Earth and rockfill dam crest construction method for pouring diaphragm wall by several times

Abstract

The invention discloses an earth and rockfill dam crest construction method with diaphragm walls poured in batches, and is suitable for an earth and rockfill dam in which a wave wall is arranged on the upstream face of the top of the dam body, a retaining wall is arranged on the downstream face of the top of the dam body, a first-stage diaphragm wall is arranged in the dam body, and guide walls are arranged on the two sides of the first-stage diaphragm wall. Firstly, the top of a first-stage anti-seepage wall is trimmed into a trapezoidal structure with the distance between the two sides gradually reduced, then guide walls on the two sides are removed, then a second-stage anti-seepage wall with the top face as high as the top face of a dam body is poured in a groove above the first-stage anti-seepage wall, finally, geogrids are laid on the top face of the second-stage anti-seepage wall and the top face of a dam body soil body, a roadbed and a surface layer are built, and construction is completed. According to the anti-seepage wall, the phenomena of uneven settlement of the dam crest, cracking of the dam crest road surface and the like caused by inconsistent concrete structural strength in the dam body are eliminated, the anti-seepage effect of the anti-seepage wall is improved, the engineering quality is guaranteed, and meanwhile normal passing of personnel and vehicles on the dam crest is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of earth-rock dam construction, and in particular to an earth-rock dam crest construction method with a cut-off wall cast in stages. Background Art

[0002] When removing dangers and reinforcing earth-rock dams, in order to solve the problems of leakage and seepage stability of the dam body and dam foundation, concrete anti-seepage walls are usually used for anti-seepage treatment. Concrete anti-seepage walls can be divided into plastic concrete and reinforced concrete according to the material. Plastic concrete anti-seepage walls have certain flexibility, low strength, and good bonding with the dam body soil. They are mostly used in the anti-seepage treatment of earth dams. In order to ensure the hole slope and construction quality, guide walls are often set on both sides of the anti-seepage wall before pouring the plastic concrete anti-seepage wall. Usually, the guide wall has a depth of 1m and a width of about 0.5m. It adopts a normal concrete structure and its strength is generally not less than C20. The strength of the plastic concrete anti-seepage wall is generally not more than 5MPa. Therefore, after the anti-seepage wall is poured, there will be an uneven combination of soft and hard in the dam top structure, resulting in cracks in the dam top road surface, affecting traffic and engineering safety. However, since the outer side of the guide wall is usually an earth formwork, after pouring, it is closely bonded to the dam soil. If it is forcibly removed, it will easily affect the anti-seepage effect of the anti-seepage wall and the engineering quality of the earth-rock dam. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a method for constructing an earth-rock dam crest with an anti-settling, anti-cracking and good anti-seepage effect by pouring an anti-seepage wall in stages. Specifically, the following technical solutions can be adopted: The method for constructing the top of an earth-rock dam with a cut-off wall cast in stages of the present invention is applicable to an earth-rock dam in which a wave-breaking wall is arranged on the water-facing surface of the top of the dam body, a retaining wall is arranged on the water-receiving surface of the top of the dam body, a first-stage cut-off wall is arranged in the dam body, and guide walls are arranged on both sides of the first-stage cut-off wall, and comprises the following steps: First, the top of the first-phase anti-seepage wall is trimmed into a trapezoidal structure with gradually decreasing spacing on both sides. Then, the guide walls on both sides are removed. Then, the second-phase anti-seepage wall with the same top surface as the top surface of the dam body is poured in the groove above the first-phase anti-seepage wall. Finally, geogrids are laid on the top surface of the second-phase anti-seepage wall and the top surface of the dam body soil, and the roadbed and surface layer are built to complete the construction. The steps for removing the guide walls on both sides are as follows: S1: Use a road grooving machine to make grooves along the outer sides of the two guide walls to separate the sides of the guide walls from the dam soil; S2: Use a pneumatic pick and gas cutting equipment to cut the bottom of the downstream guide wall horizontally, and use the excavator bucket teeth to grab the top of the guide wall and push it toward the first-stage anti-seepage wall in the middle, so that the downstream guide wall can be tilted along the trapezoidal structure at the top of the first-stage anti-seepage wall to separate it from the dam soil, and then lift it out with a crane; S3, use a pneumatic pick and gas cutting equipment to cut the bottom of the upstream guide wall horizontally, and use the excavator bucket teeth to grab the top of the guide wall and push it to the first-stage anti-seepage wall in the middle, so that the upstream guide wall can be tilted along the trapezoidal structure at the top of the first-stage anti-seepage wall to achieve separation from the dam soil, and then lifted out with a crane.

