Structural design and construction method for improving stress deformation characteristic of concrete faced rockfill dam anti-seepage system on covering layer

Abstract

The invention relates to a structural design and construction method for improving stress deformation characteristics of an anti-seepage system of an upper face plate dam of a covering layer, which belongs to the technical field of earth and rockfill dam buildings and mainly comprises a step-shaped concrete anti-seepage wall, a Z-shaped connecting plate structure, a toe board, a concrete face plate, a supporting plate, a connecting plate weight, a concrete cushion layer and the like. The method comprises the steps that (1) construction of a main body vertical section and a top step section of the step-shaped concrete diaphragm wall is completed; (2) paving an asphalt concrete cushion layer and an inverted filter layer, and mounting a supporting plate; (3) a base plate, a Z-shaped connecting plate structure, a toe board, a concrete panel and a connecting plate weight are installed; and (4) construction of the flexible water stop seam and the peripheral seam is completed before water storage. According to the invention, the Z-shaped connecting plate structure, the connecting plate weight and the supporting plate are coordinated, so that the shearing and opening deformation of the horizontal anti-seepage system is changed from passive deformation resistance to active deformation control; flexible connection of the anti-seepage system is achieved through cooperative deformation of the flexible water stop seams, the reserved deformation joints and the base plates, deformation coordination of the top step section and the vertical section of the body of the anti-seepage wall is achieved under the action of high reservoir water pressure, the tensile stress of the downstream side of the body of the anti-seepage wall is reduced, and the reliability of the anti-seepage system is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of earth-rock dam construction, and relates to a structural design and construction method for improving the stress-deformation characteristics of a face dam anti-seepage system on a covering layer. Background Art

[0002] With the accelerated development of hydropower in high-altitude, geologically complex areas, the geological conditions at dam sites facing key water conservancy projects in my country are becoming significantly more complex. Building dams on deep overburden has become an unavoidable technical challenge. Currently, several high earth-rockfill dams, including those at Shiziping, Huangjinping, Xiabandi, Luding, Pangduo, Yele, and Altash, have been built or are planned in China, all with overburden depths exceeding 100 meters.

[0003] As a core guarantee for dam structural safety, the anti-seepage system exhibits significant mechanical response characteristics and seepage stability risks under deep overburden foundation conditions. According to the current technical requirements of the "Code for Design of Roller-Compacted Earth-Rockfill Dams" (SL 274-2020) and the "Code for Design of Concrete Face Rockfill Dams" (NB / T10871-2021), the typical anti-seepage system for concrete face rockfill dams constructed under deep overburden foundation conditions consists of rigid components such as the concrete face, toe plate, connecting plate, and anti-seepage wall. These components are sealed together using joint water-stop structures. Furthermore, the anti-seepage system is located on the upstream side of the dam body. This spatially decoupled design effectively prevents the dam body's deadweight from directly affecting the anti-seepage structure, significantly reducing the likelihood that the anti-seepage wall will be affected by the coupling effect of dam body deformation. However, there is a two-order-of-magnitude difference in modulus between the overburden foundation soil (typically 50-200 MPa) and the concrete material of the cutoff wall (approximately 30 GPa). This significant difference in material stiffness results in relative displacements at the joint between the connecting plate and the cutoff wall exceeding the allowable deformation threshold of the waterstop structure (typically <100 mm) under sustained reservoir water pressure. When this shear displacement exceeds the deformation adaptability of the joint waterstop structure, the waterstop system seal fails, forming seepage channels and ultimately causing the seepage gradient to exceed the critical value of the overburden soil's seepage resistance, triggering seepage failure. Furthermore, because deformation at the top of the cutoff wall is limited by the connecting plate and toe plate, while the rest of the wall is encased in the overburden on both the upstream and downstream sides, the wall is prone to arching downstream under high reservoir water pressure, resulting in tensile stresses exceeding the tensile strength standard in the downstream portion of the wall.

[0004] Therefore, in order to address the two major problems of "deformation coordination of anti-seepage system joints" and "excessive tensile stress on the downstream side of the anti-seepage wall" existing in traditional face-fill rockfill dams on the overburden foundation, it is urgent to optimize the anti-seepage structure design and deformation control technology during the construction process, so as to improve the stress-deformation characteristics of the anti-seepage structure of the face-fill dam on the deep overburden foundation and ensure the continued safe and stable operation of the dam. Summary of the Invention

[0005] In order to solve the problems of excessive deformation and damage of the joint water-stop structure of the traditional panel rockfill dam on the covering layer foundation due to the modulus difference of two orders of magnitude between the covering layer soil and the concrete anti-seepage system, and excessive tensile stress on the downstream side of the middle part of the anti-seepage wall due to the deformation of the top of the anti-seepage wall being restricted by the connecting plate and the toe plate, the present invention provides a structural design and construction method for improving the stress-deformation characteristics of the anti-seepage system of the panel rockfill dam on the covering layer, which can effectively reduce the vertical shear deformation of the connecting plate water-stop joint and improve the stress characteristics on the downstream side of the middle part of the anti-seepage wall, thereby enhancing the reliability and durability of the anti-seepage system.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A structure for improving the stress-deformation characteristics of the panel dam anti-seepage system on the covering layer, the panel dam anti-seepage system consists of a stepped concrete anti-seepage wall 1, a "Z"-shaped connecting plate structure 2, a toe plate 3, a panel 4, a support plate 5, a pad 6, a flexible water stop 7, a connecting plate weight 8, a peripheral joint 9, an asphalt concrete cushion layer 10, a filter layer 11, and a reserved deformation joint 14.

[0008] The stepped concrete anti-seepage wall 1 consists of two parts: a main vertical section and a top stepped section. The main vertical section is excavated into a trench and cast using a vertical pipe method, while the top stepped section is constructed using a cast-in-place method.

