Underwater repair method for concrete of trash rack gate slot of hydropower station

Abstract

The method for underwater repair of concrete of trash rack gate slot of hydropower station includes the steps of: installing underwater working platform, positioning divers and tools and materials, treating slot hole interface, sealing slot hole with template, and pumping underwater non-diffusion fast-setting concrete. The method is used for underwater operation without structural modification. By utilizing the structure of trash rack, an underwater working platform is set on the steel gate of trash rack. The underwater working platform provides a storage platform for tools and materials, reduces the time of tool and material transportation, and provides a work place for divers to reduce the difficulty of operation. At the same time, the support rod is used to form an underwater template support system, which ensures that the template can provide support for complex environment in water, reduces the time of template installation, and improves the operation efficiency.

Description

Technical Field

[0001] The invention relates to a construction technology problem of a hydroelectric power station, and in particular to an underwater repair method for a trash rack gate slot concrete of a hydroelectric power station. Background Art

[0002] Since the invention of hydroelectric power stations, the second-phase concrete of the trash rack gate slot has been prone to difficulty in repairing during operation in both domestic and foreign power stations due to the combined effects of water scouring, wheel pressure wear and its own quality. Therefore, how to achieve the repair of the second-phase concrete of the trash rack gate slot during operation has been an issue that many technical personnel have explored.

[0003] Wu Yingli and others from the Nanjing Hydraulic Research Institute of the Ministry of Water Resources, the Ministry of Transport and the National Energy Administration invented "An underwater repair system for the void area of ​​a concrete panel rockfill dam" (CN 109778789 A). By forming a partially closed waterless space inside the working chamber, combined with a drilling device and a grouting device, the system can complete the underwater economical and efficient repair of the void area of ​​a concrete panel rockfill dam; Fan Ming and others from Changsha University of Science and Technology invented "A combined underwater repair structure for leakage of dam concrete anti-seepage panels" (CN 210946696 U). The system can perform economical, effective, rapid and safe anti-seepage repair treatment on three common leakage sites of dam concrete anti-seepage panels: structural joint leakage sites, through-crack leakage sites and deformation and fracture leakage sites; Xie Erlei from Nanjing Yangzi Concrete Products Co., Ltd. invented "An underwater concrete crack repair structure" (CN211949732 U), by arranging a repair material bucket on the top of the I-shaped movable plate, the repair material in the repair material bucket can flow into the syringe through the inside of the I-shaped movable plate, which provides convenience for underwater crack repair.

[0004] The above technical solutions can all be used for underwater concrete repair. However, one of the methods requires the establishment of a waterless space for concrete repair. This method has complicated steps and a long construction period, which affects the normal operation of the hydropower station dam. The other two methods require the modification of the hydropower station dam structure, which is difficult to apply to the built hydropower station dam. Therefore, the commonly used underwater repair method is to use divers to enter the water to perform concrete repair operations using templates, and this method has the following technical problems:

[0005] 1) There is no reaction force support structure on the water channel side during the second phase of concrete repair. The traditional reinforcement method of the template adopts anchoring, which requires underwater welding and underwater mechanical drilling anchoring; 2) There is no vertical support structure during diving operations, and it is difficult for divers to ascend, descend, and adjust their postures, which is inefficient, especially when carrying heavy objects or installing templates; 3) There is no platform for temporary transfer and storage of tools and materials. Divers need to wait for materials in the water, which increases the diving operation time and difficulty. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an underwater repair method for the concrete of the trash rack gate slot of a hydropower station. The method is used for underwater operations and does not require structural modification. By utilizing the structure of the trash rack, an underwater working platform is set on the steel gate of the trash rack. The underwater working platform provides a storage platform for tools and materials, thereby reducing the transportation time of tools and materials, and also provides a working place for divers to reduce the difficulty of operations. At the same time, support rods are used to form an underwater formwork support system, which ensures that the formwork can provide support for complex environments in the water, reduces the template installation time, and improves work efficiency.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a method for underwater repairing concrete of a trash rack gate slot of a hydropower station, comprising the following steps:

