Novel Compressible Structural Joints for High Concrete-Faced Rockfill Dams

Abstract

This utility model belongs to the field of hydropower station construction technology, specifically relating to a novel compressive structural joint for high concrete-faced rockfill dams. It includes a compressive concrete face and a T-shaped concrete cover plate, both formed by two-stage casting, with the T-shaped cover plate cast on top of the compressive concrete face. A waterstop is installed at the bottom between the compressive concrete face and the T-shaped cover plate; the upper part of the waterstop is filled with asphalt-impregnated fir board, and asphalt felt is placed between the cast surfaces of the compressive concrete face and the T-shaped cover plate. This novel compressive structural joint, through its innovative double-joint design and the filling of the joint with asphalt-impregnated fir board—a compressible filler—effectively absorbs the axial deformation of the high concrete-faced rockfill dam, significantly reducing the horizontal compressive strain of the face and fundamentally avoiding the problem of face crushing failure due to excessive compressive stress.

Description

Technical Field

[0001] This utility model belongs to the field of hydropower station construction technology, specifically relating to a novel compressive structural joint for high concrete-faced rockfill dams. Background Technology

[0002] Concrete-faced rockfill dams have become one of the important dam types in the field of water conservancy and hydropower engineering at home and abroad due to their significant advantages such as strong adaptability to terrain and geological conditions, simple construction procedures, and low engineering investment costs.

[0003] As a core component of the seepage prevention system for concrete-faced rockfill dams, the joint sealing system is also a weak link in the dam structure. Its integrity and reliability directly determine whether the dam can operate safely and stably. Therefore, joint sealing design has become a key issue in the seepage prevention design of concrete-faced rockfill dams. In actual engineering practice, many concrete-faced rockfill dams at home and abroad have experienced serious dam leakage problems due to damage to the joint sealing structure, posing a direct threat to the safety of the project: During the first impoundment stage of the Mohari concrete-faced rockfill dam in Lesotho, Africa, the upper part of the concrete panel along the longitudinal joint of the riverbed section experienced extrusion damage, and the damaged area continued to extend to the bottom of the wave wall, seriously affecting the seepage prevention performance of the dam; During the operation of the Barragrande concrete-faced rockfill dam in Brazil, extrusion damage occurred at the longitudinal joint between panels No. 19 and No. 20, and the dam leakage reached as high as 428 L / s, and the extrusion damage range further extended to the top of the second-phase panel. Such longitudinal joint compression damage not only leads to concentrated seepage in the dam, endangering the overall safety of the dam, but also presents challenges such as complex procedures, high costs, and long cycles in subsequent repair work, which places higher demands on the structural design of the pressure joints between the panels.

[0004] According to existing engineering practices, conventional compressive joints employ a rigid joint structure design, applying only a 6mm thick layer of asphalt latex between the joints, relying entirely on the concrete's own compressive strength to resist the compressive stress between the panels. However, for high-faced rockfill dams, this conventional structure has significant limitations: during dam impoundment, the dam body is subjected to upstream water pressure, resulting in a significant increase in its deformation; simultaneously, some high-faced rockfill dams are prone to panel rotation due to inconsistent filling heights in different parts of the dam body. Both of these situations lead to concentrated compressive strain at the top of the joint. Especially under conditions of rapid water level rise in high-faced rockfill dams, the dam body experiences more severe stress and deformation, greatly increasing the likelihood of panel deformation and rotation. Conventional rigid joint structures are ill-suited to such deformations, easily leading to panel crushing failure. Therefore, developing a new type of compressive joint structure that can adapt to the working conditions of high-faced rockfill dams and possesses excellent deformation resistance and seismic performance has become an urgent technical problem to be solved in the field of water conservancy and hydropower engineering. Utility Model Content

[0005] The purpose of this invention is to provide a novel compressive structural joint for high concrete-faced rockfill dams, in order to solve the problems existing in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a novel compressive structural joint for high concrete-faced rockfill dams, comprising a compressive concrete face and a T-shaped concrete cover plate, wherein the compressive concrete face and the T-shaped concrete cover plate are formed by two-stage casting, and the T-shaped concrete cover plate is cast above the compressive concrete face; a waterstop is provided at the bottom between the compressive concrete face and the T-shaped concrete cover plate, the waterstop being filled with polyurethane foam and PVC rods; the upper part of the waterstop is filled with asphalt-impregnated fir board, and asphalt felt is provided between the casting surfaces of the compressive concrete face and the T-shaped concrete cover plate; the triangular areas formed by the T-shaped concrete cover plate and the compressive concrete face are filled with flexible filler, and PVC rods are also provided within the triangular areas; a three-component rubber plate is provided on the outside of the flexible filler, and the three-component rubber plate is fixed to the compressive concrete face and the T-shaped concrete cover plate by expansion bolts and steel flat steel to achieve enclosure of the flexible filler.

[0007] Preferably, both the compressive concrete panel and the T-shaped concrete cover are reinforced concrete structures.

[0008] Preferably, the water stop is a W1 type water stop, and the material of the water stop is copper.