[0009] Furthermore, the upstream side of the stepped concrete cutoff wall 1 contacts the filter layer 11 and the cover layer 12, and the downstream side contacts, from top to bottom, the Z-shaped connecting plate 21 (No. 1), the asphalt concrete cushion layer 10, the dam body rockfill 13, the filter layer 11, and the cover layer 12, thereby extending the seepage path and reducing the amount of seepage. At the same time, the top step of the stepped concrete cutoff wall 1 serves as a supporting structure for installing the Z-shaped connecting plate 21 (No. 1). A backing plate 6 is installed on the horizontal contact surface between the stepped concrete cutoff wall 1 and the Z-shaped connecting plate 21, and a flexible waterstop 7 is provided on the vertical contact surface.

[0010] Furthermore, a No. ① "Z"-shaped connecting plate 21 and several No. ② "Z"-shaped connecting plates 22 are sequentially spliced into a "Z"-shaped connecting plate structure 2; the "Z"-shaped connecting plate structure 2 is installed between the downstream side of the stepped concrete anti-seepage wall 1 and the upstream side of the toe plate 3, and is constructed using a cast-in-place method to transmit the force and reduce the seepage volume.

[0011] Furthermore, the Z-shaped connecting plate 21 (No. 1) consists of a middle horizontal section and a downstream stepped section. The middle horizontal section of the Z-shaped connecting plate 21 (No. 1) is connected to the top stepped section of the stepped concrete cut-off wall 1, while the downstream stepped section of the Z-shaped connecting plate 21 (No. 1) is connected to the Z-shaped connecting plate 22 (No. 2) closest to the upstream side.

[0012] Furthermore, the second Z-shaped connecting plate 22 is composed of an upstream stepped section, an intermediate horizontal section, and a downstream stepped section. The upstream stepped section of the second Z-shaped connecting plate 22 is connected to the downstream stepped section of the first Z-shaped connecting plate 21 (the second Z-shaped connecting plate 22 closest to the upstream side is connected to the first Z-shaped connecting plate 21) or the downstream stepped section of the second Z-shaped connecting plate 22 (the second Z-shaped connecting plates 22 are adjacent to each other); the downstream stepped section of the second Z-shaped connecting plate 22 is connected to the upstream stepped section of the second Z-shaped connecting plate 22 (the second Z-shaped connecting plates 22 are adjacent to each other) or the toe plate 3 (the second Z-shaped connecting plate 22 closest to the downstream side is connected to the toe plate 3).

[0013] Furthermore, the pad 6 is located between the horizontal contact surface between the stepped section of the stepped concrete cut-off wall 1 and the middle horizontal section of the first Z-shaped connecting plate 21; between the horizontal contact surface between the downstream stepped section of the first Z-shaped connecting plate 21 and the upstream stepped section of the second Z-shaped connecting plate 22 closest to the upstream side; between the horizontal contact surface between the upstream stepped section of the second Z-shaped connecting plate 22 and the downstream stepped section of the second Z-shaped connecting plate 22; and between the downstream stepped section of the second Z-shaped connecting plate 22 closest to the downstream side and the horizontal contact surface of the toe plate 3. The pad 6 is made of a material with a relatively low modulus, such as rubber or a flexible composite material, and has a buffering effect, used to reduce the risk of stress concentration and structural cracking in the concrete structure under complex stress.

[0014] Furthermore, the flexible waterstop 7 is located between the vertical direct contact surface between the stepped section of the stepped concrete anti-seepage wall 1 and the middle horizontal section of the No. 1 "Z"-shaped connecting plate 21, between the downstream stepped section of the No. 1 "Z"-shaped connecting plate 21 and the upper vertical direct contact surface of the upstream stepped section of the No. 2 "Z"-shaped connecting plate 22 closest to the upstream side, between the upstream stepped section of the No. 2 "Z"-shaped connecting plate 22 and the upper vertical direct contact surface of the downstream stepped section of the No. 2 "Z"-shaped connecting plate 22, and between the downstream stepped section of the No. 2 "Z"-shaped connecting plate 22 closest to the downstream side and the upper vertical direct contact surface of the toe plate 3. The flexible waterstop 7 has the characteristic of allowing a certain amount of deformation while ensuring water-stopping conditions, so that the top of the stepped concrete anti-seepage wall 1 can move downstream under the action of high reservoir water pressure, so that the deformation of the top stepped section of the stepped concrete anti-seepage wall 1 is coordinated with the deformation of the main vertical section, reducing the tensile stress on the downstream side of the main vertical section, thereby improving the reliability of the anti-seepage system.

[0015] Furthermore, reserved deformation joints 14 are located between the downstream stepped section of the No. 1 "Z"-shaped connecting plate 21 and the lower vertical direct contact surface of the upstream stepped section of the No. 2 "Z"-shaped connecting plate 22 closest to the upstream side; between the upstream stepped section of the No. 2 "Z"-shaped connecting plate 22 and the lower vertical direct contact surface of the downstream stepped section of the No. 2 "Z"-shaped connecting plate 22; and between the downstream stepped section of the No. 2 "Z"-shaped connecting plate 22 closest to the downstream side and the lower vertical direct contact surface of the toe plate 3. The reserved deformation joints 14 and the flexible waterstop joints 7 deform in coordination to achieve a flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure, thereby improving the stress-deformation characteristics of the stepped concrete anti-seepage wall 1, the No. 1 "Z"-shaped connecting plate 21, the No. 2 "Z"-shaped connecting plate 22, and the toe plate 3.

[0016] Furthermore, the support plate 5 is located at the bottom of the reserved deformation joint 14, which is used to reduce the vertical deformation between the No. 1 "Z"-shaped connecting plate 21 and the No. 2 "Z"-shaped connecting plate 22, between adjacent No. 2 "Z"-shaped connecting plates 22, and between the No. 2 "Z"-shaped connecting plate 22 and the toe plate 3, thereby improving the shear and opening deformation of the water stop joint.

