Underwater repair method for concrete face dam leakage site

Abstract

The present application relates to the technical field of hydraulic engineering repair, in particular to a concrete face dam leakage site underwater repair method, which comprises the following steps: S1, chiseling the damaged panel; S2, positioning the leakage site, installing a flow baffle on the panel around the leakage site, and isolating a pouring chamber on the panel by the flow baffle; S3, pouring the plugging material to the leakage site through a conduit, the conduit is inserted into the pouring chamber during pouring, and the flow baffle is used to prevent the impact of water flow on the plugging material; the present application optimizes the formwork structure, limits the pouring of epoxy concrete by forming the formwork together with the water permeable net rack and the flow baffle, and adopts a step-by-step installation method. On the one hand, the flow baffle is used to reduce the influence of water flow on the plugging material during the plugging operation, thereby improving the plugging operation efficiency; on the other hand, only one water permeable net rack needs to be installed to form the formwork during the pouring of epoxy concrete.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering repair technology, and more specifically, to an underwater repair method for leakage parts of concrete-faced dams. Background Technology

[0002] Due to their advantages such as strong adaptability, rapid construction, good seismic performance, and convenient maintenance, rockfill dams with concrete panels are widely used in modern hydropower projects. As the core water-retaining structure of a hydropower station, it mainly undertakes the task of intercepting and regulating upstream water flow, transforming natural runoff into usable hydropower resources through coordination with flood discharge and power generation facilities. The stability of the dam is not only related to the power generation efficiency and peak-shaving capacity of the power station, but also directly related to the flood control safety of downstream areas. Therefore, its structural stability and long-term durability are key to ensuring the continuous and safe operation of the hydropower station.

[0003] Currently, a large number of concrete-faced rockfill dams have been built both domestically and internationally, and their overall operation is good. However, in actual operation, the concrete panels are prone to problems such as cracks and compression damage, which can lead to leakage and affect the normal use of the dam.

[0004] The current standard repair procedure for the leakage problem of rockfill dams with concrete panels is as follows: first, cut and remove the damaged panels, then seal the leakage points, then install the formwork and pour new concrete panels, remove the formwork after the concrete has solidified, and finally install the water-stop bolts and perform water-stop treatment on the joints.

[0005] However, in actual repair work, since hydropower station reservoirs often lack the capacity to be emptied, the leaking parts may be underwater, necessitating underwater construction. Existing repair methods face the challenge of prolonged underwater work for construction personnel, primarily in two aspects: Sealing materials are easily washed away by water flow: During underwater sealing, the water flow in the reservoir can affect the stability of the sealing materials, resulting in unsatisfactory sealing effects.

[0006] Underwater drilling is difficult: because underwater pouring requires the use of high-strength C35 epoxy concrete, which has high hardness, it brings great difficulties to the drilling work for subsequent installation of water-stop bolts and prolongs the construction time.

[0007] Furthermore, such repair work is typically carried out in winter because power generation is lower at this time, creating a window for construction. However, the low underwater temperatures and long working hours in winter also increase the safety risks for underwater workers. Summary of the Invention

[0008] The purpose of this invention is to provide an underwater repair method for leakage points in concrete panel dams. By optimizing the template structure and using a permeable mesh frame and a baffle plate to form a template, the pouring of epoxy concrete is restricted, thereby solving the problems mentioned in the background art, namely, the low underwater temperature and long operation time in winter, which also increases the safety risks for underwater workers.

[0009] To achieve the above objectives, the underwater repair method for leakage points in a concrete-faced dam includes the following steps: S1. Remove the damaged panel; S2. Locate the leakage point and install a baffle plate on the panel around the leakage point to isolate an injection chamber on the panel. S3. Inject sludge into the leaking area through a conduit. During the injection process, the conduit extends into the injection chamber and uses a baffle to prevent the water flow from impacting the sludge. S4. Use the baffle as the side mold of the template, and install the permeable mesh frame and bolts on the top of the baffle; S5. Pour epoxy concrete into the baffle plate. The epoxy concrete will squeeze the water in the baffle plate through the permeable mesh frame. At the same time, the permeable mesh frame will prevent the epoxy concrete from flowing out, so that the epoxy concrete can be formed. S6. Apply water-stopping treatment to the joints between multiple baffles.

[0010] Based on this, in step S2, the leakage location is located using an underwater high-definition tracking camera. An underwater robot equipped with a high-definition camera captures image information of the damaged area. Ink is sprayed onto the damaged area, and when the ink is absorbed, it indicates that a leakage has occurred at that location.

