A method for repairing a reservoir cavity based on a magnetic slurry

Abstract

The application discloses a reservoir cavity repairing method based on magnetic slurry, and belongs to the technical field of reservoir engineering repairing, which takes a thermoplastic polyurethane composite double-layer air bag as a core, a magnetic unit is arranged in the inner bag and connected with an air pump, the outer bag is sealingly connected with a grouting machine provided with a precise control system through a grouting pipe, and the grouting machine contains magnetic slurry containing fibers. The construction is performed through the following steps: the air bag is extended to the far end of the cavity for air inflation and water drainage, the cavity is filled with the slurry, the air bag is recovered, the cavity is sealed with quick-setting magnetic slurry, and the grouting pipe is cut off after solidification. The application realizes the precise fitting of the slurry to the cavity profile through the cooperation of magnetism and slurry, the double-layer air bag can be reused, the compressive strength of the magnetic slurry after solidification is 32-35 MPa, the maintenance time is only 8-12 hours, the use of the reservoir does not need to be interrupted, the method is suitable for cavity repairing under various working conditions, and the filling integrity and construction efficiency are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of water storage tank repair technology, specifically to a method for repairing voids in water storage tanks based on magnetic grout. It is applicable to the repair of voids in various water storage tanks in the fields of construction, municipal engineering, industry and water conservancy, and is especially suitable for repairing water storage tanks with large, irregular voids in flowing water environments. Background Technology

[0002] As a core facility for water resource storage and allocation, reservoirs are widely used in construction, municipal, industrial, and water conservancy projects. Their structural integrity directly affects water resource utilization efficiency and the operational safety of engineering systems. During long-term use, reservoirs are susceptible to various factors such as geological subsidence, long-term water erosion, construction defects, and temperature stress changes. These factors can cause cavities of different sizes and shapes to develop in the reservoir body. If not repaired promptly and effectively, these cavities will gradually expand, leading to serious problems such as leakage, structural cracking, and even collapse, resulting in water waste and engineering safety accidents.

[0003] Currently, the traditional repair method for cavities in water storage tanks is mainly ordinary cement grout injection. Although this method is simple to operate and low in cost, it has many technical drawbacks: First, in a flowing water environment, the cement grout is easily washed away by the water flow, resulting in low grouting efficiency and difficulty in achieving dense filling of cavities; Second, the cement grout has poor fluidity and plasticity, making it unsuitable for large-sized, irregularly shaped cavities, and easily creating dead corners at the edges and gaps of the cavities; Third, the setting speed of the cement grout is poorly controllable. Too long a setting time can lead to grout loss, while too short a setting time can cause blockage of the grouting pipe and incomplete filling; Fourth, the traditional method requires interrupting the use of the water storage tank and carrying out pumping operations, resulting in a long construction period and a significant impact on water resource allocation and normal project operation. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for repairing cavities in water storage tanks based on magnetic grout. This method solves the technical problems of traditional cement grout injection, such as easy loss in flowing water environments, poor adaptability to irregular large-sized cavities, low controllability of solidification speed, and inability to repair cavities while the tank is wet. It achieves dry, precise, and efficient filling of cavities in water storage tanks without interrupting the normal use of the water storage tank.

[0005] To achieve the above-mentioned technical features, the objective of this invention is as follows: The first aspect of this invention provides a method for repairing cavities in a reservoir based on magnetic slurry, comprising the following steps: S1: Insert the uninflated double-layer airbag and the grouting pipe into the far end of the cavity in the water storage tank, and start the air pump connected to the inner bladder of the double-layer airbag to inflate the inner bladder to drain the water in the cavity. S2: Start the grouting machine connected to the grouting pipe, and inject magnetic grout into the gap between the outer bladder of the double-layer airbag and the inner wall of the cavity through the grouting pipe until the magnetic grout completely fills the cavity. Under the pressure of the grout, the double-layer airbag is squeezed out of the cavity, and the double-layer airbag is recovered. S3: Use magnetic grout mixed with accelerator to seal the opening of the cavity; S4: After the magnetic grout inside and at the opening of the cavity has completely solidified, cut off the exposed grouting pipe and seal the cut-off area.