[0009] Preferably, the polyurethane foam is made of polyurethane, or a polymer material with the same, similar or better properties than polyurethane.

[0010] Preferably, the PVC rod has a tensile strength of not less than 10 MPa and a hardness of not less than 65 degrees.

[0011] Preferably, the thickness of the asphalt-impregnated fir board can be adjusted according to the deformation requirements of the high concrete-faced rockfill dam.

[0012] Preferably, the flexible filler is made of a polymer flexible filler.

[0013] Preferably, the three-component rubber sheet is an EPDM (ethylene propylene diene monomer) GB rubber composite sheet.

[0014] Preferably, the expansion bolts and steel flat bars are made of stainless steel, or are metal materials with the same, similar or better corrosion resistance than stainless steel.

[0015] The beneficial effects of this utility model are as follows: This novel compressive structural joint adopts an innovative double-joint structure design and fills the joint with asphalt-impregnated fir board, a compressible filler, which can effectively absorb the axial deformation of the high-face rockfill dam, significantly reduce the horizontal compressive strain of the face panel, and fundamentally avoid the problem of face panel crushing failure caused by excessive compressive stress. At the same time, the chamfer design at the joint of the face panels is eliminated, increasing the thickness of the face panel joint itself, further enhancing the compressive strength of the face panel, making the face panel more adaptable to the problem of uneven deformation caused by the settlement of the dam body or earthquakes, and greatly improving the safety and stability of the face panel structure.

[0016] Furthermore, by pouring the compressive concrete panel and T-shaped concrete cover plate in two stages, this structure can reduce the impact of the concrete's own temperature stress on the panel structure. Combined with the synergistic effect of components such as W1 type copper waterstop, polymer flexible filler, and EPDM GB rubber composite plate, it forms multiple reliable seepage prevention and deformation resistance lines. It not only has excellent deformation resistance and seismic performance, but also ensures good water-stopping effect. It effectively solves the problem of joint stress concentration and leakage hazards caused by large dam deformation and water level fluctuations in high-face rockfill dams, providing strong support for the safe and stable operation of the dam. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model; 1. Compressed concrete panel; 2. T-shaped concrete cover plate; 3. Waterstop; 4. Polyurethane foam; 5. PVC rod; 6. Asphalt-impregnated fir board; 7. Asphalt felt; 8. Flexible filler; 9. Tri-composite rubber sheet; 10. Expansion bolt; 11. Steel flat bar. Detailed Implementation

[0018] In the description of this disclosure, it should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description, and are not intended to 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 disclosure.

[0019] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing" 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, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0021] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings and preferred embodiments.

[0022] See appendix Figure 1 A novel compressive structural joint for high concrete-faced rockfill dams includes a compressive concrete face 1 and a T-shaped concrete cover 2. The compressive concrete face 1 and the T-shaped concrete cover 2 are two-stage casting structures, and the T-shaped concrete cover 2 is cast on top of the compressive concrete face 1. A waterstop 3 is provided at the bottom between the compressible concrete panel 1 and the T-shaped concrete cover plate 2, and the waterstop 3 is filled with polyurethane foam 4 and PVC rod 5. The upper part of the waterstop 3 is filled with asphalt-impregnated fir board 6, and asphalt felt 7 is provided between the cast surfaces of the compressive concrete panel 1 and the T-shaped concrete cover plate 2. The triangular area formed by the two sides of the T-shaped concrete cover plate 2 and the compressive concrete panel 1 is filled with flexible filler 8, and PVC rods 5 are also provided in the triangular area. The flexible filler 8 is provided with a three-component rubber plate 9 on its outer side. The three-component rubber plate 9 is fixed to the compressible concrete panel 1 and the T-shaped concrete cover plate 2 by expansion bolts 10 and steel flat steel 11 to achieve enclosure of the flexible filler 8.

[0023] The specific steps are as follows: The first step is to complete the pouring of the compressive concrete panel 1. Compressive concrete panel 1 is made of reinforced concrete, and the concrete is prepared according to the design strength requirements of the high-face rockfill dam panel. During pouring, high-frequency vibration equipment is used to ensure the compactness of the concrete, avoiding defects such as honeycomb and pitting, forming a flat and structurally stable panel foundation. After the compressive concrete panel 1 has cured to the design strength (usually more than 70% of the design strength), the pouring of the T-shaped concrete cover 2 begins. The T-shaped concrete cover 2 is also a reinforced concrete structure. Before pouring, asphalt felt 7 must be fully laid between the pouring surfaces of the compressive concrete panel 1 and the T-shaped concrete cover 2. The asphalt felt 7 must be tightly adhered to the panel surface to prevent direct bonding between the two and buffer temperature stress during the concrete hardening process. After the T-shaped concrete cover 2 is poured, it must be covered with a moisture-retaining material for standardized curing. The curing period should not be less than the design specified time to ensure its structural strength and integrity.

