A connection structure between the core wall and the bottom concrete foundation

Abstract

The present invention relates to the technical field of water conservancy and hydropower engineering, and particularly relates to a connection structure between a core wall and its bottom concrete base. It includes a core wall and several concrete bases fixedly connected to the bottom of the core wall. The joint surface between the concrete base and the core wall is an arc surface, and the arc surface has the same radius and chord length at any position in the axial direction of the core wall, which can avoid the change of the shape of the concrete base with the change of the thickness of the asphalt core wall. A water stop system is provided in the core wall, its bottom concrete base and the concrete structure joints of the base, which can improve the anti-seepage reliability between the core wall and the concrete base, the structure joints, and the joint surface between the concrete base and the lower foundation. This structure design is simple, convenient for construction, and has good reliability, and can be applied to the connection between asphalt concrete core walls and lower concrete bases under various different conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and hydropower engineering, and particularly relates to a connection structure between a core wall and a bottom concrete pedestal. Background Art

[0002] In water conservancy and hydropower engineering, asphalt concrete core wall rockfill dams have good anti-seepage and deformation adaptation performance, can adapt to large uneven settlements of the foundation and the dam body, have low requirements for the geological conditions of the dam foundation, and are increasingly widely used. For example, in many water conservancy and hydropower projects such as Yele Hydropower Station in Sichuan Province, China, Lalo Hydropower Station in Tibet, and Kalot Hydropower Station in Pakistan, the main dams of these projects all adopt asphalt concrete core wall rockfill dams.

[0003] To ensure the integrity and reliability of the dam body anti-seepage system and provide an operation platform and overburden for foundation grouting, the bottom of the asphalt concrete core wall is generally connected to the dam foundation by setting a concrete pedestal. As two materials with quite different properties, the connection between the core wall and the bottom concrete pedestal is one of the key technologies in the design of asphalt concrete core wall dams.

[0004] Currently, in water conservancy and hydropower engineering, two structural forms, namely planar connection and arc connection, are usually adopted (such as Figure 1 ). The planar connection structure is simple to construct, but when it bears a large upstream and downstream water head difference during the operation period, large relative displacements are likely to occur between the asphalt concrete core wall and the concrete pedestal, resulting in leakage easily occurring at the joint surface between the two. When an arc connection structure is adopted between the concrete pedestal and the upper asphalt concrete core wall, under the action of vertical pressure, a radial extrusion effect is generated on the contact surface between the asphalt concrete core wall and the concrete pedestal, which can reduce the upstream and downstream dislocation between the core wall and the concrete pedestal and improve the reliability of the anti-seepage system.

[0005] However, the thickness of the asphalt concrete core wall usually increases with the increase of the upstream reservoir water head in the vertical direction, and at the positions of the two banks' slopes, when the dam height decreases, the thickness of the asphalt concrete core wall decreases accordingly. To adapt to this change, in existing projects, the arc surface in contact between the concrete pedestal and the asphalt concrete core wall usually combines structural forms with variable radius and variable chord length, and the shape of the concrete pedestal and the joint part is a space special-shaped structure, which is complex in design, inconvenient in construction, and difficult to guarantee the quality. Summary of the Invention

[0006] The purpose of the present invention is to address the deficiencies of the prior art and provide a connection structure between a core wall and a bottom concrete pedestal, which can avoid the change of the shape of the concrete pedestal with the change of the thickness of the asphalt core wall on the premise of ensuring reliability, has a simple design, is convenient for construction, and can be applicable to the connection between asphalt concrete core walls and lower concrete pedestals under various different conditions.

[0007] The technical solution of the present invention is as follows: It includes a core wall and several concrete bases fixedly connected to the bottom of the core wall. The several concrete bases are distributed along the axis direction of the core wall, and a structural joint is provided between adjacent concrete bases. The joint surface between the concrete base and the core wall is an arc surface, and the arc surface has the same radius R and the same chord length N at any position in the axis direction of the core wall.

[0008] Preferably, the radius R of the joint surface is set based on the height and thickness of the core wall.

[0009] Preferably, R≥(0.004·△ + 0.8) / sin(θ / 2), where △ is the height of the core wall and θ is the central angle related to the thickness of the core wall.

[0010] Preferably, the chord length N of the joint surface = 2H·n + t, where H is the maximum height of the enlarged footing at the bottom of the core wall, n is the slope ratio of the enlarged footing in the horizontal direction to the vertical direction, and t is the maximum thickness at the joint of the core wall and the enlarged footing.

[0011] Preferably, a first waterstop is provided along the axis direction of the joint between the concrete base and the core wall. A waterstop strip is provided respectively upstream and downstream of the first waterstop in the structural joint. A second waterstop is provided between the upstream and downstream waterstop strips, and the upper end of the second waterstop is connected to the first waterstop.