[0006] Preferably, the double-layer airbag is made of thermoplastic polyurethane composite material, and the double-layer airbag includes an independent inner bladder and an outer bladder. The inner wall of the inner bladder is densely distributed with magnetic units, and the outer bladder is integrally sealed with the grouting pipe. The internal channel of the grouting pipe is connected to the inner cavity of the outer bladder, and the outer bladder is provided with grouting holes for grout discharge. The grouting machine is filled with fiber-containing magnetic grout, and the grouting machine is equipped with a precise control system for real-time adjustment of the grouting speed.

[0007] Preferably, the magnetic unit is a neodymium iron boron magnet, and the neodymium iron boron magnet is evenly distributed in an array on the inner wall of the inner bladder; the double-layer airbag is connected to the hook rod through the hanging ring, and in S1, the double-layer airbag is extended into the far end of the cavity through the hook rod.

[0008] Preferably, the fiber is a polyacrylonitrile fiber, the mass content of the polyacrylonitrile fiber in the magnetic slurry is 0.1%~0.5%, and the polyacrylonitrile fiber is not adsorbed by the magnetic unit.

[0009] Preferably, the raw materials of the magnetic slurry are formulated in the following mass ratio: water: silicate cement: sulfoaluminate cement: magnetic powder: water-based epoxy resin: curing agent: flocculant: water-reducing agent = 35~45: 70~90: 15~25: 15~25: 2~4: 2.0~3.0: 0.8~1.2: 0.6~1.0; the magnetic powder is one or a mixture of ferrite magnetic powder and neodymium iron boron magnetic powder.

[0010] Preferably, the accelerator is sodium silicate accelerator, the dosage of sodium silicate accelerator in the magnetic slurry is 3%~8%, and the initial setting time of the magnetic slurry with accelerator is 5~15 min. The grouting speed of the grouting machine in S2 is 5~20L / min. During the grouting process, the uniformity of grout output is maintained to avoid incomplete filling or grout loss caused by fluctuations in grouting speed. The reusability of the double-layer airbag is ≥80%, and the recovered double-layer airbag can be reused after passing the airtightness test; the compressive strength of the magnetic slurry after solidification is 32~35MPa, and the curing time is 8~12h.

[0011] Preferably, for the repair of cavities in small and medium-sized irregular cavities and low-flow-rate water environments, step S1 uses a single hook rod to suspend a double-layer airbag, and the air pump adopts a single-pump inflation mode with an inflation pressure of 0.2~0.4MPa; step S4 further includes a step of using an ultrasonic detection device to detect the density of the cavity filling. If the density is less than 95%, local grouting is performed.

[0012] Preferably, for the repair of cavities in reservoirs with large cavities and high-velocity water environments, the double-layer airbag is a reinforced double-layer airbag, with the outer bladder thickness increased by 20%~50% compared to conventional double-layer airbags, and the magnetic unit density of the inner bladder increased by 30%~60% compared to conventional double-layer airbags; in step S1, the double-layer airbag is hoisted by double hooks, and the air pump adopts a multi-pump parallel inflation mode, inflating in 2~3 stages, with a total inflation pressure of 0.4~0.6MPa; in step S2, the grouting machine is equipped with a double-spiral stirring device, which continuously stirs the magnetic grout during the grouting process to prevent magnetic particles from settling; in step S3, a two-component quick-setting agent injection system is used to simultaneously inject sodium silicate quick-setting agent and magnetic grout into the cavity opening through two pipes in proportion to form a sealing layer; after step S4, ultrasonic real-time monitoring is added, and if local defects are found, secondary supplementary grouting is performed.

[0013] Preferably, for the repair of cavities in reservoirs with ultra-large irregular cavities and high-velocity, highly disturbed water environments, step S1 further includes a step of pre-setting a grouting reinforcement ring around the cavity. The grouting reinforcement ring is formed by magnetic grouting and has a thickness of 10-20 cm. Step S2 involves simultaneous grouting using multiple grouting pipes with a spacing of 0.5-1.0 m between adjacent grouting pipes, and the grouting sequence is from far to near.

