Geomembrane and bank slope combination structure applied to geomembrane core wall cofferdam and construction method thereof

Abstract

This invention discloses a geomembrane-slope bonding structure and its construction method for a geomembrane core wall cofferdam. The structure includes a dam body, a seepage barrier wall disposed inside the dam body, and a geomembrane. The seepage barrier wall extends into the bedrock at the bottom of the riverbed, and a seepage barrier curtain is installed on the seepage barrier wall. The geomembrane is placed on the seepage barrier curtain. This invention not only eliminates the need for a cover plate structure, simplifying construction procedures, shortening the construction period, and improving on-site construction efficiency, but also ensures the seepage prevention performance of the composite geomembrane at the junction with the dam shoulder by setting a filling layer, ensuring the overall seepage prevention effect of the cofferdam meets the standards. Simultaneously, it solves the problems of cumbersome construction and delayed construction period of existing bonding structures, achieving a dual improvement in construction convenience and seepage prevention reliability. It meets the seepage prevention requirements of cofferdam projects, accelerates construction progress, reduces construction costs, and ensures the long-term stable operation of the cofferdam.

Description

Technical Field

[0001] This invention belongs to the field of hydropower and water conservancy engineering technology, and in particular relates to a geomembrane and bank slope combination structure applied to geomembrane core wall cofferdam and its construction method. Background Technology

[0002] In hydropower and water conservancy projects, composite geomembranes have become the mainstream seepage control material for earth-rock cofferdams due to their technical advantages such as low cost, convenient construction, and excellent seepage control performance. Their application is particularly widespread in areas where natural seepage control materials such as clay are scarce. Based on the placement of the composite geomembrane within the cofferdam structure, earth-rock cofferdam seepage control methods are mainly divided into two categories: geomembrane core wall seepage control and geomembrane inclined wall seepage control. The geomembrane core wall seepage control scheme places the composite geomembrane in the core seepage control area in the middle of the cofferdam.

[0003] like Figure 5 As shown, in conventionally designed bank slope structures, after the base concrete is poured, holes need to be drilled in the base concrete according to the design spacing. Then, one end of the composite geomembrane is wrapped around a steel plate twice and fixed to the base concrete with anchor bolts. Next, the formwork is erected and the cover slab concrete is poured to complete the sealed connection between the geomembrane and the base. This process of laying the bedding material, laying the geomembrane, and pouring the cover slab concrete is repeated until the designed weir crest elevation is reached. In this structural design, after the cover slab concrete is poured, the connection between the cover slab concrete and the base concrete needs to be sealed and protected with the cover slab concrete to prevent leakage at the connection due to structural deformation later, thus ensuring the stability of the entire seepage prevention system. However, in the current construction process, the connection is not effectively sealed and protected after the cover slab concrete is poured, leading to potential leakage at the connection and affecting the overall seepage prevention effect. This is a key point that needs to be optimized and improved in the future. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a geomembrane-slope bonding structure for geomembrane core wall cofferdams and its construction method.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a geomembrane and bank slope combination structure for a geomembrane core wall cofferdam, comprising a dam body, a seepage barrier wall disposed inside the dam body, and a geomembrane. The seepage barrier wall extends into the bedrock at the bottom of the riverbed, and a seepage barrier curtain is disposed on the seepage barrier wall, with the geomembrane disposed on the seepage barrier curtain.

[0007] Preferably, the geomembrane is connected to the impermeable wall via a base, and the geomembrane is arranged in a Z-shape.

[0008] Preferably, the end of the geomembrane is connected to a fixing plate, which is fastened to the base by anchor bolts and nuts, and a washer is provided between the fixing plate and the nut.

[0009] Preferably, the fixing plate is disposed in a geomembrane embedding groove opened on the base, and a filling layer is disposed in the geomembrane embedding groove.