[0008] Installation of underwater working platform: Choose to install the underwater working platform on water or in water according to the location of the slot hole to be repaired in the dam body; when the slot hole is located in the upper part of the dam body, install it on water, lift the trash rack above the water surface or the top of the gate pier, and install the underwater working platform on the steel gate of the trash rack; when the slot hole is located in the lower part of the dam body, install it in water, and transport the components of the underwater working platform vertically to the installation position in the water according to the installation sequence for installation;

[0009] Divers and tools and materials are in place: After the underwater working platform is installed on the water, the trash rack steel gate is lowered, and the underwater working platform, tools and materials and diving workers are lowered to the working position along with the trash rack steel gate; After the underwater working platform is installed in the water, the divers dive to the underwater working platform and hoist the tools and materials onto the underwater working platform;

[0010] Slot and hole interface treatment: Diving workers carry out slot and hole interface treatment on the underwater working platform. The slot and hole interface treatment includes two steps, loose concrete removal and high-pressure water gun flushing, or one of the two steps;

[0011] Template to close the slot: Diving workers set up the template on the underwater working platform and install the template on the slot to close the slot. The template is fixed by a support rod. One end of the support rod is connected to the template, and the other end is placed on top or fixed on the underwater working platform or steel gate.

[0012] Pumping underwater non-diffusion fast-setting concrete: There are pouring holes reserved on the formwork. The diving workers insert the concrete pumping hose into the slot through the pouring holes on the formwork, and pump concrete into the slot through the concrete pumping hose until the slot is poured.

[0013] As a further improvement of the present invention, the steel gate of the trash rack is of an inclined structure. When the underwater working platform is installed on the positive slope or the back slope of the steel gate, it is installed using an adjustable support rod, one end of which is connected to the bottom of the underwater working platform, and the other end is connected to the steel gate obliquely downward; when the underwater working platform is installed on the back slope of the steel gate, an adjustable support rod is used, one end of which is connected to the steel gate, and the other end is respectively suspended on the four corner points of the underwater working platform.

[0014] As a further improvement of the present invention, when processing the groove-hole interface, the diving operator first checks the groove-hole interface and manually knocks out or pries off the loose concrete blocks; the diving operator holds a high-pressure water gun with the nozzle perpendicular to the spray cleaning surface, and reciprocates the groove-hole interface with high-pressure water at a pressure of ≥10Mmpa. In order to reduce underwater resistance, the nozzle of the gun is ≤5cm away from the groove-hole interface, and the groove-hole interface is flushed until the concrete at the groove-hole interface shows a white color.

[0015] As a further improvement of the present invention, when the template is used to close the slot, the template is composed of multiple aluminum alloy templates arranged vertically and horizontally and connected by snap-fit ​​connections. The rigidity and strength of the template meet the requirements of the maximum lateral pressure of the newly poured concrete on the template. Sealant is arranged between the template and the outer side of the slot. The template is supported and fixed by a movable support rod. A horizontal slot is provided on the back of the template, and a spherical hinge is slidably provided on the horizontal slot. The movable support rod is a retractable structure, and a universal hinge is provided at the connecting end. The universal hinge of the movable support rod is connected to the spherical hinge on the template, so that the movable support rod can move horizontally and at a large angle.

[0016] As a further improvement of the present invention, the calculation formula of the reaction force provided by the active support rod to the template is F=0.12γ C t0β1β2V 1 / 2 +PS1S2 / S3, where F is the maximum lateral pressure of newly poured concrete on the formwork (KN / m 2 ); γ C : Gravity density of underwater concrete (take 14KN / m 2 ); t0: initial setting time of newly poured concrete (h), measured in water; V: pouring speed of concrete (m / h); β1: admixture correction factor, when adding early setting admixture, take 0.8; β2: concrete slump correction factor, when the slump is 150mm-180mm, take 1.20; P: final grouting pressure, take 0.05MPa; S1: grouting pipe cross-sectional area (m 2 ); S2: Area of ​​side template of movable support rod (m 2 ); S3: total template area (m 2 ).

