Grouting and plugging method for lining construction of large-diameter pressure-bearing water delivery steel pipe

Abstract

The invention belongs to the technical field of steel pipeline lining construction, and particularly relates to a grouting and plugging method for large-diameter pressure-bearing water conveying steel pipe lining construction. The method comprises the steps that a grouting hole array and matched observation holes with the interval of 12-30 m are formed in the 12 o'clock direction of the top of a lining steel pipe, and an impact echo measuring area is established; the grouting pipe system in threaded connection is fixed to the grouting hole; the ratio of prepared water to cement to an expanding agent is 75: 120: 5, the density is 1.2-1.25 g / cm < 3 >, and the viscosity is greater than or equal to 25s; sequential grouting control is implemented, the grouting amount for the first time is 60% of the void volume, the grouting amount for the second time is 50% of the void volume, and the pressure is maintained to be 0.5-1.0 MPa; after grouting, matched steel plates are adopted for welding and hole sealing, and sealing assemblies with water stop flanges and spring compensation structures are arranged at the two ends. By optimizing hole position arrangement, dual-seal connection and pressure-flow cooperative control, the problems of hole position deviation, slurry segregation and sealing failure in a traditional process are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of steel pipeline lining construction technology, and particularly relates to a grouting and sealing method for the lining construction of large-diameter pressurized water transmission steel pipes. Background Technology

[0002] Traditional grouting techniques for steel pipe lining construction require pre-setting grouting holes during pipe fabrication and then sealing them with threaded connections after grouting. This method is suitable for lining construction scenarios where grouting holes are not critical. However, the pre-fabricated grouting holes may shift during pipe installation due to pipe rotation. To ensure the stability of large-diameter pressurized water supply steel pipes within the outer concrete casing and to prevent pipe movement caused by pressure changes during water supply, grouting is necessary after lining construction to fill the gap between the lining steel pipe and the concrete casing. Ideally, the grout should be completely sealed at the contact surface between the lining steel pipe and the concrete casing. High grout filling is required, and internal defect detection methods require at least three survey lines on the arch. Therefore, if the position of the grouting holes changes, it is difficult to ensure the arch is fully filled, rendering traditional grouting methods unsuitable. Summary of the Invention

[0003] The purpose of this invention is to provide a method for grouting and sealing the inner lining of large-diameter pressurized water supply steel pipes, which can ensure that the grout fills the gaps in the inner lining pipes evenly and avoid grouting blind spots.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for grouting and sealing the inner lining of a large-diameter pressurized water transmission steel pipe includes the following steps: S1. Pre-arrangement and opening: Grouting holes and observation holes are arranged and opened at the corresponding positions of the inner lining steel pipe. The grouting holes form an array along the preset positions of the inner lining steel pipe, and the observation holes are set according to the preset spacing. Valve components are installed on the grouting holes and observation holes. At the same time, an impact echo measurement area is established, and the measurement line is laid out along the preset orientation of the inner lining steel pipe to form an array of measurement points. S2. Assembly and fixing: Connect and assemble multiple grouting pipe units into a grouting pipe that is compatible with the inner steel lining pipe, and fix it at the grouting hole, with the pipe body arranged close to the top of the pipe. S3. Grouting Fluid Preparation: The raw materials for the grouting fluid are cement, fly ash slurry, and gypsum, with a mass ratio of water:fly ash:cement:gypsum = 100:80:17.5:2.5. The grouting fluid is then mixed using a pulping machine to form the grouting fluid. The density of the grouting fluid is controlled between 1.2 and 1.25 g / cm³. 3 The viscosity is above 25s; S4. Pressure and process control: During construction, monitor grouting pressure and pipeline deformation, control grouting pressure within the design range, and perform grouting in stages according to preset pressure and grouting volume. The first grouting is controlled by grouting volume, and the second grouting is controlled by both grouting pressure and grouting volume. Pressure holding and other operations are carried out during the grouting process. After the grouting is completed, a judgment is made and subsequent construction is carried out. S5. Sealing: After the grouting operation is completed, remove the valve components on the grouting hole and observation hole, and seal the grouting hole and observation hole with steel plate components that are compatible with the original pipeline. S6. End sealing: During grouting operations, sealing components are installed on both sides of the grouting pipe along the axial direction to achieve grouting sealing at both ends of the inner lining steel pipe.