[0017] Furthermore, the connecting plate weight 8 is located at the middle horizontal section of the No. ① "Z"-shaped connecting plate 21 and the top of the upstream stepped section of the No. ② "Z"-shaped connecting plate 22, and is used to increase the deadweight of the "Z"-shaped connecting plate structure 2 and reduce the vertical shear deformation of the water stop joint.

[0018] Furthermore, the asphalt concrete 10 is located between the dam body rockfill 13 and the "Z"-shaped connecting plate structure 2 and the toe plate 3, which is used to prevent the bottom of the horizontal anti-seepage structure from being emptied and improve the deformation coordination and anti-seepage function of the horizontal anti-seepage structure.

[0019] A structural construction method for improving the stress-deformation characteristics of a face dam anti-seepage system on a cover layer comprises the following steps:

[0020] The first step is to complete the construction of the first phase main vertical section and the second phase top step section of the stepped concrete anti-seepage wall 1. Specifically:

[0021] Step 1.1: The dam body rockfill 13 is filled layer by layer starting from the dam foundation that meets the construction requirements by means of a vibration rolling method until it reaches the dam top.

[0022] In step 1.2, a construction site is established at the top elevation of the overburden layer upstream of the dam rockfill 13, centered on the central axis of the stepped concrete cutoff wall 1. Using a grab bucket or hydraulic milling machine, a trench with a width of b2 is excavated along the central axis toward the dam axis in the overburden 12, and slurry reinforcement is applied. Then, conventional concrete is poured using the vertical pipe method, completing the first phase of the main vertical section of the stepped concrete cutoff wall 1, with a width of b2 and an elevation of EL1.

[0023] Step 1.3, use the cast-in-place method to complete the construction of the second-phase top step section of the stepped concrete anti-seepage wall 1. The second-phase top step section of the stepped concrete anti-seepage wall 1 includes two horizontal surfaces along the river and one vertical surface. The width of the top horizontal surface along the river is b1 and the elevation is EL2; the width of the bottom horizontal surface along the river is equal to the length h4 of the upper and lower steps of the "Z"-shaped connecting plate along the river; the height of the vertical surface is equal to the total vertical thickness h1 of the "Z"-shaped connecting plate. Among them, b1 is Times b2.

[0024] The second step is to lay the asphalt concrete cushion layer 10, the filter layer 11, and install the support plate 5.

[0025] Step 2.1: Lay horizontally a thickness of 100 mm from the downstream side of the stepped concrete anti-seepage wall 1 to the bottom of the panel 4. The asphalt concrete pad 10 of times h1 is used to prevent the bottom of the horizontal anti-seepage structure from being hollowed out, and has deformation coordination and anti-seepage functions.

[0026] Step 2.2: while laying the asphalt concrete cushion layer 10, install several support plates 5, the length of the support plates along the river is h5. times h2, vertical thickness h6 is Times h1, used to reduce the vertical deformation between No. ① "Z" shaped connecting plate 21 and No. ② "Z" shaped connecting plate 22, between adjacent No. ② "Z" shaped connecting plates 22, and between No. ② "Z" shaped connecting plate 22 and toe plate 3, thereby improving the shear and opening deformation of the water stop joint.

[0027] Step 2.3: Set up filter layers 11 on the upstream and downstream sides of the stepped concrete anti-seepage wall 1, using a vibration rolling method for construction, with a thickness h7 along the river being 1 to 5 times b2.

[0028] The third step is to install the backing plate 6, the first "Z" shaped connecting plate 21, the second "Z" shaped connecting plate 22, the toe plate 3, the panel 4, and the connecting plate weight 8. Specifically:

[0029] Step 3.1: Install a pad 6 on the horizontal surface along the river on the downstream side of the top step of the stepped concrete anti-seepage wall 1, and install a No. ① "Z"-shaped connecting plate 21 and an appropriate number of No. ② "Z"-shaped connecting plates 22 in sequence on the downstream side of the stepped concrete anti-seepage wall 1 toward the dam body and on the upper part of the asphalt concrete cushion layer 10. Use the slipform construction method to cast the panel 4 along the upstream dam slope direction, and the bottom of the panel 4 is in contact with the toe plate 3.

[0030] Furthermore, in step 3.1, the Z-shaped connecting plates 21 (1), 22 (2), and toe plate 3 are all cast in place. Pads 6 are installed on the contact surfaces of the Z-shaped connecting plates 21 (1), 22 (2), and 22 (2) along the river with the toe plate 3.

[0031] Furthermore, in step 3.1, the total vertical thickness of the No. ① "Z" shaped connecting plate 21 and the No. ② "Z" shaped connecting plate 22 is h1, the vertical thickness of the upper part of the step section is h3, the length of the step section along the river is h4, the total length of the No. ② "Z" shaped connecting plate 22 along the river is h2, and the total length of the No. ① "Z" shaped connecting plate 21 along the river is the difference between h2 and h4. Among them, h3 is times h1, h4 times h2.

[0032] Step 3.2, install the connection plate weight 8 at the top of the upstream stepped section of the "Z"-shaped connection plate 21 in the middle horizontal section of the "Z"-shaped connection plate 21 No. ① and the "Z"-shaped connection plate 22 No. ② to increase the deadweight of the "Z"-shaped connection plate 21 No. ① and the "Z"-shaped connection plate 22 No. ②, and reduce the vertical shear deformation of the water stop joint.

