A dam diversion tunnel plugging anti-seepage structure and construction method

Abstract

The present invention discloses an anti-seepage structure and construction method for a dam diversion tunnel plug, comprising a diversion tunnel, a waterstop A, and a waterstop B. The cross section of the waterstop A is T-shaped, and the waterstop A is composed of a steel plate A and a steel plate B. The steel plate A and the waterstop B are pre-buried on the inner wall of the diversion tunnel, and the outer periphery of the steel plate B is welded to the inner wall of the steel plate A. The inner edge of the steel plate B is provided with a bending portion, and the bending portion is bent 40° to 60° in the direction of water flow. The present invention pre-buries the steel plate A during the construction of the diversion tunnel plug, and welds the steel plate B to the steel plate A at the same time, thereby improving the anti-seepage effect of the waterstop A. The waterstop A and the waterstop B are used in combination to improve the anti-seepage effect of the plug, and after the plug concrete is constructed, the top arch of the plug section is backfilled and grouted to further enhance the overall compactness of the plug, prevent leakage, and ensure the safe and stable operation of the dam.

Description

Technical Field

[0001] The invention belongs to the field of hydropower engineering construction, and in particular relates to a dam diversion tunnel plugging anti-seepage structure and a construction method. Background Art

[0002] The diversion tunnel is used to divert and divert the river water under construction after the cofferdams are built upstream and downstream of the hydropower project to ensure that the dam project is constructed on dry land. The diversion tunnel is a temporary structure. After the water diversion structures and flood discharge structures of the hydropower project are completed, it will lose its function and need to be sealed. The sealing of the diversion tunnel marks the beginning of water storage in the hydropower project and is a key control condition for reservoir water storage. For example, a Chinese patent with application number 201910707131.6 discloses a method for safely plugging a diversion tunnel under high head and poor geological conditions in a hydropower project. The existing diversion tunnel plugging and anti-seepage generally adopts the method of pre-embedding annular copper sheet waterstop during the diversion tunnel lining and backfilling grouting. The general anti-seepage effect of the prior art has certain risks. The dam construction period is relatively long, generally 2-3 years or even longer. Before that, the diversion tunnel needs to be in operation for at least 3 years. Due to the long-term flow of the diversion tunnel and the dam site in a mountain canyon river, the proportion of suspended sediment is large, which will damage the pre-embedded annular copper sheet waterstop. If the annular copper sheet waterstop is fully wrapped, it will not be easy to chisel out in the later construction. In order to ensure the safety of the dam's later operation, the diversion tunnel plug is particularly important. Therefore, a dam diversion tunnel plugging and anti-seepage structure and construction method are needed to ensure the anti-seepage of the diversion tunnel plug, avoid seepage and leakage, and ensure the safe and stable operation of the dam. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a dam diversion tunnel plugging anti-seepage structure and construction method, which can solve the problem of poor anti-seepage effect of the prior art.

[0004] The present invention is achieved through the following technical solutions.

[0005] The present invention provides a dam diversion tunnel plugging and anti-seepage structure, comprising a diversion tunnel, a waterstop A and a waterstop B. The cross-section of the waterstop A is T-shaped. The waterstop A is composed of a steel plate A and a steel plate B. The steel plate A and the waterstop B are pre-buried on the inner wall of the diversion tunnel. The outer periphery of the steel plate B is welded to the inner wall of the steel plate A. The inner edge of the steel plate B is provided with a bending portion, which is bent 40° to 60° in the direction of water flow.

[0006] A plug is provided in the diversion tunnel, which is made of poured concrete. One end of the steel plate B and the waterstop B is embedded in the diversion tunnel, and the other end of the steel plate B and the waterstop B is embedded in the plug.

[0007] The waterstop B and waterstop A are arranged in sequence in the plugging section, and the distance between the waterstop A and the waterstop B is 90 mm to 120 mm.

[0008] The steel plates A and B are made of stainless steel galvanized steel plates, and the waterstop B is made of water-swellable rubber.

[0009] The width of the steel plate A and the steel plate B are both 30mm to 40mm, and the thickness is 2mm to 3mm.

[0010] A grouting gallery is provided in the middle of the plug, and the grouting gallery is arranged along the center line of the plug.