[0014] Preferably, for the repair of cavities in shallow, small-sized cavities and low-flow-rate water environments in reservoirs, the double-layer airbag is a micro-airbag with an outer diameter of 60% to 70% of the minimum inner diameter of the cavity; the grouting speed of S2 is 3 to 8 L / min; and S3 uses a troweling method to coat the cavity opening with magnetic grout mixed with an accelerator, with a coating thickness of 5 to 10 cm.

[0015] Beneficial effects of this invention: 1. This invention enables efficient sealing and filling of cavities in water storage tanks. For cavities in water storage tanks, the thermoplastic polyurethane composite material used in the double-layer airbag, with its excellent ductility, high strength, and high airtightness, can tightly adhere to the inner wall of the cavity to form a stable sealed space. Simultaneously, the densely and evenly distributed magnetic units on the inner wall of the airbag can precisely attract magnetic slurry, enabling it to efficiently adsorb and fill the gaps in the cavity, preventing slurry loss and providing reliable technical support for structural reinforcement, seepage prevention, and leak sealing of water storage tanks.

[0016] 2. This invention improves the flexibility and economy of grouting operations for cavities in reservoirs. In the scenario of treating cavities in reservoirs, the design of the grouting pipe tail connecting to the outer bladder and being able to retract and be extruded along with the inner bladder solves the problem of air bladder recovery, significantly reducing construction costs. Furthermore, the position and number of grouting holes on the surface of the outer bladder can be flexibly adjusted according to the actual situation such as the size and shape of the cavity, achieving precise control of the grouting position and ensuring that the grout evenly covers the area to be filled, thus improving the quality and efficiency of the grouting operation.

[0017] 3. This invention ensures the stability and effectiveness of magnetic grout injection. During the filling of voids in water storage tanks, the grouting machine's grouting speed control function allows for flexible adjustment of the grouting rhythm based on the actual conditions of the void. This avoids problems such as grout loss and incomplete void filling caused by excessively fast grouting speed, while also preventing premature solidification of the magnetic grout due to excessively slow grouting speed, which could lead to the inability to recover the double-layer airbags and increased construction costs. This ensures a smooth and orderly grouting process and improves the overall effect of void filling.

[0018] 4. This invention can enhance the structural strength of magnetic slurry after solidification. In applications such as void filling, the polyacrylonitrile fibers added to the magnetic slurry can form a stable fiber network after solidification, significantly improving the compressive and tensile strength of the solidified material and extending its service life. Simultaneously, because the polyacrylonitrile fibers are not attracted by the magnetic units, they can maintain a uniform distribution in the magnetic slurry, avoiding localized strength deficiencies caused by fiber aggregation and ensuring the overall stable and reliable performance of the solidified slurry.

[0019] 5. This invention enables the drying and filling of underground cavities. In the treatment of cavities in areas with high groundwater levels, the air pump can provide sufficient pressure to drive the double-layered airbags to completely drain the accumulated water from the cavity during expansion. This avoids the mixing of accumulated water with the magnetic grout, which would affect the grout's solidification effect, ensuring that the grout solidifies normally in a dry environment. This improves the firmness and seepage prevention performance of the cavity filling, providing a strong guarantee for the safety and stability of the reservoir. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This invention relates to a schematic diagram of airbag placement during the repair of cavities in a small water storage tank.

[0022] Figure 2 This invention relates to a schematic diagram of the device used for grouting during the repair of cavities in a small water storage tank.

[0023] Figure 3 This invention relates to a schematic diagram of airbag placement during the repair of cavities in large water storage tanks.

[0024] Figure 4 This invention relates to a schematic diagram of the device used for grouting during the repair of cavities in a large water storage tank.

[0025] Figure 5 This is a cross-sectional view of the double-layer airbag of the present invention.

[0026] Figure 6 This is a schematic diagram of the distribution of magnetic units inside the inner capsule of the present invention.

[0027] Figure 7 This is a schematic diagram of the magnetic slurry of the present invention.