[0005] Furthermore, in S1, grouting holes are arranged along the 12-point azimuth of the top of the inner lining steel pipe, with a spacing of 12-30m and a hole diameter of Φ40; observation holes are set at intervals of twice the grouting hole spacing; three axial measuring lines are evenly distributed at equal angles along the inner lining steel pipe at 30°-60° to the left and right in the impact echo measuring area, with a measuring line length of not less than 1.0m and not crossing the weld joint, a measuring point spacing of not more than 0.1m, and no less than 6 measuring points on each measuring line, which are arranged at equal intervals.

[0006] Furthermore, in S2, the grouting pipe unit uses Φ40 steel pipe with a wall thickness of 3.5mm, and is connected by threaded sleeves; when connecting the grouting pipe unit, edible grease is applied to the threaded part, and the pipe is tightened with pipe wrenches but not too forcefully; after threading the outer sides of both ends of the grouting pipe, edible grease is applied, and it is welded and fixed to the grouting hole, and the weld is reinforced.

[0007] Furthermore, in S3, the cement is 42.5 ordinary Portland cement, and / or the expansive agent may be one or more of alum stone expansive agent, calcium sulfoaluminate expansive agent, calcium oxide expansive agent, iron filings expansive agent, and calcium oxide-calcium sulfoaluminate composite expansive agent.

[0008] Furthermore, in S3, the alkali content of the expanding agent is no more than 0.75%, and the chloride ion content is no more than 0.05%. Furthermore, in S4, grouting is performed in two stages, with the total grouting volume controlled at 1.1 times the theoretical void volume; the theoretical void volume refers to the theoretical void volume between the inner wall of the culvert assembly and the outer wall of the inner lining steel pipe.

[0009] Furthermore, the two grouting operations are as follows: before grouting, close all valves, open the grouting holes in sequence, and after the grout is discharged from the observation hole, continue to open the grouting holes of the subsequent grouting holes until grout is sprayed through the observation holes on the water stop rings at both ends of the grouting pipe. Then close all valves and maintain pressure for 30 minutes. During the pressure maintenance period, the grouting pressure is maintained at 0.5~1.0MPa. The interval between the two grouting operations must ensure that the cement grout of the first grouting is completely solidified and maintained in a solidified state for at least 12 hours.

[0010] Furthermore, in S4, the first grouting volume is 60% of the theoretical void volume, and the second grouting volume is 50% of the theoretical void volume.

[0011] Furthermore, in S5, the thickness of the selected steel plate component is the same as the pipe wall thickness, and the size is determined according to the actual diameter of the grouting hole.

[0012] Furthermore, the sealing assembly in S6 comprises a culvert assembly, a first water-stop assembly, and a second water-stop assembly. The culvert assembly is a reinforced concrete culvert assembly sleeved on the outer sides of both axial ends of the inner steel liner. The first water-stop assembly includes two first water-stop flanges coaxially sleeved on the outer side of the inner steel liner, with an annular water-stop rubber ring filled between them and fixed to one end of the inner steel liner by expansion bolts. Multiple spring assemblies are evenly arranged circumferentially between them. The second water-stop assembly is a third water-stop flange connected to the end face of the culvert assembly by expansion bolts.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. Improve the quality and reliability of grouting construction. By setting an optimized array of grouting holes (spacing 12~30m) and an array of observation holes (spacing 24~60m) at 12 points on the top of the inner steel pipe, it is ensured that the grout fills the gaps in the inner steel pipe evenly and avoids grouting blind spots. The sequential pressure and flow rate coordinated control grouting technology (first grouting volume control + secondary grouting pressure / flow dual control) can accurately match the theoretical void volume (1.1 times), reducing grout waste while ensuring filling density; The impact echo detection system (3 axial measuring lines + high-density measuring point layout) monitors the grouting effect in real time, with a detection resolution of 0.1m, significantly reducing the risk of concrete voids. 2. Enhance pipeline structural stability: The special slurry formula, combined with fly ash additives, has a slurry density of 1.2~1.25 g / cm³. 3 With a viscosity ≥25s, it ensures fluidity while avoiding segregation; after void filling and crack repair, the grouting liquid diffuses and solidifies to fill the voids and cracks inside the water supply steel pipe, forming a high-strength reinforcement layer; experimental data show that the compressive strength of the water supply steel pipe increases by 30%-50% after reinforcement.

