Underwater butt joint reinforcing method in high water pressure permeable stratum

Abstract

The application provides an underwater butt joint reinforcement method in a high water pressure and strong permeation stratum, relates to the field of shield construction, is suitable for underwater butt joint engineering of two large-diameter shield machines, has high safety for high water pressure and strong permeation strata, effectively meets special working conditions of limited underwater construction space, and specifically comprises the following steps: step 1, a plurality of radial grouting holes are arranged in a middle shield of the shield machine, a water stop curtain is formed around the shield machine through radial grouting, and a closed construction environment is provided for subsequent construction; step 2, a plurality of groups of inclined grouting holes are pre-buried on the shield shell, advanced grouting reinforcement is carried out, and the stratum is improved to facilitate the formation of a frozen wall; step 3, after the advanced grouting is completed, a freezing pipe is inserted into the inclined grouting hole to carry out freezing reinforcement; step 4, a pressure relief hole is reserved on the shield machine, the pressure relief hole is inclined through a shield air bubble bin, and the pressure relief hole is used to control the frost heaving force and the frost heaving amount; and step 5, after the freezing is completed, whether water leakage occurs is observed through the pressure relief hole to detect the freezing quality.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring machine (TBM) construction, specifically a method for underwater docking and reinforcement in high-water-pressure, highly permeable strata. Background Technology

[0002] Currently, the trends in large-diameter shield tunnel construction in China are: from single soft soil strata to complex strata; from large diameter to ultra-large diameter; from medium water pressure to high and ultra-high water pressure; from medium-intensity seismic zones to high-intensity seismic zones; from single-mode shield tunneling to multi-mode shield tunneling; from single construction methods to combinations of multiple methods; from traditional construction management to digital management; and from short-distance tunneling to long-distance and ultra-long-distance tunneling. With the acceleration of urbanization and inter-city development in my country, and the construction of cross-strait tunnels on the agenda, more underwater tunnel projects will be built in areas with complex river, lake, and sea environments. Shield tunnels longer than 30 kilometers face significant technical challenges and environmental issues if island-building is carried out in the middle of a strait for receiving tunnels. Underwater shield docking provides a feasible solution for such projects.

[0003] Whether the strata can be effectively reinforced and reliably supported determines whether the shield tunnel can be successfully docked. This is especially critical for assisted docking. The backward docking technology, which focuses on reinforcement and support at the docking point, has been hindering the development of ultra-long shield tunnels.

[0004] After the tunnel boring machines (TBMs) are docked, the pressure inside the slurry chamber or earth pressure chamber is lost. Since there is inevitably a gap between the shields of the two TBMs, the contact surface at the docking point is connected to the external strata and directly exposed to the external environment. Before constructing the internal tunnel structure, the internal structure and cutterhead of the TBMs must be disassembled. With the loss of internal support, the cutterheads can no longer provide support against external water and soil pressure, and the entire tunnel becomes connected to the external strata, posing an extremely high risk.

[0005] There are several successful examples of shield tunneling docking abroad. In Japan, over a dozen projects, including the Tokyo Bay Cross-Road Tunnel, the Tokyo Bay Gas Central Trunk Tunnel, the Ise Bay Gas Tunnel, and the Kawasaki Artificial River Tunnel, have all employed shield tunneling docking. Domestically, research on shield tunneling docking is deepening, and its application in practical engineering is gradually increasing. The Shiziyang Tunnel on the Guangzhou-Shenzhen-Hong Kong Express Rail Link is currently the only tunnel in China constructed using shield tunneling docking technology. Due to its location in slightly weathered rock strata, chemical grouting was used to reinforce the rock strata at the docking location. The docking design of the Jintang Subsea Tunnel on the Ningbo-Zhoushan Railway is similar to that of the Shiziyang Tunnel, both employing grouting reinforcement, but construction has not yet commenced. Currently, only the Qiongzhou Strait Tunnel shield tunneling docking project has conducted preliminary research on ground freezing reinforcement for shield tunneling docking; there are no other engineering examples of its application in China. The burial depth of ultra-large diameter shield tunnels generally exceeds 20 meters, and underwater tunnels crossing rivers and seas also face extremely high water depths. The shield shell interface bears enormous water and soil loads. Without support measures, soil and water inrush can easily occur, damaging the tunnel structure and causing major safety accidents. Therefore, it is necessary to reinforce the soil outside the shield docking location to withstand external water and soil pressure, while isolating the construction environment from external hydraulic contact to create stable construction conditions.

