A method for optimizing the mechanical behavior of a face dam cutoff wall and the safety performance of a cutoff joint

Abstract

The present application belongs to the technical field of earth-rock dam construction, and provides a method for optimizing the mechanical behavior of a face dam cutoff wall and the safety performance of a cutoff joint, which comprises the following steps: 1) on the basis of a traditional cutoff wall, an auxiliary cutoff wall is added in the horizontal direction behind the traditional cutoff wall, and the structure of the traditional cutoff wall is used as the main cutoff wall; 2) a water-stop copper sheet with waterproof properties is arranged on the top of the left bank and the right bank of the main cutoff wall, so as to resist the risk of leakage induced by tensile cracking on the top of the wall; and 3) inverted trapezoidal asphalt concrete is arranged under the concrete connecting plate and the concrete toe plate, so as to enhance the anti-permeation safety margin of the cutoff joint. The auxiliary cutoff wall proposed in the present application bears the frictional drag effect of foundation deformation on the wall body, effectively reducing the risk of tensile cracking on the top of the main cutoff wall; at the same time, the design of the water-stop copper sheet, the clay blanket and the asphalt concrete can achieve multi-directional enhancement of the anti-permeation performance of the cutoff joint, and significantly improve the safety performance of the face dam anti-permeation system for controlling seepage and preventing leakage on a deep overburden layer.

Description

Technical Field

[0001] This invention belongs to the field of earth-rock dam construction technology, and relates to a method for optimizing the mechanical properties of the anti-seepage wall and the safety performance of the anti-seepage joint of a panel dam. Background Technology

[0002] Concrete panels, toe slabs, connecting slabs, and cutoff walls, as well as joint sealing between various components, are currently the main design type for rockfill dams with thick overburden.

[0003] In recent years, the geological conditions of the dam site area have become increasingly complex, and the depth of the overburden layer has repeatedly reached new highs, posing new challenges to the project construction. Among them, the problems of high stress in the anti-seepage wall and leakage risk induced by water-stop deformation have become increasingly prominent, and have become technical bottlenecks restricting the construction of dams on the overburden layer. These are key problems that engineering researchers are focusing on.

[0004] Numerical analysis of a rockfill dam with a thick overburden layer reveals that when the tensile stress in a localized area at the top of the cutoff walls on both banks exceeds the ultimate tensile strength of the concrete, there is a risk of tensile cracking leading to leakage. Furthermore, if the deformation of the joint between the connecting plate and the cutoff wall is significant, exceeding the allowable limit of the existing waterproofing structure, there is also a risk of tearing of the waterproofing seal, triggering leakage. Optimizing the design to enhance the seepage control and leakage prevention performance of the cutoff system is crucial for ensuring the safe operation of the project and is of great significance for improving my country's high dam construction technology. Summary of the Invention

[0005] This invention aims to provide a method for optimizing the mechanical properties of the cutoff wall and the safety performance of the cutoff joint in a panel dam. By using a 'higher in the front and lower in the back' double-row cutoff wall arrangement, combined with three layers of seepage prevention optimization measures, the comprehensive seepage control and leakage prevention capabilities of the panel dam seepage prevention system are improved from multiple dimensions.

[0006] An optimized design method for the mechanical properties of the anti-seepage wall and the safety performance of the anti-seepage joint of a panel dam is proposed. The improvements made to the traditional anti-seepage wall structure design are as follows: (1) An auxiliary anti-seepage wall is added behind the traditional anti-seepage wall in the horizontal direction, and the traditional anti-seepage wall structure serves as the main anti-seepage wall. (2) Waterproof copper sheets with waterproof properties are installed in the weak areas on the top of the left and right banks of the main anti-seepage wall to resist the risk of leakage induced by tensile cracking at the top of the wall. (3) Inverted trapezoidal asphalt concrete is installed under the concrete connecting plate and the concrete toe plate to enhance the anti-seepage safety margin of the anti-seepage joint.

