High earth rock cofferdam anti-seepage structure for deep covering layer foundation

Abstract

The utility model discloses a deep covering layer foundation high earth rock cofferdam anti-seepage structure which comprises a concrete anti-seepage wall, curtain grouting is connected to the lower portion and the side portion of the concrete anti-seepage wall, and composite geomembrane inclined walls are arranged on toe boards on the upper portion of the concrete anti-seepage wall and the upper portion of the curtain grouting. The composite geomembrane inclined wall comprises a rock-fill layer, a supporting layer, a lower cushion layer, a lean cement mortar fixed slope, a composite geomembrane, an upper cushion layer, a geotechnical cloth inverted filter layer and a five-twisted steel wire gabion protective layer which are sequentially arranged from bottom to top. According to the cofferdam anti-seepage structure, combined anti-seepage of the composite geomembrane inclined wall, the concrete anti-seepage wall and the curtain grouting is adopted, on-site construction is facilitated, the multiplicity and safety of combined anti-seepage are utilized to the maximum extent, the situation that the whole cofferdam is unstable due to the fact that anti-seepage treatment is not in place is avoided, and the cofferdam anti-seepage structure has the advantages of being simple in structure and convenient to use. And the integrity and effectiveness of the whole anti-seepage structure of the cofferdam are ensured, the anti-seepage effect is improved, and the anti-seepage quality is

Description

Technical Field

[0001] This utility model relates to the technical field of cofferdam seepage prevention structures, specifically to a cofferdam seepage prevention structure with a deep overburden foundation and high soil and rock. Background Art

[0002] In water conservancy and hydropower projects, cofferdams are temporary water-retaining structures used in diversion works to protect the foundation pit. Their safety and stability are crucial to ensuring the smooth progress of the entire project. With the development of water conservancy and hydropower projects, the construction of earth-rock cofferdams on thick overburden layers has become a trend. However, the foundation and the cofferdam body itself formed using natural overburden layers are threatened by high water heads and large-volume rainfall. Therefore, for earth-rock cofferdams on thick overburden layers, the integrity and effectiveness of the seepage prevention structure are critical to the stability of the cofferdam body, the smooth progress of foundation pit excavation and dam filling, and the safety of life and property of downstream construction workers.

[0003] In some water conservancy and hydropower projects, the construction scope of the cofferdam seepage prevention system is a high and steep slope section, which is wide and the entire slope bedrock is exposed and easy to collapse. In addition, the water head on the water-facing side is high and the seepage prevention pressure is large. If the seepage prevention treatment is not in place, a major seepage accident is likely to occur later, which will damage the integrity and effectiveness of the entire seepage prevention system and lead to the instability of the entire cofferdam.

[0004] Therefore, it is necessary to design a technically feasible, safe, reliable, and economically reasonable deep overburden foundation high earth-rock cofferdam seepage prevention structure. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a seepage prevention structure for a high soil and rock cofferdam with a deep overburden foundation. It adopts a combined seepage prevention structure of "composite geomembrane inclined wall + concrete seepage prevention wall + curtain grouting", which can prevent the instability of the entire cofferdam due to inadequate seepage prevention treatment and ensure the integrity and effectiveness of the seepage prevention structure.

[0006] A seepage prevention structure for a high earth-rock cofferdam on a deep overburden foundation includes a concrete cutoff wall, with curtain grouting connected to the lower and side parts of the concrete cutoff wall, and a composite geomembrane inclined wall installed on the toe plate of the upper part of the concrete cutoff wall and the upper part of the curtain grouting. The composite geomembrane inclined wall includes, from bottom to top, a rockfill layer, a support layer, a lower cushion layer, a lean cement mortar slope stabilization layer, a composite geomembrane, an upper cushion layer, a geotextile filter layer, and a five-strand steel wire gabion protective layer.

[0007] A further technical solution is as follows: the rockfill layer is made of stone with a particle size of no more than 800mm and a thickness of 3m; the support layer is made of stone with a particle size of no more than 100mm and a thickness of 0.5m; the subbase layer is made of stone with a particle size of no more than 15mm and a thickness of 0.25m; and the lean cement mortar slope stabilization is made of cement and a thickness of 0.01m.