[0028] In the figure, there are: 1. Double-layer airbag; 2. Cavity; 3. Grouting pipe; 5. Grouting machine; 6. Air pump; 7. Hook rod; 8. Lifting ring; 9. Magnetic unit; 10. Fiber; 11. Magnetic grout; and 12. Grouting hole. Internal capsule 101, external capsule 102. Detailed Implementation

[0029] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0030] Example 1: like Figure 1-7 As shown, a method for repairing cavities in a reservoir based on magnetic slurry includes the following core steps: S1: Insert the uninflated double-layer airbag 1 and the grouting pipe 3 into the far end of the cavity 2 of the water storage tank, and start the air pump 6 connected to the inner bladder of the double-layer airbag 1 to inflate the inner bladder to drain the water accumulated in the cavity 2. S2: Start the grouting machine 5 connected to the grouting pipe 3, and inject magnetic slurry 11 into the gap between the outer bladder of the double-layer airbag 1 and the inner wall of the cavity 2 through the grouting pipe 3 until the magnetic slurry 11 completely fills the cavity 2. Under the pressure of the slurry, the double-layer airbag 1 is squeezed out of the cavity 2, and the airbag is recovered. S3: The opening of the cavity 2 in the water storage tank is sealed by using magnetic slurry 11 mixed with accelerator; S4: After the magnetic grout 11 inside and at the opening of the cavity 2 has completely solidified, cut off the exposed grouting pipe 3 and seal the cut-off part of the pipe.

[0031] Furthermore, the double-layer airbag 1 is made of thermoplastic polyurethane composite material, which has high ductility, high strength and high airtightness, can adapt to cavities 2 of different sizes and is not easily damaged after inflation; the double-layer airbag 1 includes an independent inner bladder 101 and an outer bladder 102. The core function of the inner bladder 101 is to inflate and drain, and the core function of the outer bladder 102 is to guide the magnetic slurry 11 for injection; the inner wall surface of the inner bladder 101 is densely and uniformly arrayed with magnetic units 9, which are neodymium iron boron magnets, which have strong magnetism and can effectively attract the magnetic slurry 11, so that the slurry precisely fits the contour of the cavity 2 and avoids filling dead corners; the outer bladder 102 and the injection pipe 3 form an integrated sealed connection, and the internal channel of the injection pipe 3 is connected to the inner cavity of the outer bladder 102, ensuring that the magnetic slurry 11 smoothly enters the gap between the outer bladder 102 and the inner wall of the cavity 2.

[0032] Furthermore, the double-layer airbag 1 is connected to the hook rod 7 via the lifting ring 8. In S1, the double-layer airbag 1 is slowly extended into the far end of the cavity 2 via the hook rod 7 to avoid the airbag scraping and breaking against the inner wall of the cavity 2. The air pump 6 can be a single pump or multiple pumps in parallel mode. The inflation pressure and inflation speed can be adjusted according to the working conditions of the cavity 2 to ensure that the water in the cavity 2 is completely drained, thereby achieving a dry grouting environment for the cavity 2.

[0033] Furthermore, the grouting machine 5 contains a magnetic grout 11 containing polyacrylonitrile fibers 10. The mass content of the polyacrylonitrile fibers 10 in the magnetic grout 11 is 0.1%~0.5%. These fibers are not adsorbed by the neodymium iron boron magnetic units 9 and can be evenly distributed in the magnetic grout 11. After the grout solidifies, it forms a fiber network, which significantly improves the compressive and tensile strength of the solidified solid. The grouting machine 5 is equipped with a precise control system that can adjust the grouting speed in real time. It can control the grouting speed between 5 and 20 L / min according to the size and shape of the cavity 2 and the water flow conditions, ensuring the uniformity of grout output and avoiding grout loss due to excessively fast grouting speed or premature solidification due to excessively slow grouting speed.

[0034] Furthermore, the raw materials of the magnetic grout 11 are precisely proportioned by mass: water: silicate cement: sulfoaluminate cement: magnetic powder: water-based epoxy resin: curing agent: flocculant: water-reducing agent = 40:80:20:20:3:2.5:1:0.8. The silicate cement and sulfoaluminate cement are compounded to improve the early and later strength of the grout; the magnetic powder is one or a mixture of ferrite magnetic powder and neodymium iron boron magnetic powder, imparting magnetism to the grout and achieving synergistic adsorption with the magnetic unit 9; the water-based epoxy resin and curing agent are compounded to improve the adhesion and impermeability of the grout; the flocculant prevents the grout from dispersing in flowing water, and the water-reducing agent improves the fluidity of the grout, ensuring that the grout smoothly fills the gaps in the voids 2.