[0011] Based on this, the steps for installing the baffle in S2 are as follows: S2.1 Weld the four baffles vertically into a frame structure on the ground; S2.2, Angle iron is installed inside the bottom of the baffle; S2.3 Drill corresponding mounting holes on the panel according to the position of the angle iron; S2.4 The baffle is hoisted and placed underwater at the corresponding position by a crane on the water platform. The baffle is fixed to the panel surface by fixing bolts, so that the baffle protrudes from the panel surface.

[0012] Based on this, the height of the baffle is between 20cm and 30cm.

[0013] Based on this, the order of injecting the sludge in S3 is as follows: first inject fine sludge, then inject coarse sludge, and then inject fine sludge again.

[0014] Based on this, the sludge material is a mixture of fly ash and fine sand in a weight ratio of 1:1, and the fine sand has a fineness modulus of 1.3 to 1.8.

[0015] Based on this, the steps for installing the bolts in S4 are as follows: S4.1 During the process of welding the baffle plate on the ground, continue to weld a steel plate on top of the baffle plate. The thickness of the steel plate is 3mm. S4.2 Weld bolts at the corresponding positions on the baffle plate. The bottom end of the bolt passes through the steel plate and enters the injection chamber by 8cm. The top end is used to fix the EPDM rubber cover when installing the water stop.

[0016] Based on this, the permeable mesh frame in S4 includes a steel frame and a steel mesh. The steel mesh is used to intercept epoxy concrete and allow water to pass through. The steps for installing the permeable mesh frame are as follows: S4.3 Embed the steel mesh into the steel frame to form a permeable mesh frame; S4.4 The underwater personnel weld the steel reinforcement frame onto the surface of the steel plate.

[0017] Based on this, the water-stopping treatment step in S6 is as follows: S6.1 After the epoxy concrete is poured, a high-pressure closed-hole plate is installed at the joint between the two sets of baffles. S6.2. Filler is placed at the top of the joint; S6.3. Use EPDM rubber cover sheets to cover the filler. The EPDM rubber cover sheets pass directly through the bolts and are fixed with nuts.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this underwater repair method for seepage points in a concrete-faced dam, the template structure is optimized. A permeable mesh frame and a flow-blocking plate are used together to form the template, restricting the pouring of epoxy concrete. A step-by-step installation method is adopted. On the one hand, during the siltation operation, the flow-blocking plate reduces the impact of water flow on the silt-blocking material, improving the efficiency of the sealing operation. On the other hand, during the epoxy concrete pouring process, only one permeable mesh frame needs to be installed to form the template. Furthermore, bolts are pre-embedded in the flow-blocking plate, allowing the bolts to be pre-embedded in the epoxy concrete, thereby reducing the overall underwater construction time.

[0019] 2. In the underwater repair method for the leakage part of the concrete panel dam, the baffle plate protrudes 20cm from the panel surface. This not only reduces the impact of water flow during the siltation operation, but also makes the top surface of the concrete repair 20cm higher than the top surface of the original panel, thus improving the strength of the concrete repair surface. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 This is a schematic diagram of the template structure of the present invention; Figure 3 This is a schematic diagram of the working state of the catheter of the present invention; Figure 4 This is a schematic diagram of the bolt structure of the present invention.

[0021] The meanings of the labels in the diagram are as follows: 100. Baffle plate; 101. Steel plate; 102. Operating port; 103. Bolt; 104. Rebar frame; 105. Rebar mesh. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] When concrete-faced dams experience panel damage or leakage, repairs are necessary. However, when these dams are used as core water-retaining structures in hydropower stations, the reservoir lacks the capacity for emptying, and the summer peak power generation period prevents lowering the reservoir water level. Therefore, lowering the water level can only be done in winter. Given the lower underwater temperatures in winter, this invention provides an underwater repair method for leaking areas in concrete-faced dams to reduce underwater work time. Figure 1 As shown, the underwater repair method includes the following steps: S1. Remove the damaged panel; S2. Locate the leakage point and install a baffle plate 100 on the panel around the leakage point to isolate an injection chamber on the panel using the baffle plate 100. S3. Injecting plugging material into the leaking area through a conduit. During the injection process, the conduit extends into the injection chamber and uses the baffle plate 100 to prevent the water flow from impacting the plugging material. S4. Use the baffle plate 100 as the side mold of the template, and install the permeable mesh frame and bolts 103 on the top of the baffle plate 100; S5. Pour epoxy concrete into the baffle plate 100. The epoxy concrete squeezes the water in the baffle plate 100 through the permeable mesh frame. At the same time, the permeable mesh frame blocks the epoxy concrete from flowing out, so that the epoxy concrete is formed. S6. Perform water-stopping treatment on the joints between multiple baffles 100.