[0006] The field of underwater shield tunneling is still in its early stages, both domestically and globally. When the shield tunnel docking location is in a high-pressure, highly permeable underwater stratum, the risk of freezing construction in sandy soil containing confined water is high. Traditional grouting reinforcement methods are difficult to implement and achieve the desired results. In such cases, freezing methods must be used for pre-reinforcement of the docking section. However, high-pressure, highly permeable underwater strata pose a significant challenge to freezing reinforcement, especially when the superimposed water flow velocity is high or the internal temperature of the shield is high, drastically increasing the difficulty of ensuring safety.

[0007] For pre-reinforcement during shield tunnel docking construction, existing domestic cases involve grouting, a technique primarily suitable for rock formations with low permeability and good self-stabilizing capacity. However, for river-crossing tunnels potentially encountering high-water-pressure, highly permeable strata, simple grouting is insufficient to achieve the desired reinforcement effect and cannot guarantee water-stopping performance. In such cases, freezing reinforcement becomes necessary. However, there are no similar engineering cases, domestic or international, of freezing reinforcement for shield docking sections in high-water-pressure, highly permeable strata. Existing freezing reinforcement techniques in the literature present the following main problems for high-water-pressure, highly permeable strata:

[0008] (1) There is currently no advanced freezing reinforcement construction technology for the docking of ultra-large diameter shield tunnels in high water pressure and strong permeability strata;

[0009] (2) Due to the high water pressure and strong seepage conditions underwater, and the presence of groundwater flow, the quality requirements for freezing reinforcement are relatively high. Existing freezing reinforcement measures such as connecting passages only use individual freezing measures, which makes it difficult to ensure the formation of a reliable frozen wall under the high water pressure and strong seepage environment underwater.

[0010] (3) When in an underwater environment, it is not possible to reinforce and freeze from the ground. Reinforcement and freezing need to be carried out from inside the tunnel. However, the current conventional layout of the tunnel boring machine is not conducive to drilling grouting holes, freezing holes, temperature measuring holes and pressure relief holes inside the tunnel (on the shield shell of the tunnel boring machine). Targeted modifications to the tunnel boring machine are required.

[0011] (4) Existing freezing reinforcement technology can achieve the purpose of freezing reinforcement by using only one freezing method. However, in the complex underwater environment of ultra-large diameter shield tunnels, the water pressure is high and the permeability is strong. Once a dangerous situation occurs, it will be difficult to remedy.

[0012] (5) Unlike conventional communication channels and shield receiving and starting freezing cases, after the shield machines are docked, it is necessary to dismantle the internal components of the shield machines and weld the two shield machines together. The cutting and welding operations generate a lot of heat, and the shield shell is a good heat conductor, which can easily transfer the cutting and welding heat and even the ambient temperature inside the tunnel to the frozen soil layer, causing the soil layer at the interface between the shield shell and the frozen body to melt and form a seepage channel. Summary of the Invention

[0013] The purpose of this invention is to address the aforementioned problems and shortcomings of the existing technology by designing an underwater docking reinforcement method for high water pressure and strong permeability strata. This method is applicable to underwater docking projects of two large-diameter tunnel boring machines and offers high safety for high water pressure and strong permeability strata, effectively meeting the special working conditions of limited underwater construction space.

[0014] A method for underwater docking reinforcement in high water pressure and highly permeable formations includes the following steps:

[0015] Step 1: Set no less than one ring of radial grouting holes in the shield of the tunnel boring machine. Through radial grouting, a water-stop curtain is formed around the shield, providing a closed construction environment for subsequent advanced grouting and freeze reinforcement.