[0004] The first-stage anti-seepage wall is arranged close to the upstream side of the dam body, and the first-stage anti-seepage wall is a plastic concrete wall with a thickness of 0.4-0.8m.

[0005] The guide wall is symmetrically arranged on both sides of the top of the first-phase anti-seepage wall, and the width of the single-side guide wall is 0.55~0.65m and the depth is 1m.

[0006] The second-phase anti-seepage wall is cast by plastic concrete with a compressive strength of 1.5-2.5 MPa.

[0007] The bottom surface of the second-stage anti-seepage wall is arranged at the same height as the bottom surface of the trapezoidal structure of the first-stage anti-seepage wall, and the width of the second-stage anti-seepage wall is equal to the sum of the widths of the first-stage anti-seepage wall and the guide wall.

[0008] The geogrid includes an A-type geogrid arranged above the second-phase anti-seepage wall, a B-type geogrid arranged at the top surface of the dam body soil, and a C-type geogrid arranged at the junction of the second-phase anti-seepage wall and the top surface of the dam body soil.

[0009] The A-type geogrid, the B-type geogrid and the C-type geogrid have the same height, and the hole size of the A-type geogrid is 25×25 mm, the hole size of the B-type geogrid is 50×50 mm, and the hole size of the C-type geogrid is 20×20 mm.

[0010] The roadbed and the surface layer are both arranged to be inclined downward along the water flow direction with a slope of 2%.

[0011] The surface layer includes a 120 mm thick 5% cement stabilized crushed stone layer, a 6 mm thick emulsified asphalt seal layer, a 50 mm thick AC-16 dense graded asphalt concrete mixture layer and a 30 mm thick AC-13 dense graded asphalt concrete mixture layer, which are arranged in sequence from bottom to top.

[0012] The method for constructing the top of an earth-rock dam with a cut-off wall cast in stages provided by the present invention is convenient to construct and has a stable dam structure. The method first separates the outer side surface of the guide wall from the dam body, and then dumps the guide wall onto the trapezoidal structure at the top of the first-stage cut-off wall by cutting the bottom edge and pushing down the top edge, thereby achieving lossless separation of the guide wall from the dam body. Secondly, by casting the second-stage cut-off wall in the groove at the top of the first-stage cut-off wall and laying different types of geogrids in sections on the dam top, the uneven settlement of the dam top and cracking of the dam top road surface caused by inconsistent concrete structure strength in the dam body are eliminated, thereby improving the anti-seepage effect of the cut-off wall, ensuring the quality of the project, and ensuring the normal passage of personnel and vehicles on the dam top. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the guide wall-free earth-rock dam constructed in stages according to the present invention.

[0014] Figure 2 yes Figure 1 Schematic diagram of the laying of the grid layer on the top of the middle dam.

[0015] Figure 3 yes Figure 2 Enlarged view of part A in .

[0016] Figure 4 yes Figure 3 BB cross-section diagram in.

[0017] Figure 5 It is a schematic diagram of the structure of the present invention before pouring the second phase anti-seepage wall.

[0018] Figure 6 It is a structural schematic diagram of repairing the first-stage anti-seepage wall and excavating a separation groove on the side of the guide wall according to the present invention.

[0019] Figure 7 It is a structural schematic diagram of the guide wall in the present invention being poured on top of the first-stage anti-seepage wall. DETAILED DESCRIPTION