[0024] The second step involves constructing the structural joint filling and waterproofing system. First, a waterproofing seal 3 is installed at the bottom between the compressive concrete panel 1 and the T-shaped concrete cover 2. The waterproofing seal 3 is a W1 type copper seal; its positional deviation must be adjusted to the design tolerance during installation to ensure a tight fit between the seal 3 and the panel edge. Next, material is filled into the seal 3. First, polyurethane foam 4 is filled, ensuring it completely fills the internal gaps. Then, a PVC rod 5 is placed on top of the polyurethane foam 4. The PVC rod 5 is selected with a diameter of 25mm, a tensile strength greater than 10MPa, and a hardness greater than 65 degrees to ensure the seal 3 is fully filled and provides adequate support. Next, asphalt-impregnated fir board 6 is filled on the upper part of the waterstop 3. The standard thickness of the asphalt-impregnated fir board 6 is 10mm. If the design deformation of the dam body is large, its thickness can be adjusted according to the deformation calculation results of the dam body to ensure that the asphalt-impregnated fir board 6 can fully absorb the axial deformation of the dam. Then, the triangular area formed by the two sides of the T-shaped concrete cover plate 2 and the compressive concrete panel 1 is treated. First, flexible filler 8 is filled into the triangular area. The flexible filler 8 is a high molecular polymer flexible filler. When filling, special tools are used to compact it to avoid the formation of air bubbles or voids inside. At the same time, PVC rods 5 are placed in the triangular area to further improve the deformation resistance of the triangular area. Finally, a three-component rubber sheet 9 is laid on the outside of the flexible filler 8. The three-component rubber sheet 9 is an EPDM GB rubber composite sheet. When laying it, it must be ensured that it is free of wrinkles and damage. Then, expansion bolts 10 and steel flat bars 11 are used to fix the three-component rubber sheet 9. The expansion bolts 10 and steel flat bars 11 are made of stainless steel (or other materials with equivalent corrosion resistance). When fixing, the bolt spacing is controlled to be 200-300mm and the tightening torque meets the design requirements to ensure that the three-component rubber sheet 9 tightly surrounds the flexible filler 8 and forms a reliable seepage barrier.

[0025] During construction, quality control is required for key processes: the compressibility of the asphalt-impregnated fir board 6 needs to be sampled and tested to ensure it meets deformation absorption requirements; the welding quality of the waterstop 3 needs to pass leakage testing; the filling density of the flexible filler 8 needs to be tested using ultrasound; and the tightening force of the expansion bolts 10 needs to be checked one by one. Simultaneously, proper maintenance work should be carried out at each construction stage. Once all processes are completed and maintenance meets standards, the new type of compressive structural joint will possess excellent deformation resistance, seismic resistance, and water-stopping performance, making it suitable for the complex operating conditions of high-face rockfill dams.

[0026] It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A novel compressive structural joint for high concrete-faced rockfill dams, characterized in that, It includes a compressive concrete panel (1) and a T-shaped concrete cover plate (2), wherein the compressive concrete panel (1) and the T-shaped concrete cover plate (2) are two-stage casting structures, and the T-shaped concrete cover plate (2) is cast on top of the compressive concrete panel (1). A waterstop (3) is provided at the bottom between the compressive concrete panel (1) and the T-shaped concrete cover plate (2), and the waterstop (3) is filled with polyurethane foam (4) and PVC rod (5). The upper part of the waterstop (3) is filled with asphalt-impregnated fir board (6), and asphalt felt (7) is provided between the cast surfaces of the compressive concrete panel (1) and the T-shaped concrete cover plate (2). The triangular area formed by the two sides of the T-shaped concrete cover plate (2) and the compressive concrete panel (1) is filled with flexible filler (8), and PVC rods (5) are also provided in the triangular area. The flexible filler (8) is provided with a three-component rubber plate (9) on its outer side. The three-component rubber plate (9) is fixed to the compressible concrete panel (1) and the T-shaped concrete cover plate (2) by expansion bolts (10) and steel flat steel (11) to enclose the flexible filler (8).

2. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, Both the compressive concrete panel (1) and the T-shaped concrete cover plate (2) are reinforced concrete structures.

3. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The water stop (3) is a W1 type water stop, and the material of the water stop (3) is copper.

4. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The polyurethane foam (4) is made of polyurethane, or a polymer material with the same, similar or better properties than polyurethane.

5. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The PVC rod (5) has a diameter of 25 mm and a tensile strength of not less than 10 MPa and a hardness of not less than 65 degrees.

6. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The thickness of the asphalt-impregnated fir board (6) is 10 mm, or the thickness of the asphalt-impregnated fir board (6) can be adjusted according to the deformation requirements of the high concrete-faced rockfill dam.

7. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The flexible filler (8) is made of a polymer flexible filler.

8. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The three-component rubber sheet (9) is a EPDM GB rubber composite sheet.

9. The novel compressive structural joint for high concrete-faced rockfill dams according to claim 1, characterized in that, The expansion bolts (10) and flat steel bars (11) are made of stainless steel, or of metal materials with the same, similar or better corrosion resistance than stainless steel.

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