[0008] A further technical solution is as follows: the upper subbase is made of stones with a particle size of no more than 15mm and a thickness of 0.25m; the geotextile filter layer uses 500g / m² geotextile. 2 The single-layer geotextile and the five-strand steel wire gabion protective layer are made of five-strand steel wire gabions filled with stones, with a thickness of 0.5m.

[0009] A further technical solution is that the thickness of the concrete anti-seepage wall is set to 1.2m, and the bottom is embedded 1m into the bedrock.

[0010] A further technical solution is as follows: the 28-day compressive strength of the seepage barrier wall is 7.5 MPa to 10.0 MPa, the elastic modulus is 1500 MPa to 2500 MPa, and the permeability coefficient is ≤1.0 × 10⁻⁶. -7 cm / s, the density of concrete is not less than 2100 kg / m³ 3 .

[0011] A further technical solution is: the spacing between the grouting holes in the curtain grouting is set to 1.5m, the grouting holes are filled with grout, and the grouting depth extends into the top line of the relatively impermeable layer.

[0012] The beneficial effects of this utility model are:

[0013] The cofferdam seepage prevention structure of this utility model adopts a combination of "composite geomembrane inclined wall + concrete seepage prevention wall + curtain grouting" for seepage prevention. This not only facilitates on-site construction, but also maximizes the multi-layered and safe nature of the combined seepage prevention, avoiding the instability of the entire cofferdam due to inadequate seepage prevention treatment, and ensuring the integrity and effectiveness of the entire seepage prevention structure of the cofferdam, thereby improving the seepage prevention effect and guaranteeing the seepage prevention quality.

[0014] The composite geomembrane inclined wall prevents water infiltration through the composite geomembrane. The upper cushion layer, geotextile filter layer, and five-strand gabion protective layer above the composite geomembrane protect it. The upper cushion layer protects the composite geomembrane from damage by the coarse stones in the five-strand gabion protective layer. The geotextile filter layer blocks water seepage, and the five-strand gabion protective layer resists water erosion and falling rocks. Below the composite geomembrane, the lean cement mortar slope stabilization layer, lower cushion layer, support layer, and rockfill layer support the composite geomembrane. The lean cement mortar slope stabilization layer stabilizes the slope and levels the surface, making the composite geomembrane surface smooth. The support layer prevents the loss of lower cushion material. The lower cushion layer drains accumulated water and air from under the composite geomembrane and protects it. The rockfill layer accommodates the settlement deformation of the cofferdam, mitigating the degree of tearing and damage to the composite geomembrane caused by the settlement deformation of the cofferdam and rockfill.

[0015] Concrete cutoff walls can prevent seepage water flow and ensure the stability of the cofferdam. The multiple rows of grouting holes in the grouting curtain can form a continuous water-blocking curtain, further preventing water seepage. Attached Figure Description

[0016] Figure 1 This is a diagram showing the unfolded structure of the cofferdam for seepage prevention according to this utility model.

[0017] In the picture:

[0018] 1. Composite geomembrane inclined wall, 2. Concrete anti-seepage wall, 3. Curtain grouting, 4. Toe slab. DETAILED DESCRIPTION

[0019] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0020] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not 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 on the utility model.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0022] The earth-rock cofferdam composite geomembrane seepage-proof inclined wall structure in this embodiment is applied to the construction of the upstream cofferdam of the Lawa Hydropower Station. The upstream cofferdam of the Lawa Hydropower Station has a crest elevation of 2597.00m, a crest length of 187.75m, a crest width of 15.00m, and a maximum height of 60m.

[0023] like Figure 1 As shown, a seepage prevention structure for a high earth-rock cofferdam on a deep overburden foundation includes a concrete cutoff wall 2, with curtain grouting 3 connecting the lower and side parts of the concrete cutoff wall 2, and a composite geomembrane inclined wall 1 installed on the upper part of the concrete cutoff wall 2 and the toe plate 4 above the curtain grouting. The composite geomembrane inclined wall 1 includes, from bottom to top, a rockfill layer, a support layer, a lower cushion layer, a lean cement mortar slope stabilization layer, a composite geomembrane, an upper cushion layer, a geotextile filter layer, and a five-strand steel wire gabion protective layer.