[0017] As a further improvement of the present invention, a pouring hole is reserved in the upper part of the template. When pumping underwater non-diffusion fast-setting concrete, the diving operator inserts the concrete pumping hose into the bottom of the slot hole as much as possible, and a concrete pump is arranged on the top of the trash rack dam. The concrete pumping hose is connected to the concrete pump at the top of the trash rack dam. The diving operator communicates with the personnel on the top of the dam through a diving intercom underwater, starts the concrete pump to pump underwater non-diffusion fast-setting concrete, and while pumping concrete, on the premise of ensuring that the poured concrete wraps the outlet of the concrete pumping hose, shrinks the pipe in the slot hole in time. When the diving operator observes that slurry overflows from the uppermost template of the slot hole, he notifies to stop pouring, closes the pipeline at the mold entry, and removes the pumping pipe.

[0018] As a further improvement of the present invention, the mix ratio of underwater non-diffusion fast-setting concrete is cement: sand: stone: water = 1: 2.6: 3.9: 0.35, wherein the composition of water is water reducer: accelerator: drinking water: pumping agent = 1: 1: 45: 2.

[0019] As a further improvement of the present invention, the step of preparing a dam crest working platform is also included: according to the relationship between the top of the trash rack gate slot and the dam crest road or other existing platforms on the dam crest, an existing dam crest platform on the dam crest road surface or in close proximity is selected as the dam crest working platform, and edge protection is set around the platform. The platform area is greater than 6 square meters, which meets the requirements for placing small fine stone concrete pumps, electric welding machines, miscellaneous materials, and machinery storage, and meets the requirements for pre-diving work preparation of diving operators.

[0020] As a further improvement of the present invention, it also includes the step of underwater diving detection: after the diving workers have made preparations for diving operations on the dam top according to safety requirements, they use a steel tape measure to measure and calibrate the position markings of the gate slot and hole, and use underwater video and photography equipment to collect digital video of the current status of the slot and hole, and feed back the collected data to technical personnel to improve the slot and hole repair plan.

[0021] As a further improvement of the present invention, it also includes the steps of demolding and quality inspection: the final setting time is determined according to the underwater concrete curing test. After the underwater concrete pouring has finally set, the diving workers dive down to loosen the support rods, remove the formwork, and check the concrete pouring surface. When the concrete surface is flat, without honeycombs and obvious large bubbles, the quality is qualified.

[0022] As a further improvement of the present invention, the step of dismantling the underwater working platform is also included: after the construction is completed, for the underwater working platform located on the upper part of the dam body, the steel gate is first lifted to the vicinity of the pier top, and then the underwater working platform is dismantled; for the underwater working platform located at the lower part of the dam body, it is dismantled directly in the water, and the dismantling follows the principle of "dismantling those installed first and those installed later first".

[0023] The beneficial effects of the present invention are:

[0024] This method is used for underwater operations, and there is no need to structurally modify the trash rack gate slot, and only an underwater work platform needs to be added. When installing the underwater work platform on the water, this method makes full use of the lifting structure of the trash rack to implement it. After the steel gate of the trash rack is raised, the underwater work platform is installed on the water surface, which can greatly improve safety and ease of operation compared to underwater installation. After the underwater work platform is installed on the water surface, the underwater work platform, tools and materials, and diving workers are lowered to the working position along with the trash rack steel gate, thereby reducing the transportation time of tools and materials and the diving time of diving workers. When installing the underwater work platform in the water, this method transports the components vertically in sequence so that the components can be installed in an orderly manner, thereby realizing the rapid installation of the underwater work platform. During operation, the underwater work platform can provide a docking work place for diving workers and a stable storage platform for tools and materials. In addition, an underwater formwork support system can be formed through support rods, and the formwork can be fixed on the underwater working platform or steel gate by pressing it against the reaction force of the support rods. Compared with the previous underwater formwork welding fixation and underwater mechanical drilling and anchoring methods, it is more efficient and easier to operate, enabling diving workers to achieve fast and safe operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the construction site;

[0026] Figure 2 This is a schematic diagram of underwater operations;

[0027] Figure 3 This is a schematic diagram of the underwater working platform on the positive slope side;