[0007] Specifically, the steps include the following:

[0008] 1) A 'high in the front and low in the back' double-row anti-seepage wall arrangement is proposed, in which the main anti-seepage wall is higher than the auxiliary anti-seepage wall. The auxiliary anti-seepage wall bears the frictional drag effect of the overburden on the wall, thereby improving the vertical stress behavior of the main anti-seepage wall. The main and auxiliary anti-seepage walls have the same thickness. A mud skin is provided between the main and auxiliary anti-seepage walls. The design and arrangement of the connecting plates, toe plates, face plates and the water-stopping design between them in the anti-seepage system are the same as the traditional design.

[0009] 2) Water-stop copper plates are installed at the top weak areas on the left and right banks of the main seepage barrier wall. The installation height is not less than the sum of the thickness of the concrete connection plate and the thickness of the asphalt concrete at the bottom. This design resists the risk of leakage caused by tensile cracking at the top of the wall.

[0010] 3) An inverted trapezoidal asphalt concrete is set at the bottom of the concrete connection plate and the concrete toe plate, and a trapezoidal asphalt concrete partition is set behind the concrete toe plate. The above design enhances the seepage resistance safety margin of the seepage prevention joint.

[0011] The dimensional design requirements for each key component are as follows:

[0012] 1) The bottom of the main cutoff wall is flush with the bottom of the auxiliary cutoff wall, and the top is higher than the top of the auxiliary cutoff wall. h 3, of which h 3 is greater than the sum of the thickness of the concrete connecting plate and the thickness of the asphalt concrete at its bottom.

[0013] 2) The depth of the aforementioned water-stopping copper sheet is h 2, value less than h 3, but not less than the sum of the thickness of the concrete connecting plate and the thickness of the asphalt concrete at its bottom; the lengths of the water-stop copper strips along the dam axis are respectively l 7 and l 8. The design length should not be less than the stress distribution range exceeding the design value of the tensile strength of concrete.

[0014] 3) The top surface of the concrete connecting plate is flush with the top surface of the main anti-seepage wall; the total thickness of the concrete connecting plate and the asphalt concrete below it is less than [amount missing]. h 3. The upper and lower base lengths of the asphalt concrete are... l 4 and l 5. Thickness h 5. The slope of the inclined side is 1:m2; the design length should not be less than 1.2 times the sum of the lengths of the concrete connecting slab and the concrete toe slab, the height should not be less than the thickness of the concrete connecting slab, and the slope should not be less than 1.0.

[0015] 4) The trapezoidal asphalt concrete section behind the concrete toe slab has upper and lower base lengths of... l 3 and l 6. Thick h4. The slope of the inclined side is 1:m1; the design length should not be less than the length of the concrete toe slab, the height should not be less than the thickness of the concrete toe slab, and the slope should not be less than 1.0.

[0016] The auxiliary seepage barrier wall of this invention bears the direct impact of foundation deformation on the seepage barrier wall, effectively reducing the risk of tensile cracking at the top of the main seepage barrier wall; at the same time, the controlled design of the water-stop copper sheet and asphalt concrete can achieve bidirectional enhancement of the seepage resistance of the seepage joint, significantly improving the safety performance of the seepage control and leakage prevention system of the panel dam on the thick overburden layer.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] (1) The auxiliary seepage barrier wall bears the direct effect of foundation deformation on the seepage barrier wall, effectively reducing the risk of tensile cracking at the top of the main seepage barrier wall;

[0019] (2) At the same time, the layout design of the water-stop copper sheet and asphalt concrete can achieve bidirectional enhancement of the seepage resistance of the seepage joint, which significantly improves the safety performance of the seepage control and leakage prevention system of the deep overburden dam. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the optimized design scheme for the seepage prevention system of the rockfill dam with a thick overburden layer in this invention;

[0021] Figure 2 This is a schematic diagram of the cross-sectional layout of the anti-seepage wall along the dam axis;