[0033] The fourth step is to complete the construction of the flexible water stop joint 7 and the peripheral joint 9 before water storage. Specifically:

[0034] The flexible waterstop joints 7 are located between the vertical direct contact surfaces of the stepped concrete cutoff wall 1 and the middle horizontal section of the first Z-shaped connecting plate 21; between the downstream stepped section of the first Z-shaped connecting plate 21 and the upper vertical direct contact surface of the upstream stepped section of the second Z-shaped connecting plate 22 closest to the upstream side; between the upstream stepped section of the second Z-shaped connecting plate 22 and the upper vertical direct contact surface of the downstream stepped section of the second Z-shaped connecting plate 22; and between the downstream stepped section of the second Z-shaped connecting plate 22 closest to the downstream side and the upper vertical direct contact surface of the toe plate 3. The peripheral joints 9 are located between the downstream side of the toe plate 3 and the concrete face plate 9. The thickness of the flexible waterstop joints 7 along the river is 5 to 20 cm. The flexible water stop joint 7 and the reserved deformation joint 14 deform synergistically to realize the flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure, which is used to improve the stress-deformation characteristics of the stepped concrete anti-seepage wall 1, No. ① "Z"-shaped connecting plate 21, No. ② "Z"-shaped connecting plate 22 and toe plate 3.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The Z-shaped connecting plate structure provided by the present invention adopts a geometric configuration with multiple continuous turns. The geometric deformation of the connecting plate effectively constrains the shear and opening deformation amplitudes of the water stop under complex stress. At the same time, a connecting plate weight is installed on the top of the Z-shaped connecting plate structure, and a support plate is installed on the bottom of the Z-shaped connecting plate structure to reduce the vertical shear deformation between the Z-shaped connecting plate structure and the concrete anti-seepage wall, and between adjacent Z-shaped connecting plates, thereby improving the shear and opening deformation of the water stop. The coordination of the Z-shaped connecting plate structure, the connecting plate weight, and the support plate realizes the transformation of the horizontal anti-seepage system from "passive resistance to change" to "active control of change."

[0037] (2) The flexible waterstop provided by the present invention is located between the upstream and downstream sides of the "Z"-shaped connecting plate structure and its internal vertical contact surface. The flexible waterstop, the reserved deformation joint and the pad deform in coordination to achieve a flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure. This allows the top of the stepped concrete anti-seepage wall to move downstream under the action of high reservoir water pressure, so that the deformation of the top step section of the stepped concrete anti-seepage wall is coordinated with the deformation of the main vertical section, reducing the tensile stress on the downstream side of the main vertical section, thereby improving the reliability of the anti-seepage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the design scheme of the anti-seepage structure in the embodiment of the application of the present invention.

[0039] Figure 2 It is a partial schematic diagram of the anti-seepage structure in the embodiment of the present invention.

[0040] Figure 3 It is a schematic diagram of the dimension marking of the anti-seepage structure in the embodiment of the application of the present invention.

[0041] Figure 4 It is a schematic structural diagram of the "Z"-shaped connecting plate No. ① and the "Z"-shaped connecting plate No. ② in the embodiment of the present invention.

[0042] In the figure: 1 stepped concrete anti-seepage wall; 2 "Z" type connecting plate structure; 21 No. ① "Z" type connecting plate; 22 No. ② "Z" type connecting plate; 3 toe plate; 4 concrete face plate; 5 support plate; 6 pad; 7 flexible water stop joint; 8 connecting plate weight; 9 perimeter joint; 10 asphalt concrete cushion layer; 11 filter layer; 12 cover layer; 13 dam body rockfill; 14 reserved expansion joint; EL1 first phase stepped concrete anti-seepage wall main vertical section elevation; EL2 second phase stepped Elevation of the top step of the concrete cut-off wall; b1 width of the top of the stepped concrete cut-off wall; b2 width of the vertical section of the main body of the stepped concrete cut-off wall; h1 total vertical thickness of the "Z"-shaped connecting plate structure; h2 total length of the No. ② "Z"-shaped connecting plate along the river; h3 vertical thickness of the upper part of the stepped section of the "Z"-shaped connecting plate structure; h4 length of the stepped section of the "Z"-shaped connecting plate structure along the river; h5 length of the support plate along the river; h6 vertical thickness of the support plate; h7 thickness of the filter layer along the river. DETAILED DESCRIPTION

[0043] In order to make the technical solutions, objectives and advantages of the embodiments of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and specific engineering cases.

[0044] The words “comprises”, “includes”, “consist of” and similar expressions used in the description and claims of the present patent application are intended to indicate that the components, structures or operating steps listed after “comprises” or between “consist of” do not exclude the existence or addition of one or more other components, structures or operating steps. The words “upstream side”, “downstream side”, “top”, “bottom” and the like used in the description and claims only indicate relative positional relationships. When the absolute position of the described object changes, the relative position may also change accordingly. The words “connection” and “installation” used in the description and claims should be understood in a broad sense, such as: sliding connection, mechanical connection, fixed connection, direct connection, indirect connection, etc. It should be pointed out in particular that the words “No. ①” and “No. ②” used in the description and claims are only used to distinguish the types of components and do not indicate any quantity, order or importance.

[0045] The present invention provides a structural design and construction method for improving the stress-deformation characteristics of the anti-seepage system of the face dam on the cover layer, such as Figures 1 to 4 As shown, the concrete face dam anti-seepage system consists of a stepped concrete anti-seepage wall 1, a "Z"-shaped connecting plate structure 2, a toe plate 3, a panel 4, a support plate 5, a pad 6, a flexible water stop 7, a connecting plate weight 8, a peripheral joint 9, an asphalt concrete cushion layer 10, a filter layer 11, and a reserved expansion joint 14.

[0046] In this example, an asphalt concrete face dam on a deep overburden layer is used as an engineering case study. The overburden top elevation is 2950m, the dam crest elevation is 3030m, the dam height is 80m, the crest width is 10m, and the upstream slope of the dam body is 1:1.6, and the downstream slope is 1:1.8. The thickness of the concrete face dam varies from crest to bottom by 0.4m + 0.0035h, where h is the height from the dam crest. A reinforced concrete toe plate is installed at the bottom of the face plate, 4.0m wide and 1.2m high. The dam foundation is protected against seepage using a suspended anti-seepage wall. The stepped concrete anti-seepage wall 1 is 150m deep, with the axis of the anti-seepage wall 12m from the toe plate.