[0014] The double-sealed grouting pipe connection structure (threaded sleeve + edible oil seal + reinforced welding) enhances the pipeline's pressure-bearing capacity. The triple end sealing assembly (water-stop flange + rubber ring + spring compensation structure) enables dynamic adjustment of axial sealing pressure and can compensate for pipeline deformation and displacement. The steel-lined pipe repair technology uses an equal-diameter lining to fit the original pipe, avoiding the shrinkage problem of traditional grouting, and increasing the pressure-bearing capacity to 1.5 times that of the original pipe.

[0015] When using the steel plate sealing method, modular steel plate components that match the original pipeline material can be selected to quickly form a barrier in complex locations (such as crossing rivers or roads), which is especially suitable for emergency leakage scenarios.

[0016] 3. Good economic and social benefits: The segmented grouting process shortens the construction cycle of a single segment. In the repair of large-diameter pressurized water supply steel pipelines, traditional excavation takes several months, while the application of this method can shorten it to several weeks. Furthermore, the reliability of process connections was ensured through verification using test blocks cured under the same conditions; The JW350 mixer and wire mesh filter pulping system, combined with adaptive pressure regulation, effectively prevents pipe blockage accidents.

[0017] No need for large-scale ground excavation, reducing disruption to traffic, the surrounding environment, and residents' lives; Trenchless construction reduces the amount of earthwork transported (by about 70%) and avoids vegetation damage; some of the slurry can be mixed with industrial waste (such as fly ash) to reduce resource consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the installation of the first water-stopping component of the present invention; Figure 2 This is a schematic diagram of the installation of the second water-stopping component of the present invention; Figure 3 for Figure 2 The left view.

[0019] In the diagram: 1. Inner steel pipe; 2. Culvert assembly; 31. First water-stop flange; 32. Water-stop rubber ring; 33. Spring assembly; 34. First expansion bolt; 41. Second expansion bolt; 42. Second water-stop flange. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-3 As shown: This embodiment discloses a method for grouting and sealing the inner lining of a large-diameter pressurized water transmission steel pipe, including the following steps: S1. Grouting hole layout and opening: Grouting holes are drilled on-site. An array of grouting holes is established along the 12 o'clock position at the top of the inner lining steel pipe 1, with a spacing of a = 12~30m and a hole diameter of Φ40. An array of observation holes is set in the grouting holes, with one observation hole at a spacing of 2a. Valve components are installed on the grouting holes and observation holes. The inner lining steel pipe has the same inner and outer diameter as the original pressurized water supply steel pipe and is attached to one side of the original pressurized water supply steel pipe. Establish the impact echo measurement area: Three axial measurement lines are evenly distributed at equal angles (30°~60°) along the left and right sides of the inner lining steel pipe. The length of each measurement line L ≥ 1.0m and does not cross weld joints. The spacing between measurement points Δx ≤ 0.1m. Each measurement line should have no fewer than 6 measurement points, and they should be evenly spaced. S2. Grouting pipe connection and fixing: The grouting pipe is composed of multiple individual grouting pipes connected by threaded sleeves, and the total length matches the length of the inner steel lining pipe; each individual grouting pipe is made of Φ40 steel pipe with a wall thickness of 3.5mm. Specifically, when connecting individual grouting pipes, a suitable amount of edible grease should be applied to the threads for lubrication, protection, and sealing. Tighten with pipe wrenches, but do not use excessive force to prevent damage to the threads and slippage. After threading both ends of the grouting pipe, apply edible grease to the outer sides for lubrication and sealing. The grouting pipe is welded and fixed at the grouting hole. The weld seam needs to be reinforced to ensure the joint strength. The pipe body is arranged close to the top of the pipe. This part is existing technology and will not be described in detail here.