[0020] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific construction process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0021] like Figure 1-7As shown, the earth-rock dam without guide wall with the cut-off wall cast in stages of the present invention comprises a dam body 1, a wave-breaking wall 2 is arranged on the water-facing surface of the top of the dam body 1, a retaining wall 3 is arranged on the water-receiving surface of the top of the dam body 1, and a first-stage cut-off wall 4 is arranged near the upstream side in the dam body 1, which is a plastic concrete wall with a thickness of 0.4-0.8m. The top of the first-stage cut-off wall 4 is a trapezoidal structure with gradually decreasing spacing on both sides, and a second-stage cut-off wall 5 is arranged above it. The second-stage cut-off wall 5 is cast by plastic concrete with a compressive strength of 1.5-2.5MPa, and its top surface is arranged at the same height as the top surface of the dam body 1, and its bottom surface is arranged at the same height as the bottom surface of the trapezoidal structure of the first-stage cut-off wall 4, and its width is equal to the sum of the widths of the first-stage cut-off wall 4 and the original guide wall 6. The original guide wall 6 is symmetrically arranged on both sides of the top of the first-stage cut-off wall 4, and the width of the original guide wall 6 on one side is 0.55-0.65m and the depth is 1m. A type geogrid 7 is laid on the second-phase anti-seepage wall 5, a type B geogrid 8 is laid on the top surface of the dam body 1 soil, a type C geogrid 9 is laid at the junction of the second-phase anti-seepage wall 5 and the top surface of the dam body 1 soil, and a roadbed 10 and a surface layer 11 are set on the A-type geogrid 7, the B-type geogrid 8 and the C-type geogrid 9. The heights of the above-mentioned A-type geogrid 7, the B-type geogrid 8 and the C-type geogrid 9 are equal, and they are all composed of a steel wire 71 with a diameter of 1.5 mm passing through and fixed on a 3×3 mm grid bar 72. Among them, the hole size of the A-type geogrid 7 is 25×25 mm, the hole size of the B-type geogrid 8 is 50×50 mm, and the hole size of the C-type geogrid 9 is 20×20 mm. Further, the roadbed 10 and the surface layer 11 are both set downwardly along the water flow direction with a slope of 2%. The surface layer 11 in this embodiment includes a 120 mm thick 5% cement stabilized gravel layer, a 6 mm thick emulsified asphalt seal layer, a 50 mm thick AC-16 dense graded asphalt concrete mixture layer and a 30 mm thick AC-13 dense graded asphalt concrete mixture layer, which are arranged in sequence from bottom to top.

[0022] The method for constructing the earth-rock dam crest with the cut-off wall cast in stages of the present invention comprises the following steps: The first step is to repair the top surface of the first phase anti-seepage wall 4: S1, use a small excavator with a bucket width of 30 cm to dig out the first-phase anti-seepage wall 4 inside the guide wall 6 to 10 cm above the elevation design elevation (reserving a 10 cm protective layer); S2, manually trimming the top of the first-stage cut-off wall 4 so that its top is a trapezoidal structure with gradually smaller spacing on both sides; The second step is to remove the guide walls 6 on both sides: S1, use a road grooving machine to respectively make grooves 12 along the outer sides of the two guide walls 6, the width of the groove 12 is 15 cm, and the depth of the groove 12 is determined according to the depth of the guide wall 6, generally 100 to 120 cm, so that the side of the guide wall 6 is separated from the dam soil; S2, use a pneumatic pick and gas cutting equipment to cut the bottom of the downstream guide wall 6 horizontally, and use the excavator bucket teeth to grab the top of the guide wall 6 and push it to the first-stage anti-seepage wall 4 in the middle, so that the downstream guide wall 6 is tilted along the trapezoidal structure on the top of the first-stage anti-seepage wall 4 to achieve separation from the dam soil, and then hoisted out with a crane; S3, use a pneumatic pick and gas cutting equipment to cut the bottom of the upstream guide wall 6 horizontally, and use the excavator bucket teeth to grab the top of the guide wall 6 and push it to the first-stage anti-seepage wall 4 in the middle, so that the upstream guide wall 6 is tilted along the trapezoidal structure on the top of the first-stage anti-seepage wall 4 to achieve separation from the dam soil, and then hoisted out with a crane; Preferably, a pneumatic pick can be used in conjunction with a gas cutting device to perform multiple transverse cuts on the middle of the guide wall 6 to cut off the longitudinal steel bars and divide the guide wall 6 into blocks for easy knocking down and lifting; The third step is to pour the second-phase anti-seepage wall 5 whose top surface is the same height as the top surface of the dam body 1 in the groove above the first-phase anti-seepage wall 4; The fourth step is to lay geogrids on the top surface of the second-phase anti-seepage wall 5 and the top surface of the dam body 1 soil, build the roadbed 10 and the surface layer 11, and complete the construction.