[0047] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, the stepped concrete anti-seepage wall 1 consists of two parts: a main vertical section and a top stepped section. The width b2 of the main vertical section is 1.5m, and the top width b1 is 0.8m. The main vertical section is excavated into a trench and cast by the vertical rising conduit method, and the top stepped section is constructed by the cast-in-place method.

[0048] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, the upstream side of the stepped concrete cutoff wall 1 contacts the filter layer 11 and the cover layer 12, while the downstream side contacts, from top to bottom, the Z-shaped connecting plate 21 (No. 1), the asphalt concrete cushion layer 10, the dam rockfill material 13, the filter layer 11, and the cover layer 12, thereby extending the seepage path and reducing the amount of seepage. Furthermore, the top step of the stepped concrete cutoff wall 1 serves as a support structure for mounting the Z-shaped connecting plate 21 (No. 1). A backing plate 6 is installed on the horizontal contact surface between the stepped concrete cutoff wall 1 and the Z-shaped connecting plate 21, and a flexible waterstop 7 is provided on the vertical contact surface.

[0049] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, a No. ① "Z"-shaped connecting plate 21 and two No. ② "Z"-shaped connecting plates 22 are sequentially spliced into a "Z"-shaped connecting plate structure 2; the "Z"-shaped connecting plate structure 2 is installed between the downstream side of the stepped concrete anti-seepage wall 1 and the upstream side of the toe plate 3, and is constructed using a cast-in-place method to transmit the force and reduce the seepage volume.

[0050] like Figure 1 、 Figure 2 and Figure 3As shown, in this embodiment, the first "Z"-shaped connecting plate 21 consists of two parts: an intermediate horizontal section and a downstream stepped section. The second "Z"-shaped connecting plate 22 consists of three parts: an upstream stepped section, an intermediate horizontal section, and a downstream stepped section. The total vertical thickness h1 of the "Z"-shaped connecting plate structure 2 is 1.2m, the total length h2 of the second "Z"-shaped connecting plate in the downstream direction is 4.0m, the vertical thickness h3 of the upper portion of the stepped section of the "Z"-shaped connecting plate structure is 0.85m, and the length h4 of the stepped section of the "Z"-shaped connecting plate structure in the downstream direction is 0.50m. The intermediate horizontal section of the first "Z"-shaped connecting plate 21 is connected to the top stepped section of the stepped concrete cutoff wall 1, and the downstream stepped section of the first "Z"-shaped connecting plate 21 is connected to the second "Z"-shaped connecting plate 22 closest to the upstream side. The upstream step section of the No. ② "Z"-shaped connecting plate 22 is connected to the downstream step section of the No. ① "Z"-shaped connecting plate 21 (the No. ② "Z"-shaped connecting plate 22 closest to the upstream side is connected to the No. ① "Z"-shaped connecting plate 21) or the downstream step section of the No. ② "Z"-shaped connecting plate 22 (the No. ② "Z"-shaped connecting plates 22 are adjacently connected); the downstream step section of the No. ② "Z"-shaped connecting plate 22 is connected to the upstream step section of the No. ② "Z"-shaped connecting plate 22 (the No. ② "Z"-shaped connecting plates 22 are adjacently connected) or the toe plate 3 (the No. ② "Z"-shaped connecting plate 22 closest to the downstream side is connected to the toe plate 3).

[0051] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, the pad 6 is located between the horizontal contact surface between the stepped section of the stepped concrete cutoff wall 1 and the middle horizontal section of the first Z-shaped connecting plate 21; between the horizontal contact surface between the downstream stepped section of the first Z-shaped connecting plate 21 and the upstream stepped section of the second Z-shaped connecting plate 22 closest to the upstream side; between the horizontal contact surface between the upstream stepped section of the second Z-shaped connecting plate 22 and the downstream stepped section of the second Z-shaped connecting plate 22; and between the downstream stepped section of the second Z-shaped connecting plate 22 closest to the downstream side and the horizontal contact surface of the toe plate 3. The pad 6 is made of a material with a relatively low modulus, such as rubber or a flexible composite material, and has a buffering effect, used to reduce the risk of stress concentration and structural cracking in the concrete structure under complex stress.

[0052] like Figure 1 、 Figure 2 and Figure 3As shown, in this embodiment, the flexible waterstop 7 is located between the vertical direct contact surface between the stepped section of the stepped concrete cutoff wall 1 and the middle horizontal section of the first Z-shaped connecting plate 21; between the downstream stepped section of the first Z-shaped connecting plate 21 and the upper vertical direct contact surface of the upstream stepped section of the second Z-shaped connecting plate 22 closest to the upstream side; between the upstream stepped section of the second Z-shaped connecting plate 22 and the upper vertical direct contact surface of the downstream stepped section of the second Z-shaped connecting plate 22; and between the downstream stepped section of the second Z-shaped connecting plate 22 closest to the downstream side and the upper vertical direct contact surface of the toe plate 3. The flexible waterstop 7 has the characteristic of allowing a certain amount of deformation while ensuring water-stopping conditions. This allows the top of the stepped concrete cutoff wall 1 to move downstream under high reservoir water pressure, coordinates the deformation of the top stepped section of the stepped concrete cutoff wall 1 with the main vertical section, reduces the tensile stress on the downstream side of the main vertical section, and improves the reliability of the anti-seepage system.

[0053] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, the reserved expansion joints 14 are located between the downstream stepped section of the first Z-shaped connecting plate 21 and the lower vertical direct contact surface of the upstream stepped section of the second Z-shaped connecting plate 22 closest to the upstream side; between the upstream stepped section of the second Z-shaped connecting plate 22 and the lower vertical direct contact surface of the downstream stepped section of the second Z-shaped connecting plate 22; and between the downstream stepped section of the second Z-shaped connecting plate 22 closest to the downstream side and the lower vertical direct contact surface of the toe plate 3. The reserved expansion joints 14 and the flexible waterstop joints 7 deform in coordination to achieve a flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure, thereby improving the stress-deformation characteristics of the stepped concrete anti-seepage wall 1, the first Z-shaped connecting plate 21, the second Z-shaped connecting plate 22, and the toe plate 3.