[0024] The steps described above will be explained in detail below.

[0025] Taking a 100-meter-class concrete panel rockfill dam (such as the panel dam in the Jilebulak Hydropower Station) as an example, the first step is to chisel away and roughen the damaged concrete panel. This is done by divers underwater using handheld pneumatic or hydraulic picks. The depth and extent of the chiseling are determined based on on-site testing results. If only the surface is damaged, the initial chiseling thickness is set at 10-20 cm. After the roughened surface is created, high-pressure water jets are used to wash away any sediment. After the chiseling is completed, leakage detection is performed using underwater high-definition tracking cameras. An underwater robot equipped with a high-definition camera captures images of the damaged area. Ink is then sprayed onto the damaged area. When leakage occurs, a water suction zone is created at the leakage site, drawing in the ink. This allows the location of the leakage to be identified.

[0026] If no leakage is observed at the damaged area, the rebar insertion work is then carried out. Divers use hydraulic drills to create underwater concrete insertion holes with a diameter of φ28. After drilling, the holes are cleaned of sediment using a guide pipe. HRB400 φ25 steel bars are used for the insertion. Divers install the bars underwater using anchoring adhesive, applying it through a guide pipe from the bottom of the hole with a caulking gun. The amount of adhesive applied should be such that it slightly overflows from the hole after the rebar is inserted. The insertion depth of the rebar is 20cm or 30cm into the concrete panel (depending on the amount of concrete removed from the panel), with a spacing of 40cm between rows. Next, a reinforcing steel mesh is installed. The reinforcing steel mesh uses HRB400 φ16 steel bars with a spacing of 200mm between the horizontal and vertical bars. The reinforcing steel mesh is fabricated in sections at the steel processing plant at the dam crest and transported from the dam crest along the dam slope to the water surface via a winch. It is then transported by floating boat to a floating platform, where a crane lifts it to the corresponding underwater position. After the reinforcing steel mesh is hoisted to the corresponding position by a water crane, it is manually tied underwater by divers. The reinforcing steel mesh is connected to the top bend of the reinforcing bar by underwater welding or tying. The thickness of the steel bar protective layer is 5cm.

[0027] If leakage occurs at the damaged area, it indicates that the supporting material at the rear (water-repellent side) of the concrete panel has been washed away by the water flow, leaving the rear of the panel in a void. In this case, a plugging operation should be performed first, followed by the insertion of reinforcing bars and the installation of the reinforcing mesh. The plugging operation method is as follows: refer to Figure 2 First, four baffle plates 100 are vertically welded into a frame structure on the ground. The height of the baffle plates 100 is between 20cm and 30cm, and the length and width are flexibly adjusted according to the actual situation. Angle irons are installed inside the bottom of the baffle plates 100, and corresponding mounting holes are drilled on the panel according to the position of the angle irons. Next, the baffle plates 100 are hoisted and placed in the corresponding positions underwater by a crane on the water platform. At this time, the baffle plates 100 are fixed to the panel surface with fixing bolts, so that the baffle plates 100 protrude from the panel surface.

[0028] Due to the protruding baffle 100, the interior of the frame structure can be isolated from the outside through the baffle 100. In this way, an injection chamber is formed inside the frame structure. Due to the obstruction of the baffle 100, the water in the injection chamber is not affected by the external water flow.

[0029] See again Figure 3 Then, the discharge end of the conduit is extended into the injection chamber, corresponding to the leakage point. At this point, it can be observed that because the discharge end of the conduit is inside the frame-shaped baffle 100, the plugging material discharged from the discharge end of the conduit is also inside the frame-shaped baffle 100. Therefore, the plugging material is only attracted to the leakage point and is not affected by the water flow in the reservoir. In this way, the plugging material is primarily located at the leakage point, thereby accelerating the sealing of the leakage.

[0030] The underwater injection of plugging material employs a "fine-to-coarse-to-fine" injection method. The coarse material consists of medium-coarse sand (or small stones), while the fine material is a mixture of fine sand and fly ash. First, the fine material is injected evenly, and the flow velocity at the crack is observed. If there is a significant decrease, the injection of this type of plugging material continues until it can no longer be drawn in. If the flow velocity at the leakage point does not change significantly, the gradation of the plugging material is adjusted, and injection continues. Continuous observation is maintained during the injection process. Once the flow velocity decreases, a finer-particle plugging material is used, and injection continues until it can no longer be drawn in.