[0010] A construction method for a geomembrane-slope integrated structure applied to a geomembrane core wall cofferdam includes the following steps: S1: After the riverbed is closed, weir construction is carried out, and the soil on the weir is simultaneously shaped and compacted to form a seepage prevention wall construction platform; S2: The anti-seepage wall is constructed by relying on the anti-seepage wall construction platform. First, trenches are made on the weir body, then the trenches are cleaned and concrete is poured to obtain the anti-seepage wall. After the anti-seepage wall is constructed, the anti-seepage curtain under the wall is constructed. S3: After the anti-seepage curtain under the wall is completed, the upper weir body of the anti-seepage wall is filled, the curtain grouting on both banks is carried out and the geomembrane is laid. The base is prepared on the weir shoulders on both banks, and the geomembrane inlay groove is set on the base. The geomembrane inlay groove is obtained by pouring concrete. Then the weir shoulder curtain grouting is completed. The geomembrane is then connected to the base through the fixing plate and fastened to the base through anchor bolts and nuts. S4: Compacted stone is filled on the seepage barrier wall. On the upstream side of the geomembrane embedding groove, transition material and cushion material are sequentially filled on the compacted stone from the upstream side to the downstream side to obtain the transition layer and the cushion layer. The transition layer is set on both sides of the cushion layer. Both the transition layer and the cushion layer are set in layers. S5: Lay the geomembrane along the interface between the cushion layer and the geomembrane inlay groove. The geomembrane is connected to the geomembrane inlay groove through the fixing plate and is fastened to the geomembrane inlay groove through anchor bolts and nuts. S6: Set a filling layer inside the geomembrane embedding groove; S7: On the downstream side of the geomembrane embedding groove, fill the cushion material and transition material on the compacted stone slag from the upstream side to the downstream side to obtain the cushion layer and transition layer. S8: Repeat S4-S6, repeating the construction procedures of layered filling of the bedding layer and transition layer on the dam body and laying of the geomembrane, until the geomembrane is laid as a whole and the full-section filling of the dam body reaches the design elevation.

[0011] Preferably, the thickness of each transition layer and cushion layer in S4 is 1 / 2 of the thickness of the crushed stone.

[0012] Preferably, the slope ratios at the junctions of the transition layer and the cushion layer, and at the junctions of the cushion layer and the geomembrane in S4 are both 1:1-2.

[0013] Preferably, the slope ratio at the junction of the cushion layer and the transition layer in S7 is 1:1-2.

[0014] Preferably, the geomembrane embedding groove is Z-shaped, and a fixing plate, anchor bolt and nut are provided at each bend in the geomembrane embedding groove to fix the geomembrane.

[0015] Preferably, the filling layer is epoxy mortar, the components of which include water-based epoxy main agent, curing agent and sand, and the mass ratio of water-based epoxy main agent, curing agent and sand is 1:0.5:3-7.

[0016] The beneficial effects of this invention are as follows: This invention simultaneously forms the geomembrane embedding groove during the pouring of the base concrete, eliminating the traditional concrete cover plate process. The composite geomembrane is anchored to the base concrete using steel plates and high-strength chemical anchors, and the embedding groove is filled and sealed with epoxy mortar. This not only simplifies the construction process, shortens the construction period, and improves on-site construction efficiency, but also ensures the seepage prevention performance of the composite geomembrane at the junction with the weir shoulder, ensuring that the overall seepage prevention effect of the cofferdam meets the standards. It also solves the problems of cumbersome construction and delayed construction period of existing joint structures, achieving a dual improvement in construction convenience and seepage prevention reliability. This not only meets the seepage prevention requirements of cofferdam projects but also accelerates construction progress, reduces construction costs, and ensures the long-term stable operation of the cofferdam. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the geomembrane embedding groove of the present invention; Figure 2 yes Figure 1 BB cross-section; Figure 3 This is a schematic diagram of the structure of the seepage-proof wall of the present invention; Figure 4 This is a schematic diagram of the structure of the present invention; Figure 5 This is a schematic diagram of a conventionally designed bank slope structure; In the diagram: 1-Dam body, 2-Impact wall, 3-Geomembrane, 4-Impact curtain, 5-Filling layer, 6-Base, 7-Fixing plate, 8-Anchor bolt, 9-Nut, 10-Impact wall construction platform, 11-Geomembrane embedding groove, 12-Transition layer, 13-Subbase layer. Detailed Implementation

[0018] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0019] Example: like Figures 1 to 4 As shown, a geomembrane-slope combined structure for a geomembrane core wall cofferdam includes a dam body 1, a seepage barrier wall 2 and a geomembrane 3 disposed inside the dam body 1. The seepage barrier wall 2 extends into the bedrock at the bottom of the riverbed, and a seepage barrier curtain 4 is disposed on the seepage barrier wall 2 and the dam shoulder. The geomembrane 3 is disposed on the seepage barrier curtain 4.

[0020] The geomembrane 3 is connected to the weir shoulder seepage prevention curtain 4 via the base 6, and the geomembrane 3 is arranged in a Z-shape.

[0021] The end of the geomembrane 3 is connected to the fixing plate 7, and the fixing plate 7 is connected and fastened to the base 6 by anchor bolts 8 and nuts 9. A gasket is provided between the fixing plate 7 and the nuts 9.

[0022] The fixing plate 7 is set in the geomembrane embedding groove 13 opened on the base 6, and the geomembrane embedding groove 13 is filled with a filling layer 5.