[0012] Preferably, a concrete waterstop base is provided at the central position of the bottom of the concrete base, and the bottom of the concrete waterstop base is fixed to the bedrock through anchor bolts.

[0013] Preferably, the bottoms of the waterstop strip and the second waterstop both extend into the concrete waterstop base.

[0014] Preferably, the waterstop strip is a BW type water-swelling waterstop strip, and the waterstop strip is in interference fit with the structural joint.

[0015] Preferably, both ends of the second waterstop along the axis direction of the core wall are embedded and fixed in the concrete bases on both sides of the structural joint.

[0016] Preferably, an asphalt mastic layer is provided at the joint surface between the enlarged footing at the bottom of the core wall and the concrete base.

[0017] The beneficial effects of the present invention are as follows: The arc surface has the same radius and the same chord length at any position in the axis direction of the core wall, avoiding the change of the shape of the concrete base with the change of the thickness of the asphalt core wall. The design is simple and convenient for construction, and it can be applied to the connection between asphalt concrete core walls and lower concrete bases under various different conditions. At the same time, it ensures that L A1 ≥L A2, in this way, the base arc surface is always larger than the arc surface at the bottom of the core wall, which can ensure the same reliability as before the improvement. An asphalt mastic layer is provided at the joint surface between the enlarged foot at the bottom of the core wall and the concrete base, increasing the connection performance and anti-seepage performance between the asphalt concrete core wall and the concrete base. By adopting the first water stop belt and the second water stop belt of this solution, cooperating with the upstream and downstream water stop strips to form an anti-seepage system, and embedding a concrete water stop base at the bottom, the anti-seepage reliability between the asphalt concrete core wall and the concrete base, the structural joint, and the joint surface between the concrete base and the lower foundation is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. is a comparative schematic diagram of the planar connection and arc connection forms of the present invention;

[0019] Figure 2 FIG. is a top planar projection view of the concrete base of the present invention;

[0020] Figure 3 is Figure 2 sectional view taken along line A-A of

[0021] Figure 4 is Figure 3 sectional view taken along line B-B of

[0022] Figure 5 is Figure 4 enlarged schematic view of part C of

[0023] Figure 6 is a partial three-dimensional structural schematic view of the top connection of the first water stop belt and the second water stop belt.

[0024] In the figures: 1 - concrete base; 2 - core wall; 3 - enlarged foot; 4 - asphalt mastic; 5 - concrete water stop base; 6 - anchor bolt; 7 - water stop strip; 8 - second water stop belt; 9 - first water stop belt; 10 - structural joint. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, which are convenient for clearly understanding the present invention, but they do not constitute a limitation to the present invention.

[0026] As Figure 2 , 3 shown, a connection structure between a core wall and a bottom concrete base includes a core wall 2 and several concrete bases 1 connected thereto. The several concrete bases 1 are distributed along the axis direction of the core wall 2, and a structural joint 10 is provided between adjacent concrete bases 1, and an asphalt fir board or a high-density polyethylene closed-cell foam board is filled in the joint.

[0027] As Figure 4As shown in the figure, a first waterstop 9 is provided along the axis direction of the core wall 2 at the center position of the joint between the concrete base 1 and the core wall 2. Waterstop strips 7 are respectively provided upstream and downstream of the first waterstop 9 within the structural joint 10. A second waterstop 8 is provided between the upstream and downstream waterstop strips 7, and the upper end of the second waterstop 8 is connected to the first waterstop 9. A concrete waterstop base 5 is provided at the center position of the bottom of the concrete base 1, and the bottom of the concrete waterstop base 5 is fixed to the bedrock through anchor bolts 6. The bottoms of the waterstop strips 7 and the second waterstop 8 both extend into the concrete waterstop base 5.

[0028] As Figure 5 shown, the waterstop strip 7 is a BW type water-swelling waterstop strip. The waterstop strip 7 includes two sections. One section is arranged below the enlarged footing 3, and its length direction is adapted to the arc surface of the enlarged footing. The other section is vertically arranged on one side of the second waterstop 8, and the bottom of the vertically arranged waterstop strip is embedded in the concrete waterstop base 5 to realize the fixation of the waterstop strip 7. The waterstop strip 7 is in interference fit with the structural joint 10. After the waterstop strip 7 swells when encountering water, it can seal the upstream side of the structural joint, enhance the reliability of the anti-seepage system, and can play a role in grouting and plugging leaks, which is beneficial to increasing the grouting pressure of the surface rock mass and improving the grouting reliability. A gap can be provided between the waterstop strip 7 and the second waterstop 8, or they can be in contact, but no connection is provided.