[0035] Furthermore, the quick-setting agent used in S3 is sodium silicate quick-setting agent, and its dosage in magnetic grout 11 is 3%~8%, which can control the initial setting time of magnetic grout 11 to 5~15 minutes, realize the rapid sealing of the opening, and prevent the grout in the cavity 2 from being washed away by water flow; after the double-layer airbag 1 is squeezed out of the cavity 2 under the action of grout pressure, it can be reused after cleaning and passing the airtightness test, with a reuse rate of ≥80%, which significantly reduces the cost of construction materials.

[0036] Furthermore, the compressive strength of the magnetic grout 11 after solidification can reach 32~35MPa, which is much higher than that of traditional cement grout, and the curing time is only 8~12h, which greatly shortens the construction cycle; the filling integrity is improved by more than 90% compared with the traditional method, effectively enhancing the structural strength and seepage prevention performance of the repaired water storage tank.

[0037] The present invention also designs four adaptable implementation processes for water storage tank cavities 2 under different working conditions, which are respectively applicable to the repair of small and medium-sized irregular low flow velocity, large high flow velocity, ultra-large irregular high flow velocity with strong disturbance, and shallow surface small size low flow velocity water storage tank cavities 2, achieving full working condition coverage.

[0038] Example 2: Repair of voids in small to medium-sized irregular cavities in water storage tanks with low flow velocity environments This embodiment is applicable to the repair of small and irregular cavities 2 in water storage tanks with a cavity volume ≤ 5m³ and a water flow velocity ≤ 0.3m / s. The specific steps are as follows: S1: Connect the uninflated conventional double-layer airbag 1 to a single hook rod 7 via the lifting ring 8, and slowly insert the double-layer airbag 1 and the grouting pipe 3 together into the far end of the cavity 2 of the water storage tank, ensuring that the airbag does not rub against the inner wall of the cavity 2; start a single air pump 6, and inflate the inner bladder 101 of the double-layer airbag 1 through the inflation pipe 4, with the inflation pressure controlled at 0.3MPa, and continue to inflate until the water in the cavity 2 is completely drained.

[0039] S2: Start the grouting machine 5, set the grouting speed to 10L / min through the precision control system, and inject magnetic grout 11 containing polyacrylonitrile fiber 10 into the gap between the outer bladder 102 of the double-layer airbag 1 and the inner wall of the cavity 2 through the grouting pipe 3. Keep the grout output uniform during the grouting process; until the magnetic grout 11 completely fills the cavity 2, the double-layer airbag 1 is slowly squeezed out of the cavity 2 under the action of grout pressure, and the airbag is recovered. After recovery, the airbag is cleaned and the airtightness is tested.

[0040] S3: Add sodium silicate quick-setting agent at a dosage of 5% to magnetic grout 11, stir evenly, and then seal the opening of void 2 by a combination of troweling and grouting to form a sealing layer with a thickness of 8cm.

[0041] S4: After the magnetic grout 11 inside and at the opening of the cavity 2 has been cured for 10 hours, check the solidification state of the grout. After confirming that it has completely solidified, cut off the exposed grouting pipe 3 and seal the cut-off part of the pipe with sealing mortar.

[0042] S5: The filling density of void 2 was tested using ultrasonic testing equipment. The test results showed that the density reached 98%, with no dead corners or defects, and no need for grouting.

[0043] In this embodiment, the reusability of the double-layer airbag 1 is 85%, the compressive strength of the magnetic slurry 11 after solidification is 34MPa, the entire repair operation does not require interruption of the use of the water storage tank, and the repair cycle of a single cavity 2 is 12 hours.