[0028] Figure 4 This is a schematic diagram of the underwater working platform on the anticline side;

[0029] Figure 5 It is a schematic diagram of the template structure;

[0030] Marking description: dam top working platform 1, diving operator 2, dam body 3, steel gate 4, underwater working platform 5, adjustable support rod 51, template 6, horizontal slot 61, spherical hinge 62, pouring hole 63, movable support rod 7, universal hinge 71. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] like Figure 1-5 As shown, a method for underwater repairing concrete of a trash rack gate slot of a hydropower station comprises the following steps:

[0033] (1) Preparation of the dam crest working platform: Based on the relationship between the top of the trash rack gate slot and the dam crest road or other existing platforms on the dam crest, select an existing dam crest platform on the dam crest road surface or in close proximity as the dam crest working platform 1. Edge protection is set up around the dam crest working platform 1. The platform area is greater than 6 m2, which can accommodate small fine stone concrete pumps, electric welding machines, miscellaneous materials, and equipment storage requirements, and meet the pre-diving preparation requirements of diving operators 2.

[0034] (2) Underwater non-diffusion fast-setting concrete is prepared according to the mix ratio: Underwater non-diffusion fast-setting concrete is prepared in a laboratory with conditions. The mix ratio of underwater non-diffusion fast-setting concrete meets the comprehensive requirements of pumping requirements, C30 strength requirements and rapid setting (3d compressive strength ≥ 25MPa); local ground materials and major brand main materials, high-efficiency water reducer (of which the stone is 05 crushed stone) are used. The final mix ratio of underwater non-diffusion fast-setting concrete is cement: sand: stone: water = 1: 2.6: 3.9: 0.35, of which the composition of water is water reducer: accelerator: drinking water: pumping agent = 1: 1: 45: 2.

[0035] (3) Underwater diving detection: After the diving operator 2 has made preparations for the diving operation on the dam top according to safety requirements, he uses a steel tape measure to measure and mark the position of the gate slot hole, and uses underwater video and photography equipment to collect digital video of the current status of the slot hole. The collected data is fed back to the technical staff to improve the slot hole repair plan.

[0036] (4) Installation of the underwater working platform: Select the installation on water or in water according to the location of the slot hole that needs to be repaired in the dam body 3. When the slot hole is located in the upper part of the dam body 3, carry out the installation on water, lift the trash rack steel gate 4 to the top of the water surface or the top of the gate pier, and install the underwater working platform 5 on the steel gate 4 of the trash rack; when the slot hole is located in the lower part of the dam body 3, carry out the installation in water, first conduct a trial assembly on the water surface, accumulate experience and improve the structure in time, and then transport the components of the underwater working platform 5 vertically to the underwater installation position in the installation order for installation (first come first served). The steel gate 4 of the trash rack is an inclined structure. When installing, the underwater working platform 5 is installed on the positive slope or the reverse slope of the steel gate 4 according to the working position. Figure 3 As shown, when the underwater working platform 5 is installed on the positive slope of the steel gate 4, an adjustable support rod 51 is used for installation. One end of the adjustable support rod 51 is connected to the bottom of the underwater working platform 5, and the other end is welded obliquely downward to the horizontal bar of the steel gate 4; Figure 4 As shown, when the underwater working platform 5 is installed on the back slope of the steel gate 4, an adjustable support rod 51 is used, one end of the adjustable support rod 51 is welded to the steel gate 4, and the other end is respectively suspended at the four corner points of the underwater working platform 5, and the force point is at the top of the adjustable support rod 51. The diving operator 2 uses the working method of standing on the underwater working platform 5 when working on the template 6 and pouring underwater concrete.

[0037] (5) Divers and tools and materials are in place: After the underwater work platform 5 is installed on the water, the template 6, support rods, high-pressure washing guns, wrenches and other tools and materials are placed on the underwater work platform 5, and the diving operator 2 also enters the underwater work platform 5, and then lowers the trash rack steel gate 4. The underwater work platform 5, tools and materials and the diving operator 2 are lowered to the working position along with the trash rack steel gate 4. In addition, the tools and materials can also be fixed on the inclined surface of the grille by connecting the tools with fasteners. After the underwater work platform 5 is installed in the water, the diver dives into the underwater work platform 5 and hoists the tools and materials onto the underwater work platform 5.