[0023] A construction method for a geomembrane-slope integrated structure applied to a geomembrane core wall cofferdam includes the following steps: S1: After the riverbed is closed, the construction of weir 1 is carried out, and the soil on weir 1 is simultaneously shaped and compacted to form the anti-seepage wall construction platform 12. S2: The anti-seepage wall 2 is constructed based on the anti-seepage wall construction platform 12. First, a trench with a length of 6-8m is made on the weir body 1. Then, the trench is cleaned and concrete is poured to obtain the anti-seepage wall 2. The thickness of the anti-seepage wall 2 is 0.6-1.2m. The bottom of the anti-seepage wall 2 extends into the bedrock by 0.5-1.0m. After the anti-seepage wall 2 is constructed, the anti-seepage curtain under the wall is constructed. S3: After the anti-seepage curtain under the wall is completed, the upper weir body filling of the anti-seepage wall, the curtain grouting on both banks and the laying of geomembrane will be carried out. Base 6 will be prepared on the weir shoulders on both banks, and geomembrane inlay groove 13 will be set on the base 6. The geomembrane inlay groove 13 will be obtained by concrete pouring. Then the weir shoulder curtain grouting 4 will be completed. Then the geomembrane 3 will be connected to the base 6 through the fixing plate 7 and connected and fastened to the base 6 through the anchor bolt 8 and nut 9. S4: Compacted stone is filled on the seepage barrier wall 2, and a filling area for cushion material and transition material is reserved. The slope ratio at the junction of soil, stone and transition material is its self-stabilizing slope ratio of 1:1.6. On the upstream side of the geomembrane embedding groove 13, transition material and cushion material are filled on the compacted stone from the upstream side to the downstream side to obtain transition layer 14 and cushion layer 15. Transition layer 14 is set on both sides of cushion layer 15. Transition layer 14 and cushion layer 15 are set in layers in the vertical direction. The thickness of each layer of transition layer 14 and cushion layer 15 is 1 / 2 of the thickness of compacted stone, about 40~60cm. The slope ratio at the junction of transition layer 14 and cushion layer 15 and the junction of cushion layer 15 and geomembrane 3 is 1:1.6. S5: Geomembrane 3 is laid along the interface between the cushion layer 15 and the geomembrane embedding groove 13. The geomembrane 3 is connected to the geomembrane embedding groove 13 through the fixing plate 7, and is connected and fastened to the geomembrane embedding groove 13 through anchor bolts 8 and nuts 9 to ensure the sealing of the geomembrane end anchor and the stability of the connection structure. The spacing between adjacent anchor bolts 8 is 0.5~1.0m. S6: A filling layer 5 is set in the geomembrane embedding groove 13; S7: On the downstream side of the geomembrane embedding groove 13, fill the cushion material and transition material on the crushed stone from the upstream side to the downstream side to obtain the cushion layer 15 and the transition layer 14. The slope ratio at the junction of the cushion layer 15 and the transition layer 14 is 1:1.6. S8: Repeat S4-S6, repeating the construction procedures of layered filling of the upper cushion layer 15 and transition layer 14 of the dam body 1 and laying of the geomembrane 3, until the geomembrane 3 is laid as a whole and the full-section filling of the dam body 1 reaches the design elevation.

[0024] Of the methods for constructing the anti-seepage wall, constructing the anti-seepage curtain under the wall, filling the upper dam body of the anti-seepage wall, grouting the curtains on both banks, and laying the geomembrane, only the steps described in this embodiment are applicable; the rest are mature existing technologies.

[0025] The geomembrane embedding groove 13 is Z-shaped, and a fixing plate 7, anchor bolt 8 and nut 9 are provided at each bend in the geomembrane embedding groove 13 to fix the geomembrane 3.

[0026] The thickness of the filling layer 5 is not less than 20cm. The filling layer 5 is epoxy mortar, and its components include water-based epoxy main agent, curing agent and sand. The mass ratio of water-based epoxy main agent, curing agent and sand is 1:0.5:3-7. The water-based epoxy main agent includes modified water-based epoxy resin and emulsifier. The curing agent is a water-based amine curing agent. The sand is dried quartz sand (moisture content ≤0.5%).

[0027] This application uses a filling layer 5 to seal the geomembrane embedding groove 13.

Claims

1. A geomembrane-slope bonding structure for use in geomembrane core wall cofferdams, characterized in that: It includes a weir (1), a seepage barrier (2) set inside the weir (1) and a geomembrane (3). The seepage barrier (2) extends into the bedrock at the bottom of the riverbed. A seepage barrier curtain (4) is set on the seepage barrier (2), and the geomembrane (3) is set on the seepage barrier curtain (4).

