrane anchoring strip 8 positioned between the side edge 1C and the concrete slope 7. The lower part of the geomembrane anchoring strip 8 and the side edge 1C are then anchored together to the concrete slope 7. The geomembrane anchoring strip 8 is a rectangular PVC geomembrane with a thickness of 2-3.5 mm, and a length and width of 10 m and 1 m respectively. Anchor the geomembrane anchoring strip 8 to the contact area of ​​the upstream geomembrane side 1A; at the corner between the upstream face and the bottom of the clay core wall 5, use an additional geomembrane (e.g., a 3mm thick PVC geomembrane) to partially cover and seal the overlapping areas of the upstream geomembrane 1, the dam bottom geomembrane 1B, the upstream geomembrane side 1A, the dam bottom geomembrane side 1C and the geomembrane anchoring strip 8 by welding.

[0059] The third step is to pre-set the bank slope anchor lines 6 on the concrete bank slopes 7 at both ends of the clay core wall 5, and make the projection of the bank slope anchor lines 6 on the cross section of the clay core wall 5 parallel to the direction of water flow a straight line parallel to the upstream face of the clay core wall 5, and the distance between the anchor lines 6 and the upstream face of the clay core wall 5 is 25cm.

[0060] Step 4: Construct the clay core wall 5 at the predetermined location by compacting clay layer by layer. After each layer of clay is compacted, first lay the upstream geomembrane 1 on the upstream face of the clay core wall 5 of that layer. The upstream geomembrane 1 is a 2-3.5mm PVC geomembrane. Anchor the upstream geomembrane sides 1A at both ends of the clay core wall 5 to the corresponding slope concrete 7 along the slope anchoring line 6, and then continue construction of the next layer. The reserved dimension of the upstream geomembrane side 1A is approximately 0.13% ± 0.05% of the length of the trapezoidal lower base of the upstream face of the clay core wall 5, and not less than 25cm.

[0061] Step 5: After the clay core wall 5 is constructed, its cross-section parallel to the water flow direction is trapezoidal, and its upstream face is an inverted trapezoid, with the upper base length of 360m and the lower base length of 190m. The trapezoidal cross-section of the clay core wall 5 parallel to the water flow direction is 55m high, with an upper base length of 4m and a lower base length of 32m. The upstream geomembrane 1 is laid in an "S" shape on the upstream face of the clay core wall 5. Construction is complete.

[0062] Based on the above embodiments, the technical solution of the present invention has the following advantages:

[0063] (1) The clay core wall is partially covered by the upstream geomembrane, the bottom geomembrane, the side of the upstream geomembrane, the side of the bottom geomembrane, the geomembrane anchoring strip, and the horizontal geomembrane. By making special connections and anchors to different parts of the geomembrane, a closed seepage barrier is formed on the upstream surface of the clay core wall, which effectively improves the overall seepage prevention performance of the dam.

[0064] (2) By using two layers of geotextile to sandwich one layer of geomembrane material in the upstream geomembrane, the overall tensile strength and deformation coordination of the geomembrane are significantly improved. This structure can adapt to the deformation of the dam body through the stress redistribution effect of the geotextile, reduce the possibility of hydraulic splitting, and significantly improve the seepage prevention performance and safety of the dam body.

[0065] (3) By setting independent anchoring strips, the side of the upstream geomembrane and the geomembrane extending from the top of the upstream anti-seepage wall towards the bank slope concrete are respectively anchored to the anchoring strips. The side of the upstream geomembrane is anchored at the overlap of the anchoring strip. The anchoring strip allows the two geomembranes to move independently in different directions, so that they can adapt to their respective differential deformations under the connection of the anchoring strips without affecting each other. The side of the upstream geomembrane is anchored to the geomembrane anchoring strip. Under the action of water pressure, the dam body will have horizontal displacement, so that only the upstream geomembrane will deform alone, without affecting the geomembrane at the bottom of the dam. The geomembrane extending from the anchoring part at the top of the upstream anti-seepage wall concrete is connected and anchored to the geomembrane anchoring strip. The deformation of the geomembrane at the bottom of the dam body caused by the uneven settlement of the dam body will not affect the upstream geomembrane. At the same time, a closed anti-seepage system can be formed.