[0016] Step 2: Multiple sets of inclined grouting holes are pre-embedded on the shield shell. The inclined grouting holes also serve as freezing holes. Each set of inclined grouting holes points towards the shield docking direction. After removing the shield machine jacks and hydraulic shield machine components, a working space is established. Advanced grouting pipes are inserted into the inclined grouting holes to carry out advanced grouting reinforcement, improve the stratum, reduce the stratum permeability coefficient, increase the stratum strength, so as to facilitate the formation of the frozen wall and reduce the frost heave and thaw settlement effect.

[0017] Step 3: After the pre-grouting is completed, insert a freezing pipe into the grouting hole at an angle to carry out freezing reinforcement work;

[0018] Step 4: Reserve pressure relief holes on the tunnel boring machine. The pressure relief holes obliquely pass through the air bubble chamber of the tunnel boring machine. The pressure relief holes are used to control the frost heave force and the amount of frost heave.

[0019] Step 5: After freezing is complete, check for water leakage through the pressure relief hole to test the freezing quality. If there is no water leakage, proceed with the subsequent work of cleaning the mortar, cutting the cutter head and blades, and removing the air bubbles from the mud and water chamber walls.

[0020] Preferably, in step 1, the reserved radial grouting holes are reserved according to the final hole spacing not exceeding twice the grout diffusion radius, so as to ensure that the grouting can be completed in a loop to form a closed water-stop curtain.

[0021] Preferably, multiple radial grouting holes are pre-drilled on the inner radial side of the shield shell in the tunnel boring machine. These radial grouting holes are sealed with screws. The screw heads have a flat, raised section. The thread length of the screw is equal to the length of the radial grouting hole. The total height of the screw head and the flat, raised section is less than 5 cm to ensure that the screw head protrudes slightly above the shield shell, thus not affecting the layout of other internal components of the tunnel boring machine.

[0022] Weld orifice pipes to the radial grouting holes and connect them to ball valves. A sealing box is installed below the ball valve. After sealing, the screws are loosened using a threaded rod. The top of the threaded rod has a slotted groove that matches a protruding inline shape.

[0023] The screw removal process involves two steps. First, the screw is pulled out to the outside of the ball valve and inside the sealing box; at this point, the ball valve is closed to stop the water flow. Second, the screw is pulled out of the sealing box, ensuring the hole is sealed when the screw is unscrewed and preventing the risk of water or sand inrush.

[0024] The radial grouting pipe is inserted in two steps. The first step is to insert it to the outside of the ball valve and seal it with the sealing box. Then, the ball valve is opened and the radial grouting pipe is drilled into the designed depth of the formation. Grouting operations are then carried out to ensure the sealing of the radial grouting pipe during insertion and to avoid the risk of water and sand inrush during the insertion of the radial grouting pipe.

[0025] Preferably, a groove is provided next to the slotted groove at the top of the screw, which is connected to the slotted groove. An electromagnet is installed in the groove. After the slotted protrusion and the slotted groove are engaged, the power supply to the electromagnet is turned on, and the screw is turned counterclockwise. The screw drives the screw away from the orifice tube until the screw is pulled out. The electromagnet is kept energized to ensure that the screw and the screw are fastened and will not fall out during the extraction process.

[0026] Preferably, each row of inclined grouting holes is arranged radially outward from the shield at a certain angle, and the distance between any two adjacent inclined grouting holes in each row is no more than 1m, so as to ensure that the final hole spacing is less than 1.5m, thereby meeting the requirements for grouting pipe spacing and freezing final hole spacing.

[0027] Preferably, the freezing pipe is drilled using a coring drill bit, and the freezing pipe is inserted after coring to ensure that the drilling does not deviate when there are uneven formations after grouting, thus ensuring the drilling accuracy of the freezing pipe.

[0028] Preferably, the grouting material for radial grouting and pre-grouting is single-liquid ultrafine cement grout, and the grouting pressure is controlled at 0.8-1 MPa higher than the water pressure at the joint, so as to avoid excessive grouting pressure load from having an adverse effect on the shield shell.