[0024] Specifically, the rockfill layer is constructed using stones with a particle size no greater than 800mm and a thickness of 3m; the support layer is constructed using stones with a particle size no greater than 100mm and a thickness of 0.5m; the lower cushion layer is constructed using stones with a particle size no greater than 15mm and a thickness of 0.25m; and the lean cement mortar slope stabilization layer is constructed using cement and a thickness of 0.01m. The upper cushion layer is constructed using stones with a particle size no greater than 15mm and a thickness of 0.25m. The geotextile filter layer uses 500g / m² geotextile. 2 The single-layer geotextile and the five-strand steel wire gabion protective layer are made of five-strand steel wire gabions filled with stones, with a thickness of 0.5m.

[0025] The concrete cutoff wall 2 has a thickness of 1.2m, is embedded 1m into the bedrock at the bottom, and has an axial length of 129m. The cutoff wall has a 28-day compressive strength of 7.5MPa~10.0MPa, an elastic modulus of 1500MPa~2500MPa, and a permeability coefficient ≤1.0×10⁻⁶. - 7 cm / s, the density of concrete is not less than 2100 kg / m³ 3 .

[0026] The lower part and sides of the concrete cutoff wall 2 are connected to the curtain grouting 3. The grouting hole spacing is set at 1.5m. Grout is injected into the grouting holes, and multiple rows of grouting holes form a continuous water-blocking curtain. The grouting depth extends to the top line of the relatively impermeable layer (the permeability of the upstream cofferdam q<5Lu, and the permeability of the downstream cofferdam q<10Lu). Preferably, the pilot hole is set 5.0m below the top line of the relatively impermeable layer.

[0027] Based on the above-mentioned ideal embodiment of the present invention, and in accordance with the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the content of the specification, but must be determined according to the scope of the claims.

Claims

1. A high earth-rock cofferdam anti-seepage structure for a thick overburden foundation, characterized in that: It includes a concrete cut-off wall, the lower and side parts of the concrete cut-off wall are connected to curtain grouting, and a composite geomembrane inclined wall is arranged on the upper part of the concrete cut-off wall and the toe plate of the upper part of the curtain grouting. The composite geomembrane inclined wall includes a rockfill layer, a supporting layer, a lower cushion layer, a lean cement mortar slope consolidation layer, a composite geomembrane, an upper cushion layer, a geotextile filter layer, and a five-twisted steel wire gabion protective layer arranged in sequence from bottom to top.

2. The anti-seepage structure of high earth-rock cofferdam in deep overburden foundation according to claim 1, characterized in that: The rockfill layer is paved with stones with a particle size not exceeding 800mm and a thickness of 3m, the supporting layer is paved with stones with a particle size not exceeding 100mm and a thickness of 0.5m, the sub-base layer is paved with stones with a particle size not exceeding 15mm and a thickness of 0.25m, and the lean cement mortar slope consolidation is paved with cement and a thickness of 0.01m.

3. The anti-seepage structure of high earth-rock cofferdam in deep overburden foundation according to claim 2, characterized in that: The upper cushion layer is paved with stones with a particle size not greater than 15mm and a thickness of 0.25m. The geotextile filter layer is 500g / m 2 Single-layer geotextile, five-twisted steel wire gabion protective layer uses five-twisted steel wire gabion filled with stones, and the thickness is set to 0.5m.

4. The anti-seepage structure of high earth-rock cofferdam in deep overburden foundation according to claim 1, characterized in that: The thickness of the concrete anti-seepage wall is set to 1.2m, and the bottom is embedded in the bedrock by 1m.

5. The anti-seepage structure of high earth-rock cofferdam in deep overburden foundation according to claim 4, characterized in that: The 28-day compressive strength of the anti-seepage wall is 7.5MPa~10.0MPa, the elastic modulus is 1500MPa~2500Mpa, and the permeability coefficient is ≤1.0×10 -7 cm / s, the density of concrete is not less than 2100kg / m 3 .

6. The anti-seepage structure of high earth-rock cofferdam in deep overburden foundation according to claim 1, characterized in that: The grouting hole spacing of curtain grouting is set to 1.5m, grouting holes are filled with slurry, and the grouting depth reaches the top line of the relatively impermeable layer.

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