[0054] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, the support plate 5 is located at the bottom of the reserved deformation joint 14, and is used to reduce vertical deformation between the Z-shaped connecting plate 21 (No. 1) and the Z-shaped connecting plate 22 (No. 2), between adjacent Z-shaped connecting plates 22 (No. 2), and between the Z-shaped connecting plate 22 and the toe plate 3, thereby improving the shear and opening deformation of the waterstop joint. The support plate has a riverside length h5 of 1.50m and a vertical thickness h6 of 0.50m.

[0055] like Figure 1 、 Figure 2 and Figure 3As shown, in this embodiment, the connecting plate weight 8 is located at the middle horizontal section of the No. ① "Z"-shaped connecting plate 21 and the top of the upstream stepped section of the No. ② "Z"-shaped connecting plate 22, wherein the connecting plate weight 8 is a hemisphere with a radius of 0.6m, which is used to increase the deadweight of the "Z"-shaped connecting plate structure 2 and reduce the vertical shear deformation of the water stop joint.

[0056] like Figure 1 、 Figure 2 and Figure 3 As shown, in this embodiment, asphalt concrete 10 is located between the dam body rockfill 13 and the "Z"-shaped connecting plate structure 2 and the toe plate 3, and is used to prevent the bottom of the horizontal anti-seepage structure from being emptied, thereby improving the deformation coordination and anti-seepage function of the horizontal anti-seepage structure.

[0057] The construction of this embodiment includes the following steps:

[0058] The first step is to complete the construction of the first phase main vertical section and the second phase top step section of the stepped concrete anti-seepage wall 1. Specifically:

[0059] Step 1.1: The dam body rockfill 13 is filled layer by layer starting from the dam foundation that meets the construction requirements by means of vibration rolling method until it reaches the dam top elevation of 3030m.

[0060] In step 1.2, a construction site was established at an elevation of 2950m above the top of the overburden layer upstream of the dam rockfill 13, centered on the central axis of the stepped concrete cutoff wall 1. Using a grab bucket or hydraulic milling machine, a 1.5m-wide trench was excavated along this central axis toward the dam axis in the overburden 12, and slurry was used to reinforce the trench. Then, conventional concrete was poured using the direct-lift conduit method, completing the first phase of the main vertical section of the stepped concrete cutoff wall 1.

[0061] Step 1.3, use the cast-in-place method to complete the construction of the second-phase top step section of the stepped concrete anti-seepage wall 1. The second-phase top step section of the stepped concrete anti-seepage wall 1 includes two horizontal surfaces along the river and one vertical surface. The width of the top horizontal surface along the river is 0.8m; the width of the bottom horizontal surface along the river is 0.7m, and the height of the vertical surface is 1.20m.

[0062] The second step is to lay the asphalt concrete cushion layer 10, the filter layer 11, and install the support plate 5.

[0063] Step 2.1: a 0.5m thick asphalt concrete mat 10 is horizontally laid from the downstream side of the stepped concrete anti-seepage wall 1 to the lower part of the panel 4 to prevent the bottom of the horizontal anti-seepage structure from being emptied and to have deformation coordination and anti-seepage functions.

[0064] Step 2.2: while laying the asphalt concrete cushion layer 10, install three support plates 5 to reduce the vertical deformation of the upstream and downstream step sections of the "Z"-shaped connecting plate structure 2, thereby improving the shear and opening deformation of the water stop joint.

[0065] Step 2.3: setting up filter layers 11 on the upstream and downstream sides of the stepped concrete anti-seepage wall 1, and constructing them by using a vibration rolling method.

[0066] The third step is to install the backing plate 6, the "Z"-shaped connecting plate structure 2, the toe plate 3, the panel 4, and the connecting plate weight 8. Specifically:

[0067] Step 3.1: Install a pad 6 on the horizontal surface of the stepped concrete anti-seepage wall 1 along the river. Install a No. ① "Z"-shaped connecting plate 21 and two No. ② "Z"-shaped connecting plates 22 in sequence on the downstream side of the stepped concrete anti-seepage wall 1 toward the dam body and on the upper part of the asphalt concrete cushion layer 10. Cast the panel 4 along the upstream dam slope using the slipform construction method, and the bottom of the panel 4 is in contact with the toe plate 3.

[0068] Furthermore, in step 3.1, the Z-shaped connecting plate 21 (1), the Z-shaped connecting plate 22 (2), and the toe plate 3 are all cast in place. Pads 6 are installed along the river-facing contact surfaces of the Z-shaped connecting plate 21 (1) and the Z-shaped connecting plate 22 (2), the Z-shaped connecting plate 22 (2) and the Z-shaped connecting plate 22 (2), and the Z-shaped connecting plate 22 (2) and the toe plate 3.

[0069] Furthermore, in step 3.1, the support plate 5 is located at the bottom of the deformation joint 14 reserved between the No. ① "Z"-shaped connecting plate 21 and the No. ② "Z"-shaped connecting plate 22, the No. ② "Z"-shaped connecting plate 22 and the No. ② "Z"-shaped connecting plate 22, and the No. ② "Z"-shaped connecting plate 22 and the toe plate 3.

[0070] Step 3.2: Install the connection plate weight 8 at the middle horizontal section of the No. ① "Z"-shaped connection plate 21 and the top of the upstream stepped section of the No. ② "Z"-shaped connection plate 22 to increase the deadweight of the "Z"-shaped connection plate structure 2 and reduce the vertical shear deformation of the water stop joint.