[0029] Preferably, the pressure relief hole extends from the cut ring and contacts the formation. The circumferential distance between two adjacent pressure relief holes is no more than 2m, thereby ensuring that the pressure relief hole can uniformly cover the area to be frozen, ensuring uniform and timely pressure relief of the area to be frozen, reducing the amount of frost heave. A ball valve is installed at the tail of the pressure relief hole to seal it and a pressure gauge is set.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The purpose of this invention is to address the aforementioned problems and shortcomings of the existing technology by designing an underwater docking reinforcement method for high water pressure and strong permeability strata. This method is applicable to underwater docking projects of two large-diameter tunnel boring machines and offers high safety for high water pressure and strong permeability strata, effectively meeting the special working conditions of limited underwater construction space.

[0032] 1. This invention improves the surrounding highly permeable soil by pre-reserving radial grouting holes and advanced grouting holes on the shield shell of the tunnel boring machine after the tunnel boring machine reaches the docking position, forming a grouting-reinforced water-stopping curtain, reducing the stratum permeability coefficient and groundwater flow, and improving and ensuring the freezing effect.

[0033] 2. The grouting slurry of this invention uses ultrafine cement slurry, which is beneficial to improve the diffusion range of the slurry and improve the grouting effect. At the same time, it does not affect the heat conduction of freezing. The permeability coefficient of the reinforced soil is reduced and the strength is increased, which can reduce the groundwater flow rate and reduce the impact of frost heave and thaw settlement.

[0034] 3. This invention provides a method for reserving radial grouting holes and advanced grouting holes that also serve as freezing holes, temperature measuring holes, and pressure relief holes for ultra-large diameter shield tunneling machines. It also provides a safe and efficient method for drilling holes, which can effectively solve the risks of drilling freezing holes in shield shells in high water pressure and highly permeable strata, and can improve work efficiency.

[0035] 4. The present invention pre-installs advanced grouting holes on the tunnel boring machine, which also serve as freezing holes, thereby reducing the impact of the number of holes on strength, ensuring the safety of the construction process, and effectively improving construction efficiency.

[0036] 5. The pre-drilled holes in this invention are sealed with screws to reduce the height of the pre-drilled holes protruding from the shield shell, thus not affecting the layout and installation of internal components of the tunnel boring machine.

[0037] 6. This invention provides a method for unscrewing a pre-drilled bolt in a closed state, which can safely open the pre-drilled bolt and prevent water and sand from flowing in.

[0038] 7. This invention provides a reinforcement method that combines grouting and freezing. Grouting is performed using freezing holes to reinforce and improve unfavorable hydrogeological conditions at the joint. This can reduce the groundwater flow rate and porosity at the joint, reduce frost heave and thaw settlement caused by freezing, and improve the freezing quality. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the radial pre-reserved hole sealing design of the present invention;

[0040] Figure 2 The radial pre-drilled hole drilling steps designed for this invention Figure 1 ;

[0041] Figure 3 This is a detailed drawing of the end of the cross-shaped force-adding screw designed for this invention;

[0042] Figure 4 The radial pre-drilled hole drilling steps designed for this invention Figure 2 ;

[0043] Figure 5 This is a schematic diagram of the grouting pipe insertion steps designed for this invention;

[0044] Figure 6 This is a schematic diagram of the radial grouting range designed for this invention;

[0045] Figure 7 This is a schematic diagram of the reserved hole for the docking shield machine designed for this invention;

[0046] Figure 8 A schematic diagram of the pre-reserved oblique advanced grouting hole / freezing hole designed for this invention;

[0047] Figure 9 This is a schematic diagram of the advanced grouting range designed for this invention;

[0048] Figure 10 This is a schematic diagram of the grouting + freezing combined reinforcement range designed in this invention. Detailed Implementation

[0049] The following description, in conjunction with the accompanying drawings and specific implementation methods, provides a more detailed explanation of the underwater docking reinforcement method for high water pressure and high permeability formations according to the present invention.

[0050] First, radial grouting holes and advanced grouting holes are pre-set on the tunnel boring machine.