[0044] Example 3: Repair of cavities in reservoirs with large cavities and high-velocity water environments This embodiment is applicable to the repair of large cavities 2 in water storage tanks with a volume of 5~20m³ and a water flow velocity of 0.3~0.8m / s. The specific steps are as follows: S1: A reinforced double-layer airbag 1 is selected, with the outer bladder 102 having a thickness 30% greater than that of a conventional airbag, and the density of the neodymium iron boron magnetic unit 9 in the inner bladder 101 being 40% higher than that of a conventional airbag; the reinforced double-layer airbag 1 is connected to the double hook rod 7 via the lifting ring 8, and the airbag and grouting pipe 3 are hoisted together to slowly extend into the far end of the cavity 2, avoiding displacement of the airbag due to the impact of high-velocity water flow; the two air pumps 6 are started in parallel system, and inflated in two stages, with the first stage inflation pressure being 0.2MPa and the second stage inflation pressure being 0.5MPa, gradually draining the water accumulated in the cavity 2 to ensure thorough drainage.

[0045] S2: Start the grouting machine 5 equipped with a double spiral stirring device. The stirring device continuously stirs the magnetic grout 11 to prevent magnetic particles from settling. The grouting speed is set to 15L / min through the precise control system. Magnetic grout 11 is injected into the cavity 2 until the grout completely fills the cavity 2. The reinforced double-layer airbag 1 is recovered. Its reuse rate is tested to be 82%.

[0046] S3: A two-component spraying system for sodium silicate quick-setting agent is adopted. Sodium silicate quick-setting agent and magnetic slurry 11 are sprayed simultaneously into the opening of cavity 2 through two pipes at a ratio of 6% to form a sealing layer with a thickness of 15cm. The initial setting time of the sealing layer is 8min.

[0047] S4: After the magnetic grout 11 has been cured for 9 hours, the exposed grouting pipe 3 is cut off and the cut-off part of the pipe is sealed; an ultrasonic real-time monitoring device is added to scan the inside of the cavity 2 and a small filling defect is found. A micro grouting pipe 3 is used for secondary grouting, and the density reaches 97% after grouting.

[0048] In this embodiment, the compressive strength of the magnetic slurry 11 after solidification is 35 MPa. The entire repair operation does not require interruption of the use of the water storage tank, and the repair cycle for a single cavity 2 is 15 hours.

[0049] Example 4: Repair of cavities in a reservoir with ultra-large irregular cavities and high-velocity, highly disturbed water environments. This embodiment is applicable to the repair of ultra-large irregular cavities 2 in reservoirs with a cavity volume > 20m³, a water flow velocity > 0.8m / s, and strong water flow disturbance. The specific steps are as follows: S0: Pre-treatment: Grouting holes are pre-set on the reservoir body around the cavity 2, and the magnetic grout 11 of the present invention is used for grouting to form a grouting reinforcement ring with a thickness of 15cm, to prevent the rock or concrete around the cavity 2 from falling off during the repair process, and at the same time reduce the disturbance of water flow to the inside of the cavity 2.

[0050] S1: An ultra-reinforced double-layer airbag 1 is selected, with the outer bladder 102 having a thickness 50% greater than that of a conventional airbag, and the inner bladder 101 having a neodymium iron boron magnetic unit 9 with a density 60% higher than that of a conventional airbag; three hooks 7 are used for coordinated hoisting, and the airbag and three grouting pipes 3 are extended into the far end of the cavity 2 together. The three grouting pipes 3 are arranged in a triangle with a spacing of 0.8m; three air pumps 6 are started in parallel system, and air is inflated in three stages with inflation pressures of 0.2MPa, 0.4MPa and 0.6MPa respectively, to completely drain the water in the cavity 2.

[0051] S2: Start three grouting machines 5 to grout simultaneously. Each grouting machine 5 is equipped with a double spiral stirring device. The grouting speed of each grouting machine 5 is set to 20L / min through a precise control system. The magnetic grout 11 is injected into the cavity 2 in a grouting sequence from far to near. The grout 11 is injected into the cavity 2 until the cavity 2 is completely filled with grout. The super-reinforced double-layer airbag 1 is then recovered. The reuse rate of the airbag is tested to be 80%.

[0052] S3: A two-component spraying system for sodium silicate quick-setting agent is adopted. The sodium silicate quick-setting agent is mixed with magnetic grout 11 at a dosage of 8% and then sprayed under high pressure to the opening of cavity 2 to form a sealing layer with a thickness of 20cm. The initial setting time of the sealing layer is 5min.