[0071] The fourth step is to complete the construction of the flexible water stop joint 7 and the peripheral joint 9 before water storage. Specifically:

[0072] The flexible water stop joint 7 is arranged between the vertical direct contact surface between the step section of the stepped concrete anti-seepage wall 1 and the middle horizontal section of the No. 1 "Z"-shaped connecting plate 21, between the downstream step section of the No. 1 "Z"-shaped connecting plate 21 and the upper vertical direct contact surface of the upstream step section of the No. 2 "Z"-shaped connecting plate 22 closest to the upstream side, between the upstream step section of the No. 2 "Z"-shaped connecting plate 22 and the upper vertical direct contact surface of the downstream step section of the No. 2 "Z"-shaped connecting plate 22, and between the downstream step section of the No. 2 "Z"-shaped connecting plate 22 closest to the downstream side and the upper vertical direct contact surface of the toe plate 3; the peripheral seam 9 is located between the downstream side of the toe plate 3 and the concrete panel 4, and the thickness of the flexible water stop joint 7 along the river direction is 10 cm. The flexible water stop joint 7 and the reserved deformation joint 14 deform synergistically to achieve a flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure, which is used to improve the stress-deformation characteristics of the stepped concrete anti-seepage wall 1, the "Z"-shaped connecting plate structure 2 and the toe plate 3.

[0073] The above-described embodiments are merely implementation methods of the present invention and should not be understood as limiting the scope of the patent of the present invention. It should be pointed out that for technicians in the same field, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A structure for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer, characterized in that: The structure as a concrete panel dam anti-seepage system comprises a stepped concrete anti-seepage wall (1), a "Z"-shaped connecting plate structure (2), a toe plate (3), a concrete panel (4), a support plate (5), a pad (6), a flexible water stop joint (7), a connecting plate weight (8), a peripheral joint (9), an asphalt concrete cushion layer (10), a filter layer (11), and a reserved deformation joint (14); The stepped concrete anti-seepage wall (1) consists of two parts: a main vertical section and a top stepped section; The "Z"-shaped connecting plate structure (2) is composed of a No. ① "Z"-shaped connecting plate (21) and a plurality of No. ② "Z"-shaped connecting plates (22), wherein the No. ① "Z"-shaped connecting plate (21) is composed of two parts: an intermediate horizontal section and a downstream stepped section; the No. ② "Z"-shaped connecting plate (22) is composed of three parts: an upstream stepped section, an intermediate horizontal section, and a downstream stepped section; the "Z"-shaped connecting plate structure (2) is installed between the downstream side of the stepped concrete anti-seepage wall (1) and the upstream side of the toe plate (3).

2. The structure for improving the stress-deformation characteristics of the anti-seepage system of the face dam on the cover layer according to claim 1, characterized in that: The upstream side of the stepped concrete anti-seepage wall (1) contacts the filter layer (11) and the cover layer (12), and the downstream side contacts the No. ① "Z"-shaped connecting plate (21), the asphalt concrete cushion layer (10), the dam body rockfill (13), the filter layer (11) and the cover layer (12) in sequence from top to bottom; at the same time, a pad (6) is installed on the horizontal contact surface between the stepped concrete anti-seepage wall (1) and the No. ① "Z"-shaped connecting plate (21), and a flexible water stop joint (7) is provided on the vertical direct contact surface.

3. The structure for improving the stress-deformation characteristics of the anti-seepage system of the face dam on the cover layer according to claim 1, characterized in that: The flexible water stop joint (7) is located between the stepped section of the stepped concrete anti-seepage wall (1) and the vertical direct contact surface of the middle horizontal section of the No. ① "Z"-shaped connecting plate (21), between the downstream stepped section of the No. ① "Z"-shaped connecting plate (21) and the upper vertical direct contact surface of the upstream stepped section of the No. ② "Z"-shaped connecting plate (22) closest to the upstream side, between the upstream stepped section of the No. ② "Z"-shaped connecting plate (22) and the upper vertical direct contact surface of the downstream stepped section of the No. ② "Z"-shaped connecting plate (22), and between the downstream stepped section of the No. ② "Z"-shaped connecting plate (22) closest to the downstream side and the upper vertical direct contact surface of the toe plate (3).

4. The structure for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer according to claim 1, characterized in that: The reserved deformation joint (14) is located between the stepped section of the stepped concrete anti-seepage wall (1) and the middle horizontal section of the No. 1 "Z"-shaped connecting plate (21) in a vertical direct contact surface, between the downstream stepped section of the No. 1 "Z"-shaped connecting plate (21) and the upper vertical direct contact surface of the upstream stepped section of the No. 2 "Z"-shaped connecting plate (22) closest to the upstream side, between the upstream stepped section of the No. 2 "Z"-shaped connecting plate (22) and the upper vertical direct contact surface of the downstream stepped section of the No. 2 "Z"-shaped connecting plate (22), and between the downstream stepped section of the No. 2 "Z"-shaped connecting plate (22) closest to the downstream side and the upper vertical direct contact surface of the toe plate (3); the reserved deformation joint (14) and the flexible water stop joint (7) are deformed in coordination to realize the flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure.

5. The structure for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer according to claim 1, characterized in that: The support plate (5) is located at the bottom of the reserved deformation joint (14); The connecting plate weight (8) is located at the middle horizontal section of the No. ① "Z"-shaped connecting plate (21) and the top of the upstream stepped section of the No. ② "Z"-shaped connecting plate (22); The pad (6) is located between the stepped section of the stepped concrete anti-seepage wall (1) and the horizontal contact surface of the middle horizontal section of the No. 1 "Z"-shaped connecting plate (21), between the downstream stepped section of the No. 1 "Z"-shaped connecting plate (21) and the horizontal contact surface of the upstream stepped section of the No. 2 "Z"-shaped connecting plate (22) closest to the upstream side, between the upstream stepped section of the No. 2 "Z"-shaped connecting plate (22) and the horizontal contact surface of the downstream stepped section of the No. 2 "Z"-shaped connecting plate (22), and between the downstream stepped section of the No. 2 "Z"-shaped connecting plate (22) closest to the downstream side and the horizontal contact surface of the toe plate (3).