[0051] The tunnel boring machine (TBM) has at least one row of radial grouting pipes pre-installed in the shield. Through radial grouting, a water-stop curtain is formed around the TBM, creating a relatively closed construction environment for subsequent pre-grouting and freeze-thaw reinforcement. The pre-reserved radial grouting holes are spaced no more than twice the grout diffusion radius to ensure the grouting can complete a loop and form a closed water-stop curtain. The diameter of the pre-reserved radial grouting pipes is no less than 60mm, and the pre-reserved grouting holes are sealed with screws. When using screws for sealing, the distance above the shield shell is small, which does not affect the layout of other internal components of the TBM. Figure 1 As shown.

[0052] Before opening the pre-reserved hole, weld a borehole pipe to the pre-reserved hole and connect a ball valve and a sealing box. The borehole pipe is used to ensure a tight seal when opening the hole. The grouting pipe or freezing pipe is inserted through the borehole pipe and extends into the formation. The borehole pipe and sealing box are used to ensure the sealing of the grouting pipe or freezing pipe when it is inserted into the formation, preventing water leakage.

[0053] After the sealing box is sealed by inserting a specially designed screw into the orifice tube, the reserved screw is unscrewed using the screw.

[0054] The screw thread length is set according to the required hole length, and an end cap is set to prevent it from protruding outside the shield shell;

[0055] Next to the slot at the top of the screw is a groove that communicates with the slot, and an electromagnet is installed in the groove, such as... Figure 2 and Figure 3 As shown, after the straight protrusion and the straight slot are engaged, the electromagnet power is turned on, and the screw is turned counterclockwise. The screw drives the screw away from the orifice tube until the screw is pulled out. The electromagnet remains energized to ensure that the screw and the screw are fastened and will not fall out during the extraction process.

[0056] The screw removal process involves two steps. First, pull it out to the outside of the ball valve and inside the sealing box; at this point, the ball valve can be closed to stop the water flow. Second, pull the screw out of the sealing box, as shown below. Figure 4 and Figure 5 As shown.

[0057] The radial grouting pipe insertion also involves two steps. First, it is inserted to the outside of the ball valve and sealed with the sealing box. Then, the ball valve is opened, and the grouting pipe is drilled to the designed depth in the formation before grouting operations commence. The grouting range is as follows: Figure 6 As shown.

[0058] The shield shell has pre-embedded oblique grouting holes, which also serve as freezing holes. The locations of the pre-reserved holes are as follows: Figure 7As shown. The spacing between any two adjacent inclined grouting holes in each row should not exceed 1m to ensure that the final hole spacing is less than 1.5m, thus meeting the requirements for grouting pipe spacing and freezing final hole spacing. Here, the starting position is along the shield shell circumference, and the ring at the final hole position is larger than the shield shell ring, hence the final hole spacing will be larger. Two to three rows of inclined grouting holes are set on each side of the docking shield machine. The inclined grouting pipes or freezing pipes are installed from the shield shell at a fixed angle, such as 15°-30°, in the inclined docking direction. Due to the radial arrangement, the shield shell position serves as the starting position with the minimum spacing, and the other end is the final hole. As the length of the grouting pipe increases, the distance between the final holes will increase. The goal is to ensure that even the maximum spacing remains within the grout diffusion range.

[0059] The structure below the inclined grouting hole is consistent with that of the radial grouting pipe. Unscrew the screws of the inclined grouting hole; the opening sequence is consistent with that of the radial grouting pipe. Figure 8 As shown.

[0060] At the inclined grouting hole of the shield, an advanced grouting pipe is inserted to carry out advanced grouting reinforcement and improve the stratum;

[0061] The grouting slurry is a single-component ultrafine cement slurry, and the grouting pressure is 0.8-1.0 MPa higher than the water pressure at the connection point. The highly permeable strata at the shutdown location are improved to reduce the stratum permeability coefficient, thus facilitating the formation of a frozen wall. The grouting reinforcement diffusion radius is not less than 60 cm, forming a reinforced water-stop curtain within the shield machine connection area. The advance grouting range is as follows: Figure 9 As shown.