[0022] Numbering in the diagram: 1-Concrete panel; 2-Water-stop copper sheet; 3-Concrete connecting plate; 4-Concrete toe plate; 5-Asphalt concrete; 6-Covering layer; 7-Main anti-seepage wall; 8-Auxiliary anti-seepage wall; 9-Mud skin sandwiched between anti-seepage walls; 10-Rockfill; 11-Main anti-seepage wall (view from upstream and downstream directions); 12-Weak zone A; 13-Weak zone B. Detailed Implementation

[0023] The relevant designs of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the following description of the present invention and its embodiments is not restrictive, and the actual embodiments are not limited thereto. In short, if those skilled in the art, inspired by this description, design similar structural methods and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

[0024] This example provides a method for optimizing the mechanical properties of the cutoff wall and the safety performance of the cutoff joint in a panel dam. The details are as follows:

[0025] like Figure 1As shown, this invention improves the overall seepage control and leakage prevention capabilities of the panel dam seepage prevention system from multiple dimensions by using a double-row, parallel arrangement of anti-seepage walls and combining two layers of seepage prevention optimization measures. The design and construction steps of each part are described in detail below.

[0026] 1) A parallel arrangement of two rows of anti-seepage walls with a higher front and lower back is proposed (the main anti-seepage wall is higher than the auxiliary anti-seepage wall). h 3) The auxiliary cutoff wall bears the frictional drag of the overburden layer on the wall, thereby improving the vertical stress behavior of the main cutoff wall. The thickness of both the main and auxiliary cutoff walls is [missing information]. d ;

[0027] 2) The tops of both banks of the main anti-seepage wall are set with lengths of respectively l 5 and l 6. Deeply concerned h The 2-inch copper waterproofing sheet is used to resist the risk of leakage caused by tensile cracks at the top of the wall;

[0028] 3) An inverted trapezoidal asphalt concrete section is provided at the bottom of the concrete connecting slab and the concrete toe slab, with upper and lower base lengths of [missing information]. l 4 and l 5. Thickness h 5. The slope of the inclined side is 1:m2; at the same time, a trapezoidal asphalt concrete section is set behind the concrete toe slab, with the upper and lower base lengths being... l 3 and l 6. Thick h 4. The slope of the inclined side is 1:m1. The above design enhances the seepage resistance safety margin of the anti-seepage joint.

[0029] The following study uses a specific engineering project as an example to illustrate the specific parameters of the measures proposed in this invention. The dam is a rockfill dam with a thick overburden layer and a maximum height of 150m and a crest width of 14m. The upstream slope is 1:1.6, and the downstream slope is 1:1.8. The thickness of the upstream concrete panel varies from top to bottom at a ratio of 0.4 + 0.0035H, where H is the dam height. The downstream slope uses a 1m thick dry-laid stone revetment. A suspended cutoff wall structure is used, with a depth of 190m and a thickness of 1.4m, with 1m thick sections embedded in bedrock on both banks. The top of the cutoff wall is connected to the toe slab via two 4m long connecting plates. The specific operation process is described below:

[0030] 1) A double-row, parallel arrangement of cutoff walls is proposed, with the main and auxiliary cutoff walls adopting a "higher in the front, lower in the back" design, and both walls having a thickness of [missing information]. d =1.4m, the main seepage barrier wall is higher than the auxiliary seepage barrier wall h 1 = 10m, with a thin layer of mud sandwiched between the two walls;

[0031] 2) Based on the numerical model analysis results, the tops of both banks of the main anti-seepage wall are set with lengths of respectively... l 5=330m and l6 = 280m, depth is h A 20m thick copper water-stop sheet is used to resist the risk of leakage caused by tensile cracking at the top of the wall;

[0032] 3) An inverted trapezoidal asphalt concrete section is provided at the bottom of the concrete connecting slab and the concrete toe slab, with upper and lower base lengths of [missing information]. l 4=16m and l 5 = 18m, thickness is h 5 = 1.4m, with a slope of 1:1.4; simultaneously, a trapezoidal asphalt concrete section is set behind the toe slab, with upper and lower base lengths of... l 3 = 2.4m and l 6 = 6m, thickness is h 4 = 1.8m, and the slope of the hypotenuse is 1:1.