6. A construction method for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, completing the construction of the first phase main vertical section and the second phase top step section of the stepped concrete anti-seepage wall (1); Step 2: laying an asphalt concrete cushion layer (10), a filter layer (11), and installing a support plate (5); Step 3, installing the pad (6), the "Z"-shaped connecting plate structure (2), the toe plate (3), the concrete panel (4), and the connecting plate weight (8); Step 4, before water storage, complete the construction of the flexible water stop joint (7) and the peripheral joint (9).

7. The construction method for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer according to claim 6, wherein step 1 specifically comprises the following steps: Step 1.1, the dam body rockfill (13) is filled layer by layer starting from the dam foundation that meets the construction requirements until it reaches the dam top by using the vibration rolling method; Step 1.2: At the top elevation of the covering layer on the upstream side of the dam body rockfill (13), a construction site is established with the central axis of the location of the stepped concrete anti-seepage wall (1) as the center. The covering layer (12) is excavated into a groove along the central axis toward the dam axis, with a groove width of b2, and mud wall protection is used; then, ordinary concrete is poured to complete the construction of the first phase of the main vertical section of the stepped concrete anti-seepage wall (1), with a width of b2 and an elevation of EL1; Step 1.3, the second-phase top step section of the stepped concrete anti-seepage wall (1) is completed by cast-in-place method. The second-phase top step section of the stepped concrete anti-seepage wall (1) includes two horizontal planes along the river and one vertical plane. The width of the top horizontal plane along the river is b1 and the elevation is EL2. The width of the bottom horizontal plane along the river is equal to the length h4 of the step section along the river of the "Z" type connecting plate structure. The height of the vertical plane is equal to the total vertical thickness h1 of the "Z" type connecting plate structure. Wherein, b1 is Times b2.

8. According to the construction method of a structure for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer of claim 6, said step 2 specifically comprises the following steps: Step 2.1: Lay horizontally a thickness of 100mm from the downstream side of the stepped concrete anti-seepage wall (1) to the lower part of the concrete panel (4). times h1 of the asphalt concrete mat 10; Step 2.2: while laying the asphalt concrete cushion layer (10), install several support plates (5). The length h5 of the support plates along the river is times h2, vertical thickness h6 is times h1, used to reduce the vertical deformation of the "Z"-shaped connecting plate structure (2); Step 2.3, setting up filter layers (11) on the upstream and downstream sides of the stepped concrete anti-seepage wall (1), using a vibration rolling method for construction, with a thickness h7 along the river being 1 to 5 times b2.

9. According to the construction method of a structure for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer of claim 6, said step 3 specifically comprises the following steps: Step 3.1, a pad (6) is installed on the river-oriented horizontal surface on the downstream side of the top step of the stepped concrete anti-seepage wall (1), and a No. ① "Z"-shaped connecting plate (21), a No. ② "Z"-shaped connecting plate (22) and a toe plate (3) are installed in sequence on the downstream side of the stepped concrete anti-seepage wall (1) toward the dam body and the upper part of the asphalt concrete cushion layer (10), and a concrete panel (4) is cast along the upstream dam slope using a slipform construction method, with the bottom of the concrete panel (4) in contact with the toe plate (3); specifically: The Z-shaped connecting plate (21) No. ①, the Z-shaped connecting plate (22) No. ② and the toe plate (3) are all constructed by cast-in-place method; the vertical total thickness of the Z-shaped connecting plate (21) No. ① and the Z-shaped connecting plate (22) No. ② is h1, the vertical thickness of the upper part of the step section is h3, the length of the step section along the river is h4, the total length of the Z-shaped connecting plate 22 along the river is h2, and the total length of the Z-shaped connecting plate 21 along the river is the difference between h2 and h4; wherein, h3 is times h1, h4 times h2; Step 3.2, install the connection plate weight 8 on the top of the upstream step section of the "Z"-shaped connection plate 2 in the middle horizontal section of the "Z"-shaped connection plate (21) No. ① and the "Z"-shaped connection plate (22) No. ② to increase the deadweight of the "Z"-shaped connection plate structure (2) and reduce the vertical shear deformation of the water stop joint.

10. According to the construction method of a structure for improving the stress-deformation characteristics of the anti-seepage system of a face dam on the cover layer of claim 6, said step 4 specifically comprises: The flexible water stop joint (7) is provided between the vertical direct contact surface between the stepped section of the stepped concrete anti-seepage wall (1) and the middle horizontal section of the No. ① "Z" shaped connecting plate (21), between the downstream stepped section of the No. ① "Z" shaped connecting plate (21) and the upper vertical direct contact surface of the upstream stepped section of the No. ② "Z" shaped connecting plate (22) closest to the upstream side, between the upstream stepped section of the No. ② "Z" shaped connecting plate (22) and the upper vertical direct contact surface of the downstream stepped section of the No. ② "Z" shaped connecting plate (22), and between the downstream stepped section of the No. ② "Z" shaped connecting plate (22) closest to the downstream side. The invention relates to a method for improving the stress-deformation characteristics of the stepped concrete anti-seepage wall (1), the Z-shaped connecting plate (22), and the upper vertical contact surface of the toe plate (3); a peripheral joint (9) is located between the downstream side of the toe plate (3) and the concrete panel 9; wherein the thickness of the flexible water stop joint (7) along the river direction is 5 to 20 cm; the flexible water stop joint (7) and the reserved deformation joint (14) are synergistically deformed to realize the flexible connection of the anti-seepage wall-connecting plate-toe plate anti-seepage structure, and is used to improve the stress-deformation characteristics of the stepped concrete anti-seepage wall (1), the Z-shaped connecting plate structure (2), and the toe plate (3).

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