[0031] In this way, underwater plugging material is injected through a conduit. Taking advantage of the fine particles and ease of water flow, the plugging material is carried into the subbase material beneath the panel, effectively blocking leakage channels and filling the loose subbase. This reduces the inlet water velocity at the leakage point and restores the supporting function of the subbase material. The plugging material is a mixture of fly ash and fine sand in a 1:1 weight ratio. The fine sand has a fineness modulus of 1.3–1.8, and the fly ash used is Grade II fly ash.

[0032] After the sealing work is completed, the concrete panel needs to be re-poured. Since it is underwater, underwater epoxy concrete will be used. The epoxy concrete strength grade is C35, the adhesive adhesion is grade 1-2, and the underwater bond strength is greater than 2.5 MPa. Refer to the mix proportions in the table below, and adjust according to the site temperature and sand particle size. On-site mix proportion tests should be conducted according to the material manufacturer's requirements.

[0033] Epoxy Concrete Reference Mix Proportion Table:

[0034] In order to restrict the epoxy concrete during the pouring process, it is currently necessary to install formwork. At the same time, the compressive strength of the epoxy concrete can reach 50-100MPa. If the bolts 103 are installed after the epoxy concrete has been formed, drilling operations are required in the epoxy concrete, which is quite difficult. As a result, the installation of formwork and drilling operations lead to a long overall underwater construction time.

[0035] Therefore, in this invention, the baffle plate 100 is used as the side mold of the template, and the bolts 103 are pre-embedded in the baffle plate 100, so that only an additional permeable mesh frame (i.e., top mold) needs to be installed for the pouring operation. Specifically, as follows... Figure 2 As shown, during the welding of the baffle plate 100 on the ground, a steel plate 101, approximately 3mm thick, is welded to the top of the baffle plate 100. The steel plate 101 has a U-shaped structure, and its internal operating port 102 still allows the conduit to be inserted. Next, bolts 103 are welded to the corresponding positions on the baffle plate 100. The bottom end of the bolt 103 passes through the steel plate 101 into the injection chamber about 8cm, and the top end is used to fix the EPDM rubber cover when installing the water stop. To ensure that the bolt 103 and the hole on the flat steel strip of the water stop rubber cover are aligned, the flat steel strip and the steel plate 101 are overlapped and fixed. A drilling rig is used to drill holes in the steel plate 101 through the holes in the flat steel strip to ensure alignment. After this construction is completed, the baffle plate 100 is installed in the corresponding underwater position for sealing operations.

[0036] After the sealing work is completed, the permeable mesh structure is constructed. This structure includes a steel frame 104 and a steel mesh 105. The steel frame 104 uses HRB400 φ16 steel bars (200mm spacing) as its skeleton. The steel mesh 105 is embedded within the steel frame 104, forming the permeable mesh structure. The steel mesh 105 has sufficient strength, a wire diameter of φ1.2mm, and a mesh size of 2-3mm, effectively blocking the newly poured epoxy concrete. After the permeable mesh structure is welded on the ground, it is hoisted to the top of the steel plate 101. Divers then weld the steel frame 104 to the surface of the steel plate 101. At this point, epoxy concrete is poured into the injection chamber. The epoxy concrete is mixed on the ground and then placed in a bucket, which is then lifted to the divers' location. The divers pour the epoxy concrete from the bucket into the injection chamber, completing the pouring of the panel.

[0037] It should be noted that divers can pour epoxy concrete from the ash bucket into the pouring chamber through the gap at the 105th position of the steel mesh, or an additional pouring port can be set up; this invention does not limit the scope of the invention.

[0038] like Figure 4As shown, after the epoxy concrete is poured, a high-pressure closed-hole plate is installed at the joint between the two sets of baffles 100. Then, filler is installed on the top of the joint and covered with an EPDM rubber cover. The EPDM rubber cover can pass directly through the bolt 103. At this time, a nut is installed on the bolt 103 to complete the surface water-stopping construction.