[0011] A construction method for a dam diversion tunnel plugging and anti-seepage structure, characterized in that it comprises the following steps:

[0012] S1, before the plugging construction, the installation groove is excavated and the steel plate A and the water stop belt B are embedded in the inner wall of the diversion tunnel;

[0013] S2, after bending and shaping the steel plate B, the steel plate B is welded to the steel plate A. After welding, non-destructive testing is performed. If the weld is unqualified, rework is performed until all welds meet the requirements;

[0014] S3, grouting holes are drilled at the top of the diversion tunnel. The grouting holes are evenly distributed along the diversion tunnel and penetrate more than 10 cm into the bedrock. After the grouting holes are drilled, grouting pipes and exhaust pipes are installed. Both the grouting pipes and exhaust pipes extend into the grouting holes.

[0015] S4, pouring plugging concrete;

[0016] S5, after the pouring of the plug concrete is completed, the concrete shrinkage is likely to form a cavity between the top arch of the diversion tunnel, and the upper part of the plug is backfilled and grouted through the grouting pipe;

[0017] S6: After the internal temperature of the plug concrete cools down to 15°C, overlap curtain grouting is carried out from bottom to top in the dam grouting flat tunnel.

[0018] In step S3, the diameter of the grouting hole is 50mm to 60mm, the grouting pipe consists of a main pipe and a branch pipe, the diameter of the grouting main pipe is 25mm to 30mm, the diameter of the grouting branch pipe is 18mm to 20mm, the diameter of the exhaust pipe is 20mm to 25mm, and the interval between the grouting holes is 2m to 3m.

[0019] In S5, the grouting pressure is 0.3 MPa to 0.5 MPa, and the water-cement ratio of the grouting slurry is gradually increased from 2:1 to 0.5:1.

[0020] The beneficial effects of the present invention are: by pre-embedding steel plate A during the construction of the diversion tunnel plug, and welding steel plate B to steel plate A at the same time, the anti-seepage effect of waterstop A is improved, and the anti-seepage effect of the plug is improved by using waterstop A in conjunction with waterstop B. After the construction of the plug concrete is completed, the top arch part of the plug section is backfilled and grouted to further enhance the overall compactness of the plug, prevent leakage, and ensure the safe and stable operation of the dam. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the installation position of waterstop A and waterstop B;

[0023] Figure 3 It is a structural schematic diagram of water stop A;

[0024] In the figure: 1- diversion tunnel, 2- waterstop A, 3- waterstop B, 4- steel plate A, 5- steel plate B, 7- plug, 8- grouting gallery, 9- bending part. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0026] like Figure 1 , Figure 2 , Figure 3 As shown, a dam diversion tunnel plugging and anti-seepage structure includes a diversion tunnel 1, a waterstop A2, and a waterstop B3. The cross-section of the waterstop A2 is T-shaped. The waterstop A2 is composed of a steel plate A4 and a steel plate B5. The steel plate A4 and the waterstop B3 are pre-buried on the inner wall of the diversion tunnel 1. The outer periphery of the steel plate B5 is welded to the inner wall of the steel plate A4. The inner edge of the steel plate B5 is provided with a bending portion 9, and the bending portion 9 is bent 40° to 60° in the direction of incoming and outgoing water.

[0027] Before the construction of the plug of the diversion tunnel 1, an installation groove is excavated, the steel plate A4 and the waterstop B3 are pre-buried on the inner wall of the diversion tunnel, and the steel plate B5 is welded to the steel plate A4, so as to prevent the steel plate B5 from improving the water-stopping effect of the waterstop. When the plug 7 is poured, the waterstop B3 and the waterstop A2 are both embedded in the plug 7, thereby forming a barrier between the plug 7 and the diversion tunnel 1, preventing water from leaking from the gap between the plug 7 and the diversion tunnel 1 under the action of pressure, thereby improving the sealing effect of the plug.

[0028] A plug 7 is provided in the diversion tunnel 1. The plug 7 is made of concrete pouring. One end of the steel plate B5 and the waterstop B3 are embedded in the diversion tunnel 1, and the other end of the steel plate B5 and the waterstop B3 are embedded in the plug 7. The plug 7 is used to seal the diversion tunnel 1. When the plug 7 is poured, the concrete fills the steel plate B5, the waterstop B3 and the water retaining sill 6. After the plug 7 is formed, the steel plate B5, the waterstop B3 and the water retaining sill 6 are embedded in the plug 7, thereby forming a barrier between the plug 7 and the diversion tunnel 1 to prevent water from leaking from the gap between the plug 7 and the diversion tunnel 1 under the action of pressure, thereby improving the compactness of the plug.