[0022] S3, Slurry ratio: The grouting fluid was determined based on on-site experiments. Multiple experiments showed that when the mass ratio of the grout was water: cement: expansion agent = 75: 120: 5, the grout could minimize concrete voids and reduce internal defects after solidification. In a further embodiment, the expansive agent may be one or more of the following: alum stone expansive agent, calcium sulfoaluminate expansive agent, calcium oxide expansive agent, iron filings expansive agent, and calcium oxide-calcium sulfoaluminate composite expansive agent. The chemical composition of the expansive agent should meet the relevant requirements in GB / T23439-2017 "Concrete Expansive Agents," with an alkali content not exceeding 0.75% and a chloride ion content not exceeding 0.05%. In a further embodiment, to ensure the stability of the inner steel pipe within the original concrete pipe, fly ash is also added to the grout. Fly ash is a type of artificial pozzolanic material. It has little or no hydraulic cementitious properties, but when present in powder form with water, it can chemically react with calcium hydroxide or other alkaline earth metal hydroxides at room temperature, especially under hydrothermal treatment (steam curing) conditions, to generate compounds with hydraulic cementitious properties, thus becoming a material that increases strength and durability.

[0023] Currently, fly ash is often used as an admixture in cement. The "ball-like" effect of fly ash particles can effectively improve the scalability of cement. The "volcanic ash" reaction of fly ash is relatively slow, which reduces the heat generated by hydration inside the cement. At the same time, the secondary hydration reaction of fly ash in the later stage of cement hydration (generally more than 28 days) can improve the density of concrete and reduce its permeability.

[0024] To ensure the stability of the steel lining pipe within the original concrete pipe, the grouting fluid is made from cement, fly ash slurry, and gypsum, with a mass ratio of water:fly ash:cement:gypsum = 100:80:17.5:2.5. P42.5° ordinary Portland cement is used. High-calcium fly ash is obtained from the combustion of lignite. Besides silica and alumina, it generally contains more than 10% calcium oxide and possesses a certain degree of hydraulicity. Because fly ash has a bulk density (apparent density) that is only about 2 / 3 that of cement and has a good particle shape, it can fill more densely; it can also physically disperse cement particles, making their distribution more uniform. Fly ash should meet the Class II requirements of the following standards:

[0025] Gypsum has a retarding effect; however, its strength increases rapidly in the later stages. Therefore, adding gypsum to cement slurry can meet both the strength requirements and ensure good injectability in the initial stage of slurry preparation. The gypsum used should be natural gypsum, conforming to Class G or Class A Grade II (inclusive) or higher as specified in GB / T5483. The fineness requirements should meet the standards for gypsum added to cement.

[0026] By setting the above parameters, the density of the grouting fluid is controlled between 1.2 and 1.25 g / cm³. 3 The viscosity should be controlled above 25s, and monitoring should be strengthened to ensure the quality of the mud.

[0027] S4. Slurry Preparation: A JW350 vertical mortar mixer is used as the slurry mixer, and the slurry volume is maintained at 2-3 ml. 3 The viscosity of the cement grout should be controlled on-site. The water content can be adjusted appropriately according to the grouting situation to prevent the grout from being thin at the top and thick at the bottom, which may cause pipe blockage. A wire mesh should be installed at the grout inlet to prevent large pieces of cement from entering the grouting pipe.

[0028] S5. Grouting pressure and process control: During construction, a designated person should monitor the grouting pressure and pipeline deformation to ensure that the grouting pressure is strictly controlled within the design pressure range. This will prevent over-grouting, which could cause pipeline deformation or instability. A pressure gauge should be used at the grouting hole to monitor the pressure value, and grouting should be stopped when the specified pressure is reached.