[0038] (6) Treatment of the slot interface: The diving operator 2 performs slot interface treatment on the underwater working platform 5. When performing slot interface treatment, the diving operator 2 first checks the slot interface and manually knocks out or pries out the loose concrete blocks; the diving operator 2 holds a high-pressure water gun with the nozzle perpendicular to the spray cleaning surface, and repeatedly flushes the slot interface with high-pressure water at a pressure of ≥10Mmpa. In order to reduce underwater resistance, the nozzle is ≤5cm away from the slot interface, and flushes until the concrete at the slot interface turns white.

[0039] (7) Template to close the slot: The diving operator 2 sets the template 6 on the underwater working platform 5, installs the template 6 on the slot to close the slot, and sets a sealant between the template 6 and the outside of the slot. The template 6 is fixed by a support rod, one end of which is connected to the template 6, and the other end is placed on top or fixed on the underwater working platform 5 or the steel gate 4. Figure 5 As shown, in this embodiment, the support rod is placed on top of the steel gate 4. The template 6 is composed of a plurality of aluminum alloy templates 6 arranged vertically and horizontally and connected by snap-fit ​​connections. The rigidity and strength of the template 6 meet the requirements of the maximum lateral pressure of the newly poured concrete on the template 6. The template 6 is supported and fixed by a movable support rod 7. A horizontal slot 61 is provided on the back of the template 6. A spherical hinge 62 is slidably provided on the horizontal slot 61. The movable support rod 7 is a retractable structure. A universal hinge 71 is provided at the connecting end. The universal hinge 71 of the movable support rod 7 is connected to the spherical hinge 62 on the template 6, so that the movable support rod 7 can move horizontally and at a large angle. The reaction force calculation formula provided by the movable support rod 7 to the template 6 is F=0.12γ C t0β1β2V 1 / 2 +PS1S2 / S3, where F is the maximum lateral pressure of the newly poured concrete on the formwork 6 (KN / m 2 ); γ C : Gravity density of underwater concrete (take 14KN / m 2); t0: initial setting time of newly poured concrete (h), measured in water; V: pouring speed of concrete (m / h); β1: admixture correction factor, when adding early setting admixture, take 0.8; β2: concrete slump correction factor, when the slump is 150mm-180mm, take 1.20; P: final grouting pressure, take 0.05MPa; S1: grouting pipe cross-sectional area (m 2 ); S2: Area of ​​side template 6 of movable support rod 7 (m 2 ); S3: total template 6 area (m 2 ). The reaction force is transmitted to the system: pressure on the template 6 side --- spherical hinge 62 --- movable support rod 7 --- trash rack steel gate 4 --- the other side of the gate pier.

[0040] (8) Pumping underwater non-diffusion fast-setting concrete: A pouring hole 63 is reserved on the upper part of the template 6. The diving operator 2 inserts the concrete pumping hose into the slot through the pouring hole 63 on the template 6 and inserts it as far as possible into the bottom of the slot. The dam top working platform 1 is provided with a concrete pump. The concrete pumping hose is connected to the concrete pump of the dam top working platform 1. The diving operator 2 communicates with the personnel on the dam top through the diving intercom underwater, starts the concrete pump to pump underwater non-diffusion fast-setting concrete. While pumping concrete, on the premise of ensuring that the poured concrete wraps the outlet of the concrete pumping hose, the pipe in the slot is retracted in time. When the diving operator 2 observes that slurry overflows from the uppermost template 6 of the slot, he notifies to stop pouring, closes the pipe at the mold entry, and removes the pumping pipe.

[0041] (9) Formwork removal and quality inspection: The final setting time is determined according to the underwater concrete curing test. After the underwater concrete pouring has finally set, the diving operator 2 dives down to loosen the movable support rod 7, remove the formwork 6, and inspect the concrete pouring surface. When the concrete surface is flat, without honeycombs and obvious large bubbles, the quality is qualified.