[0029] The waterstop B3 and waterstop A2 are arranged in sequence in the plug section, and the spacing between waterstop A2 and waterstop B3 is 90mm to 120mm. Waterstop B3 and waterstop A2 are arranged at intervals, so that after the steel plate B5 and waterstop B3 are embedded in the plug 7, they can form a barrier to avoid affecting each other.

[0030] The material of the steel plate A4 and the steel plate B5 is stainless steel galvanized steel plate, and the material of the waterstop B3 is water-swellable rubber. The stainless steel galvanized steel plate has high strength and is not easy to corrode, ensuring the long-term stability of the plug. The water-swellable rubber model is preferably BW-Ⅱ type. The water-swellable rubber can increase in volume after being immersed in water, filling the gap between the waterstop B3 and the concrete, improving the water-stopping performance, and preventing water leakage.

[0031] The width of the steel plates A4 and B5 is 30mm to 40mm, and the thickness is 2mm to 3mm, so that the steel plates A4 and B5 can be embedded to a sufficient depth to avoid displacement during blocking, and the steel plates A4 and B5 have a certain strength to withstand the effect of water pressure.

[0032] A grouting gallery 8 is provided in the middle of the plug 7, and the grouting gallery 8 is arranged along the center line of the plug 7. After the plug concrete construction is completed, the anti-seepage effect of the plug concrete can be checked through the grouting gallery 8 during the plug operation period. If there is no leakage, it will be sealed.

[0033] A construction method for a dam diversion tunnel plugging and anti-seepage structure, characterized in that it comprises the following steps:

[0034] S1, before the plugging construction, the installation groove is excavated and the steel plate A and the water stop belt B are embedded in the inner wall of the diversion tunnel;

[0035] S2, after bending and shaping the steel plate B, the steel plate B is welded to the steel plate A. After welding, non-destructive testing is performed. If the weld is unqualified, rework is performed until all welds meet the requirements to ensure that the steel plate B and the steel plate A are firmly connected;

[0036] S3, grouting holes are drilled at the top of the diversion tunnel. The grouting holes are evenly distributed along the direction of the diversion tunnel, and the grouting holes penetrate more than 10 cm into the bedrock. After the grouting holes are drilled, grouting pipes and exhaust pipes are installed. The grouting pipes and exhaust pipes are both extended into the grouting holes. The grouting pipes and exhaust pipes are installed on the upper part of the diversion tunnel, which is convenient for grouting from the upper part of the diversion tunnel through the grouting pipes in the later stage, and the air is discharged through the exhaust pipe to ensure that the concrete can smoothly enter the grouting position;

[0037] S4, pouring the plugging concrete, according to the current pouring process, pouring the plugging concrete;

[0038] S5. After the pouring of the plug concrete is completed, the concrete shrinkage is easy to form a cavity between it and the top arch of the diversion tunnel. The upper part of the plug is backfilled and grouted through the grouting pipe. Generally, after the last bin of the plug concrete is poured, the concrete shrinkage is easy to form a cavity between it and the top lining concrete. Backfill grouting is adopted for this part to ensure the compactness of the cavity on the top of the plug concrete. When backfilling and grouting, the grouting hole is drilled to the upper part of the top and penetrated 10cm into the bedrock to ensure the effect of backfill grouting of the cavity between the plug concrete and the top arch. Even if the slurry shrinks, the gap is still in the upper part of the grouting hole, so that the main structure of the plug is full and full.

[0039] S6. After the internal temperature of the plug concrete cools down to 15°C, overlap curtain grouting is carried out from bottom to top in the dam grouting flat hole to improve the water-stopping ability of the plug. The water-cement ratio of the grouting slurry gradually changes from thin to thick, and the water-cement ratios are 3:1, 2:1, 1:1, 0.8:1, and 0.5:1, respectively.

[0040] In step S3, the diameter of the grouting hole is 50mm to 60mm, the grouting pipe consists of a main pipe and a branch pipe, the diameter of the grouting main pipe is 25mm to 30mm, the diameter of the grouting branch pipe is 18mm to 20mm, the diameter of the exhaust pipe is 20mm to 25mm, and the interval between the grouting holes is 2m to 3m to ensure that each grouting hole can be grouted smoothly, and the air in the grouting hole can be discharged through the exhaust pipe to ensure that the grouting hole can be filled.