[0062] After grouting, some internal components of the tunnel boring machine, such as jacks and hydraulic cylinders, are removed to create space for the pre-reserved freezing holes. Freezing pipes are then inserted for freezing reinforcement. The freezing reinforcement area is as follows: Figure 10 As shown.

[0063] After grouting, due to the discreteness of the grouting effect, the formation may have uneven hardness. In order to ensure the drilling accuracy of the freezing pipe and prevent deviation, the freezing pipe is drilled with a core drill bit, and the core is inserted into the freezing pipe after core extraction to ensure the laying accuracy of the freezing pipe.

[0064] Next, pressure relief holes are pre-installed on the tunnel boring machine, obliquely passing through the bubble chamber. At the point where the hole extends out from the cut ring, it contacts the ground, with a circumferential spacing of no more than 2 meters. A ball valve is installed at the tail of the pressure relief hole to seal it, and a pressure gauge is set there. The pressure relief holes are used to control frost heave force and frost heave amount.

[0065] After freezing, use the pressure relief hole to check for leaks. If there are no leaks, proceed with subsequent work such as mortar cleaning, cutting of the cutter head and blades, and removal of the air bubble chamber wall panels.

[0066] At the same time, it is also necessary to pre-install freezing temperature measurement holes on the shield shell of the tunnel boring machine to monitor the temperature changes of the frozen body.

[0067] Current standards and manuals generally recommend that when groundwater flow velocities exceed 2 m / d, in confined aquifers, or in frozen river or lake locations, targeted reinforcement measures are necessary to ensure effective freezing. For underwater shield tunneling docking projects, radial and pre-drilled grouting holes are pre-drilled on the shield shell. After the shield reaches the docking position, the surrounding highly permeable soil is improved, forming a grout-reinforced water-stopping curtain. This reduces the permeability coefficient of the formation and the flowability of groundwater, thereby improving and ensuring the freezing effect. The grouting material is single-component ultrafine cement grout, and the grouting pressure is controlled at 0.8~1 MPa higher than the water pressure at the docking point.

[0068] When ultra-large diameter tunnel boring machines (TBMs) are located underwater, the geological strata are often high-water-pressure and highly permeable. In such environments, drilling holes in the shield shell to create freezing ports carries a high risk of water and sand inrush, and drilling through the thick shield shell at an angle requires a considerable amount of time. The pre-drilled holes in the shield shell of this invention can effectively solve the risks of drilling freezing ports in high-water-pressure and highly permeable strata and improve work efficiency.

[0069] This invention proposes an underwater docking reinforcement method for high-pressure, highly permeable formations. The above embodiments are only for illustrating the technical concept and features of this invention, and are intended to enable those skilled in the art to understand the content of this invention and implement it accordingly. They should not be construed as limiting the scope of protection of this invention. All equivalent changes or modifications made according to the spirit and essence of this invention should be covered within the scope of protection of this invention.

Claims

1. A method for underwater docking reinforcement in high water pressure and high permeability formations, characterized in that, Includes the following steps: Step 1: Set no less than one ring of radial grouting holes in the shield of the tunnel boring machine. Through radial grouting, a water-stop curtain is formed around the shield, providing a closed construction environment for subsequent advanced grouting and freeze reinforcement. Step 2: Multiple sets of inclined grouting holes are pre-embedded on the shield shell. The inclined grouting holes also serve as freezing holes. Each set of inclined grouting holes points towards the shield docking direction. After dismantling the shield machine trolley, assembly machine, jacks and hydraulic cylinder components, a working space is established. Advanced grouting pipes are inserted into the inclined grouting holes to carry out advanced grouting reinforcement, improve the stratum, reduce the stratum permeability coefficient, increase the stratum strength, so as to facilitate the formation of the frozen wall and reduce the frost heave and thaw settlement effect. Step 3: After the pre-grouting is completed, insert a freezing pipe into the grouting hole at an angle to carry out freezing reinforcement work; Step 4: Reserve pressure relief holes on the tunnel boring machine. The pressure relief holes obliquely pass through the air bubble chamber of the tunnel boring machine. The pressure relief holes are used to control the frost heave force and the amount of frost heave. Step 5: After freezing is complete, check for water leakage through the pressure relief hole to test the freezing quality. If there is no water leakage, proceed with the subsequent work of cleaning the mortar, cutting the cutter head and blades, and removing the air bubbles in the mud and water chamber. The radial grouting hole is sealed with a screw. The screw head has a flat protrusion, and the top of the screw has a groove next to the flat slot that is connected to the flat slot. An electromagnet is installed in the groove. After the flat protrusion and the flat slot are engaged, the electromagnet is powered on and the screw is turned counterclockwise. The screw drives the screw away from the hole tube until the screw is pulled out. The electromagnet is kept energized to ensure that the screw and the screw are fastened and will not fall out during the extraction process.