[0053] S4: After the magnetic grout 11 has been cured for 8 hours, the three exposed grouting pipes 3 are cut off and the cut-off parts of the pipes are sealed; the density of the cavity 2 is tested using an ultrasonic + radar dual detection system. The test results show that the density reaches 96% and there are no obvious defects.

[0054] In this embodiment, the compressive strength of the magnetic slurry 11 after solidification is 33 MPa. The entire repair operation does not require interruption of the use of the water storage tank, and the repair cycle for a single cavity 2 is 20 hours.

[0055] Example 5: Repair of shallow, small-sized cavities in a reservoir with low-flow-rate water environment This embodiment is applicable to the repair of small-sized cavities 2 in the shallow surface layer of a water storage tank with a volume ≤1m³, a depth ≤0.5m, and a water flow velocity ≤0.3m / s. The specific steps are as follows: S1: Select a miniature double-layer airbag 1 with an outer diameter that is 65% of the minimum inner diameter of the cavity 2. Connect it to a single miniature hook rod 7 via a lifting ring 8. Insert the miniature airbag and the grouting pipe 3 together into the far end of the cavity 2. Start the small air pump 6 and control the inflation pressure to 0.2MPa to drain the water inside the cavity 2.

[0056] S2: Start the grouting machine 5, set the grouting speed to 5L / min through the precision control system, inject magnetic grout 11 into the cavity 2 until the grout completely fills the cavity 2, and recover the micro double-layer airbag 1. The reuse rate is tested to be 88%.

[0057] S3: Add sodium silicate quick-setting agent at a dosage of 3% to magnetic grout 11, stir evenly, and then apply the grout to the opening of cavity 2 by troweling. The coating thickness is 6cm to form a sealing layer. The initial setting time of the sealing layer is 12min.

[0058] S4: After the magnetic grout 11 has been cured for 12 hours, check the solidification state of the grout, cut off the exposed grouting pipe 3 and seal the cut-off part of the pipe; use the naked eye and a simple rebound hammer to check the filling quality, showing that the filling is dense and the strength meets the standard.

[0059] In this embodiment, the compressive strength of the magnetic slurry 11 after solidification is 32MPa. The entire repair operation does not require interruption of the use of the water storage tank, and the repair cycle for a single cavity 2 is 8 hours.

Claims

1. A method for repairing cavities in a water storage tank based on magnetic slurry, characterized in that, Includes the following steps: S1: Insert the uninflated double-layer airbag (1) and the grouting pipe (3) into the far end of the cavity (2) of the water storage tank, start the air pump (6) connected to the inner bladder (101) of the double-layer airbag (1), inflate the inner bladder (101) to drain the water in the cavity (2); S2: Start the grouting machine (5) connected to the grouting pipe (3), and inject magnetic grout (11) into the gap between the outer bladder (102) of the double-layer airbag (1) and the inner wall of the cavity (2) through the grouting pipe (3) until the magnetic grout (11) completely fills the cavity (2). The double-layer airbag (1) is squeezed out of the cavity (2) under the action of grout pressure, and the double-layer airbag (1) is recovered. S3: The opening of the cavity (2) is sealed by magnetic grout (11) mixed with accelerator; S4: After the magnetic grout (11) inside the cavity (2) and at the opening has completely solidified, cut off the exposed grouting pipe (3) and seal the cut-off part of the pipe.

2. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 1, characterized in that, The double-layer airbag (1) is made of thermoplastic polyurethane composite material. The double-layer airbag (1) includes an inner bladder (101) and an outer bladder (102) that are independent of each other. The inner wall of the inner bladder (101) is densely distributed with magnetic units (9). The outer bladder (102) and the grouting pipe (3) form an integrated sealed connection. The internal channel of the grouting pipe (3) is connected to the inner cavity of the outer bladder (102). The outer bladder (102) is provided with grouting holes (12) for grout discharge. The grouting machine (5) is filled with magnetic grout (11) containing fibers (10). The grouting machine (5) is equipped with a precise control system for real-time adjustment of grouting speed.

3. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 2, characterized in that, The magnetic unit (9) is a neodymium iron boron magnet, and the neodymium iron boron magnet is evenly distributed in an array on the inner wall of the inner bladder (101); the double-layer airbag (1) is connected to the hook rod (7) through the hanging ring (8), and in S1, the double-layer airbag (1) is extended into the far end of the cavity (2) through the hook rod (7).

4. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 2, characterized in that, The fiber (10) is a polyacrylonitrile fiber, and the mass content of the polyacrylonitrile fiber in the magnetic slurry (11) is 0.1%~0.5%, and the polyacrylonitrile fiber is not adsorbed by the magnetic unit (9).

5. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 2, characterized in that, The raw materials of the magnetic slurry (11) are proportioned as follows by mass: water: silicate cement: sulfoaluminate cement: magnetic powder: water-based epoxy resin: curing agent: flocculant: water-reducing agent = 35~45: 70~90: 15~25: 15~25: 2~4: 2.0~3.0: 0.8~1.2: 0.6~1.0; the magnetic powder is one or a mixture of ferrite magnetic powder or neodymium iron boron magnetic powder.

6. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 1, characterized in that, The accelerator is sodium silicate accelerator, and the dosage of sodium silicate accelerator in magnetic slurry (11) is 3%~8%, and the initial setting time of magnetic slurry (11) with accelerator is 5~15min. The grouting speed of the grouting machine (5) in S2 is 5~20L / min. During the grouting process, the uniformity of grout output is maintained to avoid insufficient filling or grout loss caused by fluctuations in grouting speed. The reusability of the double-layer airbag (1) is ≥80%. The double-layer airbag (1) can be reused after passing the airtightness test. The compressive strength of the magnetic slurry (11) after solidification is 32~35MPa and the curing time is 8~12h.

7. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 6, characterized in that, For repairing small and medium-sized irregular cavities (2) and cavities (2) in water storage tanks with low flow velocity water environment, S1 uses a single hook rod (7) to hoist a double-layer airbag (1), and the air pump (6) adopts a single pump inflation mode with an inflation pressure of 0.2~0.4MPa; S4 also includes a step of using an ultrasonic detection device to detect the filling density of the cavity (2). If the density is not above 95%, local grouting is performed.

8. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 6, characterized in that, For the repair of large cavities (2) and cavities (2) in reservoirs with high flow velocity water environments, the double-layer airbag (1) is a reinforced double-layer airbag. The thickness of its outer bladder (102) is 20%~50% greater than that of a conventional double-layer airbag (1), and the density of the magnetic unit (9) of the inner bladder (101) is 30%~60% higher than that of a conventional double-layer airbag (1). The S1 uses double hook rods (7) to lift the double-layer airbag (1) in coordination, and the air pump (6) adopts a multi-pump parallel inflation mode. The air is filled in stages 2-3, with a total air pressure of 0.4-0.6 MPa; the grouting machine (5) in S2 is equipped with a double spiral stirring device, which continuously stirs the magnetic grout (11) during the grouting process to prevent magnetic particles from settling; S3 adopts a two-component quick-setting agent injection system, which sprays sodium silicate quick-setting agent and magnetic grout (11) into the hole in a ratio through two pipes simultaneously to form a sealing layer; after S4, ultrasonic real-time monitoring is added, and if local defects are found, secondary supplementary grouting is carried out.

9. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 6, characterized in that, For the repair of cavities (2) in reservoirs with large irregular cavities (2) and high flow velocity and strong disturbance water environment, the step before S1 includes a step of setting a grouting reinforcement ring around the cavity (2). The grouting reinforcement ring is formed by grouting with magnetic grout (11) and the thickness of the reinforcement ring is 10~20cm. In S2, multiple grouting pipes (3) are used for synchronous grouting. The distance between adjacent grouting pipes (3) is 0.5~1.0m. The grouting sequence is from far to near.

10. The method for repairing cavities in a reservoir based on magnetic slurry according to claim 2, characterized in that, For repairing shallow, small-sized cavities (2) and cavities (2) in reservoirs with low-flow-rate water environments, the double-layer airbag (1) uses a micro-airbag with an outer diameter of 60% to 70% of the minimum inner diameter of the cavity (2); the grouting speed of S2 is 3 to 8 L / min; and S3 uses a troweling method to coat the cavity opening with magnetic grout (11) mixed with an accelerator, with a coating thickness of 5 to 10 cm.

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