[0029] Sequential pressure-flow coordinated grouting: The grouting pressure is set to 0.5~1.0MPa; the total grouting volume is controlled at 1.1 times the theoretical void volume; the theoretical void volume refers to the theoretical void volume between the inner wall of the culvert assembly 2 and the outer wall of the inner lining steel pipe 1. In some specific embodiments, grouting is performed in two stages during construction. The first grouting volume is 60% of the theoretical void volume, with the grouting volume used as the control indicator. The second grouting volume is 50% of the theoretical void volume, with both grouting pressure and grouting volume controlled. A pressure gauge is used to monitor the pressure at the grouting hole; grouting is stopped immediately upon reaching the specified pressure. If the pressure reaches the design value during the second grouting but the grouting volume is insufficient, the grouting pressure can be increased. Before grouting, it must be ensured that the grouting pipe is completely filled with grout, and the second grouting volume must not be less than 0.35m. 3 / meter; Specifically, the two-stage grouting process is as follows: 1) Close all valves before grouting; 2) After starting grouting, first open the grouting holes of the first and second grouting pipe units. After the grout is discharged from the first set of observation holes, open the grouting holes of the third and fourth grouting pipe units, and so on, until grout is sprayed through the observation holes on the waterstop rings at both ends of the grouting pipe. 3) Close all valves and maintain pressure for 30 minutes, during which time the grouting pressure is maintained at 0.5~1.0MPa; Control of the interval between two grouting sessions: The interval between the first grouting and the second grouting is 2 to 5 days; if an accelerator is added to the grout, the interval can be shortened. The criteria for shortening the interval are as follows: the cement grout of the first grouting must be completely solidified and maintained in a solidified state for at least 12 hours. The solidification state is verified by test blocks cured under the same conditions. Grouting Completion Judgment and Subsequent Construction: Grouting is stopped when the grouting meets the design requirements; the observation hole is opened, and if there is grout spraying, it is judged as qualified, and then the grout inlet pipe interface is removed; Steps S2 to S5 are repeated in the next section of pipeline construction until the entire pipeline construction is completed; During the grouting process, the grouting pressure and pipeline deformation are monitored in real time by a dedicated person to ensure that the pressure is strictly controlled within the design range to prevent pipeline deformation or instability due to excessive grouting pressure; S6. Sealing of grouting holes After the grouting operation is completed and the grout reaches the predetermined solidification strength, the valve components installed on the grouting hole and observation hole are removed; steel plate components matching the original pipe material are selected to seal the grouting hole and observation hole; the steel plate components are fixed to the pipe material through welding; after the sealing operation is completed, the sealed area is internally ground to form a continuous and flat surface on the inner wall of the pipe; finally, anti-corrosion treatment is applied to the inner wall of the pipe; the working pit and receiving pit are backfilled, and the backfill surface is flush with the original ground.

[0030] In some embodiments, the thickness of the steel plate component is the same as the pipe wall thickness, and the size of the steel plate component is determined according to the actual diameter of the grouting hole.

[0031] In some embodiments, the sealing process further includes sealing the grouting hole and the observation hole using a threaded sealing structure.

[0032] S7. Grouting and sealing at both ends of the inner lining steel pipe. To prevent grout from overflowing from both sides of the grouting pipe, sealing components are installed on both sides of the grouting pipe during grouting operations: the sealing components include a reinforced concrete culvert assembly, a first water-stop assembly, and a second water-stop assembly, which are sleeved on the outer sides of both axial ends of the inner steel pipe. The first water-stopping assembly is connected between the culvert assembly 2 and the inner steel liner 1 to seal the gap between them; specifically, it includes two first water-stopping flanges 31 coaxially sleeved on the outside of the inner steel liner at certain intervals; a water-stopping rubber ring 32 is filled between the two first water-stopping flanges, and the first water-stopping flanges and the water-stopping rubber ring are fixed to one end of the inner steel liner by first expansion bolts 34. In some specific embodiments, multiple spring assemblies 33 are evenly arranged circumferentially between the two first water-stopping flanges.

[0033] The second water-stopping component is located at the end of the culvert assembly away from the first water-stopping component, and includes a second water-stopping flange 42 connected to the end face of the culvert assembly by a second expansion bolt 41.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for grouting and sealing the inner lining of a large-diameter pressurized water transmission steel pipe, characterized in that, Includes the following steps: S1. Pre-arrangement and opening: Grouting holes and observation holes are arranged and opened at the corresponding positions of the inner lining steel pipe. The grouting holes form an array along the preset positions of the inner lining steel pipe, and the observation holes are set according to the preset spacing. Valve components are installed on the grouting holes and observation holes. At the same time, an impact echo measurement area is established, and the measurement line is laid out along the preset orientation of the inner lining steel pipe to form an array of measurement points. S2. Assembly and fixing: Connect and assemble multiple grouting pipe units into a grouting pipe that is compatible with the inner steel lining pipe, and fix it at the grouting hole, with the pipe body arranged close to the top of the pipe. S3. Grouting Fluid Preparation: The raw materials for the grouting fluid are cement, fly ash slurry, and gypsum, with a mass ratio of water:fly ash:cement:gypsum = 100:80:17.5:2.