[0029] Both the first waterstop 9 and the second waterstop 8 are made of copper waterstops. Among them, both ends of the second waterstop 8 along the axis direction of the core wall 2 are embedded and fixed in the concrete base 1 on both sides of the structural joint 10. As Figure 6 shown, a T-shaped structure connection is adopted between the top of the second waterstop 8 and the first waterstop 9, and this T-shaped structure connection form belongs to the conventional connection form between waterstops in this field.

[0030] The core wall 2 is connected to the lower concrete base 1 through an enlarged footing 3. The maximum height of the enlarged footing 3 is H, and the slope ratios on both sides are 1:n (vertical: horizontal). A layer of bituminous mastic 4 is applied to the joint surface between the enlarged footing 3 and the concrete base 1. This bituminous mastic 4 is a 2 cm thick sandy bituminous mastic, which is used to enhance the bonding performance of the joint surface.

[0031] The joint surface between the concrete base 1 and the core wall 2 is an arc surface, and the arc surface has the same radius R and chord length N at any position along the axis direction of the core wall 2. The chord length N is not less than the maximum length in the flow direction of the contact part between the asphalt concrete and the concrete base.

[0032] The arc radius R of the upper surface of the concrete base 1 can take a certain value according to the height and thickness of the core wall. R≥(0.004·△ + 0.8) / sin(θ / 2), and generally a fixed value convenient for construction is taken according to the calculation results. Here, △ is the height of the core wall, and θ is the central angle related to the thickness of the core wall, usually 30°. The chord length N of the bottom arc surface of the enlarged footing 3 (this arc surface is the joint surface between the concrete base 1 and the enlarged footing 3) is N = 2H·n + t, where H is the maximum height of the enlarged footing 3 at the bottom of the core wall 2, and t is the maximum thickness at the joint of the core wall 2 and the enlarged footing 3. The chord length of the upper arc surface of the concrete base 1 is L, and its value only needs to satisfy L≥N. Based on L and N, the arc length of the upper arc surface of the concrete base 1 and the arc length of the bottom arc surface of the enlarged footing 3

[0033] The above are only embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval of the application.

Claims

1. A connecting structure between a core wall and a bottom concrete pedestal, comprising a core wall (2) and a plurality of concrete pedestals (1) fixedly connected to the bottom of the core wall (2). The plurality of concrete pedestals (1) are distributed along the axis direction of the core wall (2), and a structural joint (10) is provided between adjacent concrete pedestals (1). Characterized in that: The joint surface between the concrete pedestal (1) and the core wall (2) is an arc surface, and the arc surface has the same radius R and the same chord length N at any position along the axis direction of the core wall (2). A first waterstop (9) is provided along the axis direction of the core wall (2) at the joint between the concrete pedestal (1) and the core wall (2). A waterstop strip (7) is provided upstream and downstream of the first waterstop (9) within the structural joint (10). A second waterstop (8) is provided between the upstream and downstream waterstop strips (7), and the upper end of the second waterstop (8) is connected to the first waterstop (9). Both ends of the second waterstop (8) extending along the axis direction of the core wall (2) are embedded in the concrete pedestals (1) on both sides of the structural joint (10).

2. The connecting structure between a core wall and a bottom concrete pedestal according to claim 1, Characterized in that: The radius R of the joint surface is set based on the height and thickness of the core wall (2).

3. The connecting structure between a core wall and a bottom concrete pedestal according to claim 1, Characterized in that: The radius R ≥ (0.004·△ + 0.8) / sin(θ / 2), where △ is the height of the core wall, and θ is the central angle related to the thickness of the core wall.

4. The connecting structure between a core wall and a bottom concrete pedestal according to claim 1, Characterized in that: The chord length N of the joint surface = 2H·n + t, where H is the maximum height of the enlarged base (3) at the bottom of the core wall (2), n is the slope ratio of the enlarged base (3) in the horizontal and vertical directions, and t is the maximum thickness at the joint between the core wall (2) and the enlarged base (3).

5. The connecting structure between a core wall and a bottom concrete pedestal according to claim 1, Characterized in that: A concrete waterstop pedestal (5) is provided at the center position of the bottom of the concrete pedestal (1), and the bottom of the concrete waterstop pedestal (5) is fixed to the bedrock through anchor bolts (6).

6. The connecting structure between a core wall and a bottom concrete pedestal according to claim 5, Characterized in that: The bottoms of the waterstop strip (7) and the second waterstop (8) both extend into the concrete waterstop pedestal (5).

7. The connecting structure between a core wall and a bottom concrete pedestal according to claim 1, Characterized in that: The waterstop strip (7) is a BW type water-swelling waterstop strip, and the waterstop strip (7) is in interference fit with the structural joint (10).

8. The connecting structure between a core wall and a bottom concrete pedestal according to claim 1, Characterized in that: An asphalt mastic layer (4) is provided at the joint surface between the enlarged base (3) at the bottom of the core wall (2) and the concrete pedestal (1).

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