[0066] (4) The geomembrane is used to cover and seal the anchoring area of ​​the seepage barrier wall from the outside of the lower anchoring area to the upper anchoring area. The geomembrane is welded to the surface of the concrete seepage barrier wall outside the upper anchoring area. The sealed area is filled with flexible material to prevent leakage in the anchoring area of ​​the seepage barrier wall, enhance the seepage prevention capacity for weak seepage points, and prevent the anchoring structure from being damaged during construction by filling with flexible material.

[0067] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

[0068] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0069] The apparatus includes not only those elements, but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A geomembrane-clay core wall combined seepage prevention system for earth-rock dams, comprising a core wall, characterized in that, It also includes an upstream cutoff wall, a downstream cutoff wall, bank slope concrete, an upstream geomembrane, a dam bottom geomembrane, geomembrane anchoring strips, and a horizontal geomembrane; the core wall is a clay core wall; the upstream and downstream cutoff walls are respectively fixed at the bottom of the clay core wall; the bank slope concrete is located at both ends of the clay core wall and is respectively provided with bank slope anchoring lines; the upstream geomembrane is laid from the corner between the upstream and bottom surfaces of the clay core wall, along the upstream surface of the clay core wall, until it covers the entire upstream surface of the clay core wall; the upstream geomembrane has upstream geomembrane sides at both ends of the clay core wall; the upstream geomembrane sides are respectively anchored to the bank slope concrete along the corresponding bank slope anchoring lines; the dam bottom geomembrane is located on the clay core wall. The bottom of the core wall is located between the upstream geomembrane and the upstream cutoff wall; the bottom geomembrane is anchored to the upstream cutoff wall; both ends of the bottom geomembrane are close to the bank slope concrete and extend downwards to form bottom geomembrane sides; the geomembrane anchoring strips are located between the corresponding bottom geomembrane sides and the bank slope concrete; the upper part of the geomembrane anchoring strip is anchored to the corresponding bank slope concrete, and the lower part of the geomembrane anchoring strip and the corresponding bottom geomembrane sides are anchored together to the corresponding bank slope concrete; the horizontal geomembrane is located at the bottom of the clay core wall and between the upstream and downstream cutoff walls; the horizontal geomembrane is anchored to both the upstream and downstream cutoff walls.

2. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 1, characterized in that, The cross-section of the clay core wall parallel to the water flow direction is trapezoidal; the upstream face of the clay core wall is an inverted trapezoid.

3. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 1, characterized in that, The upstream and downstream cutoff walls are respectively buried in the foundation of the earth-rock dam; the upstream and downstream cutoff walls are parallel to each other, with the upstream cutoff wall facing upstream of the earth-rock dam and the downstream cutoff wall facing downstream of the earth-rock dam.

4. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 1, characterized in that, The projection of the bank slope anchoring line onto the cross section of the clay core wall parallel to the direction of water flow is a straight line parallel to the upstream surface of the clay core wall. The distance between the projected straight line and the upstream surface of the clay core wall is 0.13% ± 0.05% of the length of the lower base of the trapezoid on the upstream surface of the clay core wall.

5. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 4, characterized in that, The dimensions of the upstream geomembrane side are 0.13% ± 0.05% of the length of the lower base of the trapezoid on the upstream face of the clay core wall, and are not less than the distance between the projected straight line of the bank slope anchoring line and the upstream face of the clay core wall; the dimensions of the dam bottom geomembrane side are 0.13% ± 0.05% of the length of the lower base of the trapezoid on the upstream face of the clay core wall; the upstream geomembrane is composed of two layers of geotextile sandwiching one layer of geomembrane material; the geomembrane anchoring strip is a rectangular PVC geomembrane with a thickness of 2-3.5 mm.

6. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 1, characterized in that, The geomembrane at the bottom of the dam is laid horizontally from the corner between the upstream and bottom surfaces of the clay core wall, along the bottom of the clay core wall to the top of the upstream cutoff wall; the horizontal geomembrane is laid horizontally from the top of the upstream cutoff wall, along the bottom of the clay core wall to the top of the downstream cutoff wall.

7. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 1, characterized in that, The geomembrane at the bottom of the dam is anchored to the upstream cutoff wall, and the horizontal geomembrane is anchored to both the upstream and downstream cutoff walls using double-row bolts arranged in two rows. Each lower row of bolts forms a lower anchorage area, and each upper row of bolts forms an upper anchorage area. Both the geomembrane at the bottom and horizontal geomembranes are laid from the upper anchorage area to the lower anchorage area at the double-row bolt anchorage points. Then, the geomembrane at the bottom and horizontal geomembranes are wrapped and sealed from the lower anchorage area to the upper anchorage area, forming a sealed area filled with flexible material. Finally, the ends of the geomembrane at the bottom and horizontal geomembranes are welded to their respective locations on the top surface of the upstream or downstream cutoff wall.

8. The geomembrane-clay core combined seepage prevention system for earth-rock dams according to claim 7, characterized in that, The geomembrane anchoring strip is anchored to the contact area of ​​the upstream geomembrane side; at the corner between the upstream and bottom surfaces of the clay core wall, additional geomembrane is used to partially cover and seal the overlapping areas of the upstream geomembrane, the dam bottom geomembrane, the upstream geomembrane side, the dam bottom geomembrane side, and the geomembrane anchoring strip by welding.

9. A sealing method for a geomembrane-clay core combined seepage prevention system for earth-rock dams as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Step 1: Install upstream and downstream cutoff walls at predetermined locations on the foundation of the earth-rock dam; lay a horizontal geomembrane between the upstream and downstream cutoff walls for vertical seepage prevention, and anchor the horizontal geomembrane to the top of the upstream and downstream cutoff walls respectively; lay the dam bottom geomembrane horizontally from the corner between the upstream and bottom surfaces of the clay core wall, along the bottom of the clay core wall to the top of the upstream cutoff wall, and anchor the dam bottom geomembrane to the top of the upstream cutoff wall; reserve the side edge of the dam bottom geomembrane. The second step involves anchoring the upper part of the geomembrane anchoring strip to the corresponding section of the slope concrete at a predetermined location. Then, the side of the dam bottom geomembrane is extended downwards, with the lower part of the corresponding geomembrane anchoring strip positioned between the side of the dam bottom geomembrane and the slope concrete. The lower part of the corresponding geomembrane anchoring strip and the side of the dam bottom geomembrane are then anchored together to the slope concrete. At the corner between the upstream and bottom surfaces of the clay core wall, additional geomembrane is used to partially cover and seal the overlapping areas of the upstream geomembrane, the dam bottom geomembrane, the side of the upstream geomembrane, the side of the dam bottom geomembrane, and the geomembrane anchoring strip using welding. The third step is to pre-set the bank slope anchor lines on the concrete bank slopes at both ends of the clay core wall, and make the projection of the bank slope anchor lines on the cross section of the clay core wall parallel to the direction of water flow a straight line parallel to the upstream surface of the clay core wall. Step 4: Construct a clay core wall at the predetermined location by compacting clay layer by layer; after each layer of clay is compacted, first lay the upstream geomembrane on the upstream surface of the clay core wall of that layer, and then anchor the sides of the upstream geomembrane at both ends of the clay core wall to the corresponding slope concrete along the slope anchoring line, and then continue to construct the next layer. Step 5: After the clay core wall is built, its cross-section parallel to the water flow direction is trapezoidal, and its upstream face is an inverted trapezoid; construction is complete.

10. The sealing method according to claim 9, characterized in that, in the first step It also includes: the anchoring connection between the dam bottom geomembrane and the upstream cutoff wall; the anchoring connection between the horizontal geomembrane and the upstream and downstream cutoff walls respectively, using double-row bolts for anchoring, with the bolts arranged in two rows; each lower row bolt anchoring point forms a lower anchoring area, and each upper row bolt anchoring point forms an upper anchoring area; the laying direction of the dam bottom geomembrane and the horizontal geomembrane at the double-row bolt anchoring points is from the upper anchoring area to the lower anchoring area; then, the dam bottom geomembrane and the horizontal geomembrane are respectively wrapped and sealed from the lower side of the lower anchoring area to the upper side of the upper anchoring area to form a sealed area, which is filled with flexible material; finally, the ends of the dam bottom geomembrane and the horizontal geomembrane are welded to their respective positions on the top surface of the upstream or downstream cutoff wall; The second step also includes: anchoring the geomembrane anchoring strip to the contact area of ​​the upstream geomembrane side.

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