[0023] The above-mentioned method of removing the guide wall and the pouring of the anti-seepage wall can fully avoid the adverse effects on the anti-seepage performance of the dam body. Furthermore, since different types of geogrids are laid in sections on the dam top, the uneven settlement of the dam top and cracking of the dam top road surface caused by the inconsistent strength of the concrete structure in the dam body are eliminated, the anti-seepage effect of the anti-seepage wall is improved, the quality of the project is guaranteed, and the normal passage of personnel and vehicles on the dam top is guaranteed.

[0024] It should be noted that, in the description of the present invention, terms indicating orientation or positional relationships, such as "front", "rear", "left", "right", "vertical", "horizontal", "inside", "outside", etc., are based on the orientation or positional relationships shown in the drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

Claims

1. A method for constructing the top of an earth-rock dam with a cut-off wall cast in stages, which is suitable for an earth-rock dam with a wave-breaking wall on the water-facing surface of the top of the dam body, a retaining wall on the water-receiving surface of the top of the dam body, a first-stage cut-off wall in the dam body, and guide walls on both sides of the first-stage cut-off wall, characterized in that: The steps include: First, the top of the first-phase anti-seepage wall is trimmed into a trapezoidal structure with gradually decreasing spacing on both sides. Then, the guide walls on both sides are removed. Then, the second-phase anti-seepage wall with the same top surface as the top surface of the dam body is poured in the groove above the first-phase anti-seepage wall. Finally, geogrids are laid on the top surface of the second-phase anti-seepage wall and the top surface of the dam body soil, and the roadbed and surface layer are built to complete the construction. The steps for removing the guide walls on both sides are as follows: S1: Use a road grooving machine to make grooves along the outer sides of the two guide walls to separate the sides of the guide walls from the dam soil; S2: Use a pneumatic pick and gas cutting equipment to cut the bottom of the downstream guide wall horizontally, and use the excavator bucket teeth to grab the top of the guide wall and push it toward the first-stage anti-seepage wall in the middle, so that the downstream guide wall can be tilted along the trapezoidal structure at the top of the first-stage anti-seepage wall to separate it from the dam soil, and then lift it out with a crane; S3, use a pneumatic pick and gas cutting equipment to cut the bottom of the upstream guide wall horizontally, and use the excavator bucket teeth to grab the top of the guide wall and push it to the first-stage anti-seepage wall in the middle, so that the upstream guide wall can be tilted along the trapezoidal structure at the top of the first-stage anti-seepage wall to achieve separation from the dam soil, and then lifted out with a crane.

2. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The first-stage anti-seepage wall is arranged close to the upstream side of the dam body, and the first-stage anti-seepage wall is a plastic concrete wall with a thickness of 0.4-0.8m.

3. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The guide wall is symmetrically arranged on both sides of the top of the first-phase anti-seepage wall, and the width of the single-side guide wall is 0.55~0.65m and the depth is 1m.

4. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The second-phase anti-seepage wall is cast by plastic concrete with a compressive strength of 1.5-2.5 MPa.

5. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The bottom surface of the second-stage anti-seepage wall is arranged at the same height as the bottom surface of the trapezoidal structure of the first-stage anti-seepage wall, and the width of the second-stage anti-seepage wall is equal to the sum of the widths of the first-stage anti-seepage wall and the guide wall.

6. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The geogrid includes an A-type geogrid arranged above the second-phase anti-seepage wall, a B-type geogrid arranged at the top surface of the dam body soil, and a C-type geogrid arranged at the junction of the second-phase anti-seepage wall and the top surface of the dam body soil.

7. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 6, characterized in that: The A-type geogrid, the B-type geogrid and the C-type geogrid have the same height, and the hole size of the A-type geogrid is 25×25 mm, the hole size of the B-type geogrid is 50×50 mm, and the hole size of the C-type geogrid is 20×20 mm.

8. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The roadbed and the surface layer are both arranged to be inclined downward along the water flow direction with a slope of 2%.

9. The method for constructing the earth-rock dam crest with the cut-off wall cast in stages according to claim 1, characterized in that: The surface layer includes a 120 mm thick 5% cement stabilized crushed stone layer, a 6 mm thick emulsified asphalt seal layer, a 50 mm thick AC-16 dense graded asphalt concrete mixture layer and a 30 mm thick AC-13 dense graded asphalt concrete mixture layer, which are arranged in sequence from bottom to top.

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