[0042] (10) Removing the underwater working platform: Repeat steps (5) to (9). After all the slots are repaired, for the underwater working platform 5 located on the upper part of the dam body 3, first lift the steel gate 4 to the vicinity of the pier top, and then use tools such as gas cutting and wrenches to remove the underwater working platform 5 and the adjustable support rod 51; for the underwater working platform 5 located on the lower part of the dam body 3, remove it directly in the water, and follow the principle of "remove the first installed one last, and remove the last installed one first".

[0043] The above method has the following effects:

[0044] (1) Form a set of standardized, safe and effective process flow. The invention has been proved to be standardized, safe and effective through the underwater repair practice of the trash rack gate slot of Hunan Xiushan Hydropower Station and the inlet working gate slot of Hunan Anjiang Hydropower Station during the operation period.

[0045] (2) Realize repair without downtime. During underwater operation, the unit where the gate slot is located and the adjacent units are stopped from generating electricity, which satisfies the underwater operation, and other hydropower station units can generate electricity and operate normally.

[0046] (3) Short construction period and early power generation after repair. With the technology of the present invention, the underwater repair period can be controlled within 2 days; the present invention adopts a low water-cement ratio, a high-efficiency water reducer and a mix ratio of an accelerated setting early strength agent, so that the concrete reaches the strength requirement of passing through water within 3 days, and the unit can be restored to power generation 72 hours after the concrete is poured.

[0047] (4) The steel gate device is used to improve the safety of underwater operations. By installing an underwater operation platform 5 and a movable support rod 7 on the steel gate 4, the diving workers 2 have a docking work place. With the structure of the movable support rod 7 and the combined formwork 6, fast and safe operations are achieved.

[0048] (5) The underwater repair template support system has been innovated. The vertical and horizontal clip-on aluminum alloy template 6 is used to achieve lightweight installation while meeting the rigidity of the template 6. Together with the movable support rod 7, a suitable underwater template 6 support system is formed.

[0049] (6) A fast-setting, early-strength concrete mix suitable for underwater concrete repair in power stations during operation was developed.

[0050] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention in any form. Any person with ordinary knowledge in the technical field may make equivalent embodiments that are partially changed or modified by the technical contents disclosed in the present invention without departing from the scope of the technical features of the present invention, and the equivalent embodiments that do not depart from the technical features of the present invention are still within the scope of the technical features of the present invention.

Claims

1. Underwater repair method for concrete of trash rack gate slot of hydropower station, Features The following steps are involved: Installation of underwater working platform: Choose to install the underwater working platform on water or in water according to the location of the slot hole to be repaired in the dam body; when the slot hole is located in the upper part of the dam body, install it on water, lift the trash rack above the water surface or the top of the gate pier, and install the underwater working platform on the steel gate of the trash rack; when the slot hole is located in the lower part of the dam body, install it in water, and transport the components of the underwater working platform vertically to the installation position in the water according to the installation sequence for installation; Divers and tools and materials are in place: After the underwater working platform is installed on the water, the trash rack steel gate is lowered, and the underwater working platform, tools and materials and diving workers are lowered to the working position along with the trash rack steel gate; After the underwater working platform is installed in the water, the divers dive to the underwater working platform and hoist the tools and materials onto the underwater working platform; Slot and hole interface treatment: Diving workers carry out slot and hole interface treatment on the underwater working platform. The slot and hole interface treatment includes two steps, loose concrete removal and high-pressure water gun flushing, or one of the two steps; The template closes the slot hole: the diving workers set up the template on the underwater working platform and install the template on the slot hole to close the slot hole. The template is fixed by a support rod. One end of the support rod is connected to the template, and the other end is placed on the top or fixed on the underwater working platform or the steel gate. The template is composed of multiple aluminum alloy templates arranged vertically and horizontally and connected by buckles. The rigidity and strength of the template meet the requirements of the maximum lateral pressure of the newly poured concrete on the template. Sealant is set between the template and the outside of the slot hole. The template is supported and fixed by a movable support rod. A horizontal card slot is set on the back of the template. A spherical hinge is slidably set on the horizontal card slot. The movable support rod is a retractable structure. A universal hinge is set at the connection end. The universal hinge of the movable support rod is connected to the spherical hinge on the template, so that the movable support rod can move horizontally and at a large angle. Pumping underwater non-diffusion fast-setting concrete: There are pouring holes reserved on the formwork. The diving workers insert the concrete pumping hose into the slot through the pouring holes on the formwork, and pump concrete into the slot through the concrete pumping hose until the slot is poured.

2. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: The steel gate of the trash rack is an inclined structure. When the underwater working platform is installed, it is installed on the positive slope or the back slope of the steel gate according to the working position. When the underwater working platform is installed on the positive slope of the steel gate, it is installed with an adjustable support rod, one end of which is connected to the bottom of the underwater working platform, and the other end is connected to the steel gate obliquely downward; when the underwater working platform is installed on the back slope of the steel gate, an adjustable support rod is used, one end of which is connected to the steel gate, and the other end is respectively suspended on the four corner points of the underwater working platform.

3. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: When treating the slot-hole interface, the diving workers first check the slot-hole interface and manually knock out or pry off the loose concrete blocks; the diving workers hold a high-pressure water gun with the nozzle perpendicular to the spray cleaning surface, and use high-pressure water with a pressure of ≥10Mpa to reciprocately flush the slot-hole interface. In order to reduce underwater resistance, the nozzle of the gun is ≤5cm away from the slot-hole interface, and flush until the concrete at the slot-hole interface turns white.

4. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: The pouring hole is reserved in the upper part of the formwork. When pumping underwater non-diffusion fast-setting concrete, the diving workers insert the concrete pumping hose into the bottom of the slot as far as possible. A concrete pump is set on the top of the trash rack dam, and the concrete pumping hose is connected to the concrete pump on the top of the trash rack dam. The diving workers communicate with the personnel on the top of the dam through the diving intercom underwater, start the concrete pump to pump underwater non-diffusion fast-setting concrete, and while pumping concrete, timely shrink the pipe in the slot while ensuring that the poured concrete wraps the outlet of the concrete pumping hose. When the diving workers observe that slurry overflows from the uppermost formwork of the slot, they notify to stop pouring, close the pipe at the mold entry, and remove the pumping pipe.

5. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: The mix ratio of underwater non-diffusion fast-setting concrete is cement: sand: stone: water = 1:2.6:3.9:0.35, where the composition of water is water reducer: accelerator: drinking water: pumping agent = 1:1:45:

2.

6. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: It also includes the step of preparing the dam top working platform: according to the relationship between the top of the trash rack gate slot and the dam top road or other existing platforms on the dam top, choose an existing dam top platform on the dam top road surface or in close proximity as the dam top working platform, set up edge protection around the platform, and the platform area should be greater than 6 square meters to meet the requirements for placing small fine stone concrete pumps, electric welding machines, miscellaneous materials, and machinery storage, and meet the pre-diving preparation requirements of diving operators.

7. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: It also includes the steps of underwater diving detection: after the diving workers have made preparations for diving operations on the dam top according to safety requirements, they use a steel tape measure to measure and mark the position of the gate slot and hole, and use underwater video equipment to digitally capture the current status of the slot and hole, and feed back the collected data to technical personnel to improve the slot and hole repair plan.

8. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: It also includes the steps of demolding and quality inspection: the final setting time is determined according to the underwater concrete curing test. After the underwater concrete pouring has finally set, the diving workers dive down, loosen the support rods, remove the formwork, and check the concrete pouring surface. When the concrete surface is flat, without honeycombs and obvious large bubbles, the quality is qualified.

9. The underwater repair method for the trash rack gate groove concrete of a hydropower station according to claim 1, Features: It also includes the step of dismantling the underwater working platform: after the construction is completed, for the underwater working platform located on the upper part of the dam body, first lift the steel gate to near the pier top, and then dismantle the underwater working platform; for the underwater working platform located at the lower part of the dam body, dismantle it directly in the water, and follow the principle of "dismantle those installed first and then those installed later" when dismantling.

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