[0041] In S5, the grouting pressure is 0.3MPa to 0.5MPa, and the water-cement ratio of the grouting slurry is gradually increased from 2:1 to 0.5:1. The thinner grouting slurry has better permeability and can quickly fill the gaps to avoid the appearance of voids. After using the thin slurry, the water-cement ratio of the grouting slurry is increased, and a thicker grouting is used to complete the adjustment of the remaining space, so that after the plug is poured, its upper part is full to avoid the appearance of gaps and water leakage.

Claims

1. A dam diversion tunnel plugging and anti-seepage structure, characterized in that: The invention comprises a diversion tunnel (1), a waterstop strip A (2), and a waterstop strip B (3); the cross section of the waterstop strip A (2) is T-shaped, and the waterstop strip A (2) is composed of a steel plate A (4) and a steel plate B (5); the steel plate A (4) and the waterstop strip B (3) are pre-buried on the inner wall of the diversion tunnel (1), and the outer periphery of the steel plate B (5) is welded to the inner wall of the steel plate A (4); the inner edge of the steel plate B (5) is provided with a bending portion (9), and the bending portion (9) is bent by 40° to 60° in the direction of the incoming and outgoing water.

2. A dam diversion tunnel plugging and anti-seepage structure according to claim 1, characterized in that: The diversion tunnel (1) is provided with a plug (7), which is made of poured concrete; one end of the steel plate B (5) and the water stop belt B (3) are embedded in the diversion tunnel (1), and the other end of the steel plate B (5) and the water stop belt B (3) are embedded in the plug (7).

3. A dam diversion tunnel plugging and anti-seepage structure according to claim 1, characterized in that: The waterstop strip B (3) and the waterstop strip A (2) are arranged in sequence in the plug section, and the distance between the waterstop strip A (2) and the waterstop strip B (3) is 90 mm to 120 mm.

4. A dam diversion tunnel plugging and anti-seepage structure according to claim 1, characterized in that: The steel plates A (4) and B (5) are made of stainless steel galvanized steel plates, and the water stop strip B (3) is made of water-swellable rubber.

5. A dam diversion tunnel plugging and anti-seepage structure according to claim 1, characterized in that: The steel plates A (4) and B (5) have a width of 30 mm to 40 mm and a thickness of 2 mm to 3 mm.

6. A dam diversion tunnel plugging and anti-seepage structure according to claim 2, characterized in that: A grouting gallery (8) is provided in the middle of the plug (7), and the grouting gallery (8) is arranged along the center line of the plug (7).

7. A construction method for a dam diversion tunnel plugging and anti-seepage structure according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, before the plugging construction, the installation groove is excavated and the steel plate A and the water stop belt B are embedded in the inner wall of the diversion tunnel; S2, after bending and shaping the steel plate B, the steel plate B is welded to the steel plate A. After welding, non-destructive testing is performed. If the weld is unqualified, rework is performed until all welds meet the requirements; S3, grouting holes are drilled at the top of the diversion tunnel. The grouting holes are evenly distributed along the diversion tunnel and penetrate more than 10 cm into the bedrock. After the grouting holes are drilled, grouting pipes and exhaust pipes are installed. Both the grouting pipes and exhaust pipes extend into the grouting holes. S4, pouring plugging concrete; S5, after the pouring of the plug concrete is completed, the concrete shrinkage is likely to form a cavity between the top arch of the diversion tunnel, and the upper part of the plug is backfilled and grouted through the grouting pipe; S6: After the internal temperature of the plug concrete cools down to 15°C, overlap curtain grouting is carried out from bottom to top in the dam grouting flat tunnel.

8. A construction method for a dam diversion tunnel plugging and anti-seepage structure as claimed in claim 7, characterized in that: In step S3, the diameter of the grouting hole is 50mm to 60mm, the grouting pipe consists of a main pipe and a branch pipe, the diameter of the grouting main pipe is 25mm to 30mm, the diameter of the grouting branch pipe is 18mm to 20mm, the diameter of the exhaust pipe is 20mm to 25mm, and the interval between the grouting holes is 2m to 3m.

9. The construction method of a dam diversion tunnel plugging and anti-seepage structure according to claim 7, characterized in that: In S5, the grouting pressure is 0.3 MPa to 0.5 MPa, and the water-cement ratio of the grouting slurry is gradually increased from 2:1 to 0.5:1.

Images