2. The geomembrane-slope bonding structure for a geomembrane core wall cofferdam as described in claim 1, characterized in that: The geomembrane (3) is connected to the seepage barrier wall (2) via a base (6), and the geomembrane (3) is arranged in a Z-shape.

3. The geomembrane-slope bonding structure for a geomembrane core wall cofferdam as described in claim 2, characterized in that: The end of the geomembrane (3) is connected to a fixing plate (7), which is fastened to the base (6) by anchor bolts (8) and nuts (9). A gasket is provided between the fixing plate (7) and the nuts (9).

4. The geomembrane-slope bonding structure for a geomembrane core wall cofferdam as described in claim 3, characterized in that: The fixing plate (7) is set in the geomembrane embedding groove (13) opened on the base (6), and the geomembrane embedding groove (13) is filled with a filling layer (5).

5. A construction method for a geomembrane-slope integrated structure applied to a geomembrane core wall cofferdam as described in claim 4, characterized in that, Includes the following steps: S1: After the riverbed is closed, the weir (1) is constructed, and the soil on the weir (1) is simultaneously shaped and compacted to form a seepage prevention wall construction platform (12). S2: The anti-seepage wall (2) is constructed by relying on the anti-seepage wall construction platform (12). First, a groove is made on the weir body (1), then the groove is cleaned and concrete is poured to obtain the anti-seepage wall (2). After the anti-seepage wall (2) is constructed, the anti-seepage curtain under the wall is constructed. S3: After the anti-seepage curtain under the wall is completed, the upper dam body filling, curtain grouting on both sides and geomembrane laying are carried out. Base (6) is prepared on the dam shoulders on both sides, and geomembrane inlay groove (13) is set on the base (6). The geomembrane inlay groove (13) is obtained by concrete pouring. Then the dam shoulder curtain grouting (4) is completed. Then the geomembrane (3) is connected to the base (13) through the fixing plate (7) and connected and tightened to the base (13) through the anchor bolt (8) and nut (9). S4: Compacted stone is filled on the seepage barrier wall (2). On the upstream side of the geomembrane embedding groove (13), transition material and cushion material are filled on the compacted stone from the upstream side to the downstream side to obtain the transition layer (14) and the cushion layer (15). The transition layer (14) is set on both sides of the cushion layer (15). Both the transition layer (14) and the cushion layer (15) are set in layers. S5: Lay geomembrane (3) along the interface between the cushion layer (15) and the geomembrane inlay groove (13). The geomembrane (3) is connected to the geomembrane inlay groove (13) through the fixing plate (7) and is connected and fastened to the geomembrane inlay groove (13) through the anchor bolt (8) and nut (9). S6: Set a filling layer (5) in the geomembrane embedding groove (13); S7: In the direction downstream of the geomembrane embedding groove (13), fill the cushion material and transition material on the crushed stone from the upstream side to the downstream side to obtain the cushion layer (15) and the transition layer (14). S8: Cycle S4-S6, repeat the construction procedures of layered filling of the upper cushion layer (15) and transition layer (14) of the weir body (1) and laying of the geomembrane (3) until the geomembrane (3) is laid as a whole and the full-section filling of the weir body (1) reaches the design elevation.

6. The construction method of the geomembrane and bank slope combination structure applied to geomembrane core wall cofferdam as described in claim 5, characterized in that: The thickness of each transition layer (14) and cushion layer (15) in S4 is 1 / 2 of the thickness of the crushed stone.

7. The construction method for a geomembrane-slope combined structure applied to a geomembrane core wall cofferdam as described in claim 5, characterized in that: The slope ratios at the junctions of the transition layer (14) and the cushion layer (15) and the cushion layer (15) and the geomembrane (3) in S4 are both 1:1-2.

8. The construction method for a geomembrane-slope integrated structure applied to a geomembrane core wall cofferdam as described in claim 5, characterized in that: The slope ratio at the junction of the cushion layer (15) and the transition layer (14) in S7 is 1:1-2.

9. A construction method for a geomembrane-slope integrated structure applied to a geomembrane core wall cofferdam as described in claim 5, characterized in that: The geomembrane inlay groove (13) is arranged in a Z shape. A fixing plate (7), anchor bolt (8) and nut (9) are provided at each bend in the geomembrane inlay groove (13) to fix the geomembrane (3).

10. A construction method for a geomembrane-slope integrated structure applied to a geomembrane core wall cofferdam as described in claim 5, characterized in that: The filling layer (5) is epoxy mortar, the components of which include water-based epoxy main agent, curing agent and sand, and the mass ratio of water-based epoxy main agent, curing agent and sand is 1:0.5:3-7.

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