[0033] The above design enhances the seepage resistance safety margin of the anti-seepage joint.

[0034] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for optimizing the mechanical behavior of a face dam diaphragm wall and the safety performance of the diaphragm joint, characterized in that, The optimized design method adopts a 'higher in the front, lower in the back' double-row anti-seepage wall arrangement, combined with multiple anti-seepage optimization measures, to improve the comprehensive seepage control and leakage prevention capabilities of the panel dam anti-seepage system; the specific design is as follows: (1) The double-row anti-seepage wall is arranged in a 'high in front and low in back' manner. That is, on the basis of the traditional anti-seepage wall, an auxiliary anti-seepage wall (8) is added behind it in the horizontal direction. Here, the traditional anti-seepage wall structure serves as the main anti-seepage wall (7). The main anti-seepage wall (7) is higher than the auxiliary anti-seepage wall (8). The bottom of the main anti-seepage wall (7) is flush with the auxiliary anti-seepage wall (8), and the top is higher than the auxiliary anti-seepage wall (8). A mud cake (9) is provided between the main anti-seepage wall (7) and the auxiliary anti-seepage wall (8). (2) Waterproof copper sheets (2) with waterproof properties are installed in the weak areas at the top of the left and right banks of the main anti-seepage wall (7). The height of the sheet is not less than the sum of the thickness of the concrete connecting plate (3) and the thickness of the asphalt concrete (5) at its bottom, in order to resist the risk of leakage caused by tensile cracking at the top of the wall. (3) An inverted trapezoidal asphalt concrete (5) is set at the bottom of the concrete connecting plate (3) and the concrete toe plate (4) to enhance the seepage resistance safety margin of the seepage prevention joint; at the same time, a trapezoidal asphalt concrete partition is set behind the concrete toe plate (4). The auxiliary anti-seepage wall (8) bears the direct effect of foundation deformation on the anti-seepage wall body, reducing the risk of tensile cracking at the top of the main anti-seepage wall; at the same time, the layout design of the water-stop copper sheet (2) and asphalt concrete (5) can achieve bidirectional enhancement of the anti-seepage performance of the anti-seepage joint, and improve the safety performance of the anti-seepage control and leakage prevention system of the panel dam on the thick overburden layer.

2. The method according to claim 1, wherein The dimensional design requirements for each key component are as follows: 1) The main cutoff wall (7) is higher than the auxiliary cutoff wall (8). The bottom of the main cutoff wall (7) is flush with the auxiliary cutoff wall (8), and the top is higher than the auxiliary cutoff wall (8). h 3, of which h 3 is greater than the sum of the thickness of the concrete connecting plate (3) and the thickness of the bottom asphalt concrete (5); the thickness of the main seepage barrier (7) and the auxiliary seepage barrier (8) are the same; 2) The depth of the water-stopping copper sheet (2) is h 2, value less than h 3, but not less than the sum of the thickness of the concrete connecting plate (3) and the thickness of the bottom asphalt concrete (5); the design length of the waterstop copper strip should not be less than the stress distribution range exceeding the design value of the tensile strength of the concrete; 3) The top surface of the concrete connecting plate (3) is flush with the top surface of the main seepage barrier wall (7); the total thickness of the concrete connecting plate (3) and the asphalt concrete (5) below it is less than h 3; The slope of the asphalt concrete (5) is 1:m2, its design length should not be less than 1.2 times the sum of the lengths of the concrete connecting plate (3) and the concrete toe plate (4), its height should not be less than the thickness of the concrete connecting plate (3), and its slope should not be less than 1.

0. 4) The trapezoidal asphalt concrete partition behind the concrete toe slab (4) has a slope of 1:m1. The design length of the asphalt concrete partition should not be less than the length of the concrete toe slab (4), the height should not be less than the thickness of the concrete toe slab (4), and the slope should not be less than 1.0.

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