5. The mixture is then stirred using a slurry mixer to form the grouting fluid. The density of the grouting fluid is controlled between 1.2 and 1.25 g / cm³. 3 The viscosity is above 25s; S4. Pressure and process control: During construction, monitor grouting pressure and pipeline deformation, control grouting pressure within the design range, and perform grouting in stages according to preset pressure and grouting volume. The first grouting is controlled by grouting volume, and the second grouting is controlled by both grouting pressure and grouting volume. Pressure holding and other operations are carried out during the grouting process. After the grouting is completed, a judgment is made and subsequent construction is carried out. S5. Sealing: After the grouting operation is completed, remove the valve components on the grouting hole and observation hole, and seal the grouting hole and observation hole with steel plate components that are compatible with the original pipeline. S6. End sealing: During grouting operations, sealing components are installed on both sides of the grouting pipe along the axial direction to achieve grouting sealing at both ends of the inner lining steel pipe.

2. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 1, characterized in that: In S1, grouting holes are arranged along the 12-point azimuth of the top of the inner steel pipe, with a spacing of 12~30m and a hole diameter of Φ40; observation holes are set at intervals of twice the grouting hole spacing; three axial measuring lines are evenly distributed at equal angles along the inner steel pipe at 30°~60° to the left and right of the impact echo measuring area, with a measuring line length of not less than 1.0m and not crossing the weld joint, a measuring point spacing of not more than 0.1m, and no less than 6 measuring points on each measuring line, which are arranged at equal intervals.

3. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 1, characterized in that: In S2, the grouting pipe unit is made of Φ40 steel pipe with a wall thickness of 3.5mm, and is connected by threaded sleeves. When connecting the grouting pipe unit, edible grease is applied to the threaded part, and the pipe is tightened with pipe wrenches but not too forcefully. After threading the outer sides of both ends of the grouting pipe, edible grease is applied, and it is welded and fixed to the grouting hole, and the weld is reinforced.

4. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 1, characterized in that: In S3, the cement is 42.5 ordinary Portland cement, and / or the expansive agent may be one or more of the following: alum stone expansive agent, calcium sulfoaluminate expansive agent, calcium oxide expansive agent, iron filings expansive agent, and calcium oxide-calcium sulfoaluminate composite expansive agent.

5. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 4, characterized in that: In S3, the alkali content of the expanding agent is no more than 0.75%, and the chloride ion content is no more than 0.05%.

6. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 1, characterized in that: In S4, grouting is performed in two stages, with the total grouting volume controlled at 1.1 times the theoretical void volume. The theoretical void volume refers to the theoretical void volume between the inner wall of the culvert assembly and the outer wall of the inner lining steel pipe.

7. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 6, characterized in that: The procedure for the two grouting operations is as follows: before grouting, close all valves, open the grouting holes in sequence, and after the grout is discharged from the observation hole, continue to open the grouting holes of the subsequent grouting holes until the grout is sprayed through the observation holes on the water stop rings at both ends of the grouting pipe. Then close all valves and maintain pressure for 30 minutes. During the pressure maintenance period, the grouting pressure is maintained at 0.5~1.0MPa. The interval between the two grouting operations must ensure that the cement grout of the first grouting is completely solidified and maintained in a solidified state for at least 12 hours.

8. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 6, characterized in that: The first grouting volume is 60% of the theoretical void volume, and the second grouting volume is 50% of the theoretical void volume.

9. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 1, characterized in that: In S5, the thickness of the selected steel plate component is the same as the pipe wall thickness, and the size is determined according to the actual diameter of the grouting hole.

10. The grouting process for the inner lining of large-diameter pressurized water conveyance steel pipelines according to claim 1, characterized in that: The sealing assembly in S6 consists of a culvert assembly, a first water-stop assembly, and a second water-stop assembly. The culvert assembly is a reinforced concrete culvert assembly that is sleeved on the outer side of both axial ends of the inner steel liner. The first water-stop assembly includes two first water-stop flanges that are coaxially sleeved on the outer side of the inner steel liner, with an annular water-stop rubber ring between them and fixed to one end of the inner steel liner by expansion bolts. Multiple spring assemblies are evenly arranged circumferentially between them. The second water-stop assembly is a third water-stop flange that is sealed and connected to the end face of the culvert assembly by expansion bolts.

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