[0039] This invention optimizes the template structure, using a permeable mesh frame and a baffle plate 100 to jointly form a template to restrict the pouring of epoxy concrete, and employs a step-by-step installation method. On the one hand, during the siltation operation, the baffle plate 100 reduces the impact of water flow on the siltation material, improving the efficiency of the siltation operation; on the other hand, during the epoxy concrete pouring process, only one permeable mesh frame needs to be installed to form the template. Furthermore, bolts 103 are pre-embedded in the baffle plate 100, allowing the bolts 103 to be pre-embedded into the epoxy concrete, thereby reducing the overall underwater construction time.

[0040] Furthermore, the baffle plate 100 protrudes 20cm from the panel surface, which not only reduces the impact of water flow during the sludge removal process, but also makes the top surface of the concrete repair 20cm higher than the original panel surface, thus improving the strength of the concrete repair surface.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for underwater repair of leakage points in concrete-faced dams, characterized in that: Includes the following steps: S1. Remove the damaged panel; S2. Locate the leakage point and install a baffle (100) on the panel around the leakage point to isolate an injection chamber on the panel. S3. Inject sludge into the leaking area through the conduit. During the injection process, the conduit extends into the injection chamber and uses the baffle (100) to prevent the water flow from impacting the sludge. S4. Use the baffle plate (100) as the side mold of the template, and install the permeable mesh frame and bolts (103) on the top of the baffle plate (100). S5. Epoxy concrete is poured into the baffle (100). The epoxy concrete squeezes the water in the baffle (100) through the permeable mesh frame, while the permeable mesh frame blocks the epoxy concrete from flowing out, so that the epoxy concrete is formed. S6. Waterproofing treatment is applied to the joints between multiple baffles (100).

2. The underwater repair method for leakage points of concrete-faced dams according to claim 1, characterized in that: In S2, the leakage point is located using an underwater high-definition tracking camera. An underwater robot equipped with a high-definition camera captures images of the damaged area. Ink is sprayed onto the damaged area, and when the ink is absorbed, it indicates that a leakage has occurred at that location.

3. The underwater repair method for leakage points of concrete-faced dams according to claim 1, characterized in that: The steps for installing the baffle (100) in S2 are as follows: S2.1 Weld the four baffles (100) vertically into a frame structure on the ground; S2.2 Angle iron is installed inside the bottom of the baffle (100); S2.3 Drill corresponding mounting holes on the panel according to the position of the angle iron; S2.4 The baffle (100) is hoisted and placed underwater at the corresponding position by a crane on the water platform. The baffle (100) is fixed to the panel surface by fixing bolts, so that the baffle (100) protrudes from the panel surface.

4. The underwater repair method for leakage points of concrete-faced dams according to claim 3, characterized in that: The height of the baffle (100) is between 20cm and 30cm.

5. The underwater repair method for leakage points of concrete-faced dams according to claim 1, characterized in that: The order of injecting the sludge in S3 is as follows: first inject fine sludge, then inject coarse sludge, and then inject fine sludge again.

6. The underwater repair method for leakage points of concrete-faced dams according to claim 5, characterized in that: The sludge material is a mixture of fly ash and fine sand in a weight ratio of 1:1, with the fine sand having a fineness modulus of 1.3 to 1.

8.

7. The underwater repair method for leakage points of concrete-faced dams according to claim 1, characterized in that: The steps for installing bolt (103) in S4 are as follows: S4.1 During the process of welding the baffle plate (100) on the ground, continue to weld the steel plate (101) on the top of the baffle plate (100), the thickness of the steel plate (101) is 3mm; S4.2 Weld bolts (103) at the corresponding positions on the baffle (100). The bottom end of the bolt (103) passes through the steel plate and enters the injection chamber by 8cm. The top end is used to fix the EPDM rubber cover when installing the water stop.

8. The underwater repair method for leakage points of concrete-faced dams according to claim 7, characterized in that: The permeable mesh frame in S4 includes a steel frame (104) and a steel mesh (105). The steel mesh (105) is used to intercept epoxy concrete and allow water to pass through. The steps for installing the permeable mesh frame are as follows: S4.3 Embed the steel mesh (105) into the steel frame (104) to form a permeable mesh frame; S4.4 Underwater personnel weld the steel reinforcement frame (104) onto the surface of the steel plate (101).

9. The underwater repair method for leakage points of concrete-faced dams according to claim 7, characterized in that: The steps for water-stopping treatment in S6 are as follows: S6.1 After the epoxy concrete is poured, a high-pressure closed-hole plate is installed at the joint between the two sets of baffles (100). S6.

2. Filler is placed at the top of the joint; S6.

3. Use EPDM rubber cover to cover the filler. The EPDM rubber cover passes directly through the bolt (103) and is fixed by the nut.

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