2. The underwater docking reinforcement method for high water pressure and high permeability formations according to claim 1, characterized in that: In step 1, the radial grouting holes are reserved according to the size of no more than twice the grout diffusion radius to ensure that the grouting can be completed in a loop to form a closed water-stop curtain.

3. The underwater docking reinforcement method for high water pressure and high permeability formations according to claim 2, characterized in that: Multiple radial grouting holes are pre-drilled on the inner radial side of the shield shell in the tunnel boring machine. The thread length of the screw is equal to the length of the radial grouting hole, and the total height of the screw head and the slotted protrusion is less than 5cm to ensure that the screw head protrudes only slightly from the shield shell and does not affect the layout of other internal components of the tunnel boring machine. Weld orifice pipes to the radial grouting holes and connect them to ball valves. A sealing box is installed below the ball valve. After sealing, the screws are loosened using a threaded rod. The top of the threaded rod has a slotted groove that matches a protruding inline shape. The screw removal process involves two steps. First, the screw is pulled out to the outside of the ball valve and inside the sealing box; at this point, the ball valve is closed to stop the water flow. Second, the screw is pulled out of the sealing box, ensuring the hole is sealed when the screw is unscrewed and preventing the risk of water or sand inrush. The radial grouting pipe is inserted in two steps. The first step is to insert it to the outside of the ball valve and seal it with the sealing box. Then, the ball valve is opened and the radial grouting pipe is drilled into the designed depth of the formation. Grouting operations are then carried out to ensure the sealing of the radial grouting pipe during insertion and to avoid the risk of water and sand inrush during the insertion of the radial grouting pipe.

4. The underwater docking reinforcement method for high water pressure and high permeability formations according to claim 1, characterized in that: Each row of inclined grouting holes is arranged radially outward from the shield at a certain angle. The distance between any two adjacent inclined grouting holes in each row is no more than 1m to ensure that the final hole spacing is less than 1.5m, thereby meeting the requirements for grouting pipe spacing and freezing final hole spacing.

5. The underwater docking reinforcement method for high water pressure and high permeability formations according to claim 1, characterized in that: The freezing pipe is drilled using a coring drill bit. After coring, the freezing pipe is inserted to ensure that the drilling does not deviate even when the formation has uneven hardness after grouting, thus ensuring the drilling accuracy of the freezing pipe.

6. The underwater docking reinforcement method for high water pressure and high permeability formations according to claim 1, characterized in that: The grouting material for radial grouting and pre-grouting is single-liquid ultrafine cement grout. The grouting pressure is controlled at 0.8-1 MPa higher than the water pressure at the joint, so as to avoid excessive grouting pressure load from having an adverse effect on the shield shell.

7. The underwater docking reinforcement method for high water pressure and high permeability formations according to claim 1, characterized in that: The pressure relief hole extends from the cut ring and contacts the formation. The circumferential distance between two adjacent pressure relief holes is no more than 2m, so as to ensure that the pressure relief hole can evenly cover the area to be frozen, and ensure that the pressure can be evenly and timely relieved in the area to be frozen, thereby reducing the amount of frost heave. A ball valve is installed at the tail of the pressure relief hole to seal it and a pressure gauge is set there.

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