A frozen-based advanced pre-grouting anti-run method for large-dip-angle strata

Abstract

This invention discloses a method for preventing grout leakage in steeply dipping formations through pre-grouting based on freezing. It employs a borehole water-freezing process, freezing is carried out at a suitable location in the stratum based on the dip angle and the spatial morphology and location of the target area, forming a frozen grout leakage prevention curtain. This prevents grout from overflowing to the surface or into ineffective formation spaces without altering its fluidity, ensuring sufficient filling of formation fractures in the target area. This invention is a proactive method for preventing grout leakage by utilizing a frozen curtain to prevent grout from overflowing to the surface or into distant ineffective spaces along steeply dipping formation fractures. It effectively controls the direction and distance of grout diffusion, reduces ineffective grout migration, and improves the impermeability of the curtain and the effectiveness of curtain grouting.

Description

Technical Field

[0001] This invention belongs to the field of water control technology for underground excavation construction structures, specifically relating to a method for preventing grout leakage by pre-grouting in frozen, steeply inclined strata. Background Technology

[0002] When tunneling underground structures in steeply inclined strata, if the aquifer in the working stratum has a large water volume and high recharge intensity, which may cause water inrush at the working face, curtain grouting can be carried out in the aquifer outside the structure to form a water-proof curtain in the stratum space, which will laterally block the stratum water outside the curtain and allow the groundwater to flow around it, thereby ensuring safe production at the working face in a waterless or low-water environment.

[0003] The key to preventing grout leakage in curtain grouting is effectively controlling the direction and distance of grout diffusion, especially in water-rich strata with steep dips. This ensures the grout can overlap and form a complete curtain wall. If the grout overflows along the dominant fracture channels of the stratum dip angle, complete overlap between adjacent grouting holes cannot be guaranteed, leaving weak points and causing leaks in the curtain. Ground water on the outside of the curtain can penetrate through these weak points and enter the inside. The longer the curtain, the more weak points it has, significantly reducing its seepage prevention capacity and failing to achieve the expected water-proofing effect.

[0004] Conventional methods for preventing grout leakage in grouting curtain engineering include changing the grout concentration, intermittent grouting, changing the grout type, and adding aggregates to the grout. However, due to the complexity, non-uniformity, and uncertainty of the fractures in the pre-grouting strata, the pressurized grout often migrates along the dominant fracture channels in steeply dipping strata, causing it to overflow onto the ground or spill into ineffective spaces far from the pre-grouting strata. Even adjusting the grout concentration, adopting intermittent grouting, changing the grout type, or adding aggregates to the grout cannot effectively prevent the grout from migrating and spreading along the dominant fracture channels, thus failing to achieve the desired grout leakage prevention effect, resulting in significant grout waste and increased construction costs. Therefore, traditional measures such as changing the grout concentration, intermittent grouting, changing the grout type, and adding aggregates to the grout are not only cumbersome and costly, but also inconvenient in terms of material sourcing, pollute the mountainous environment, and often require multiple methods to be used in combination. Ultimately, these measures only reduce the fluidity of the grout and cannot effectively prevent grout leakage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a pre-grouting method for preventing grout runoff in steeply inclined formations based on freezing, thereby solving the problems of existing technologies that cannot effectively guarantee the diffusion direction and distance of grout in steeply inclined formations, or that the grout can fully diffuse along a predetermined direction, but result in a large amount of ineffective space overflowing onto the ground or into the pre-grouted formation, increasing construction costs.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preventing grout leakage in pre-grouting of frozen, steeply dipping formations includes the following steps:

[0008] Step 1: In the area outside the pre-excavated shaft and its external grouting curtain target area, determine one or more turns of the freezing curtain line. The single or multiple turns of the freezing curtain line form the freezing curtain area.

[0009] Step 2: Install freezing holes along the freezing curtain line. The openings of the freezing holes are located on the surface freezing curtain line. The freezing holes are vertical or inclined in the direction of the stratum space. Multiple freezing holes form a group of freezing holes. The freezing holes on adjacent freezing curtain lines are arranged in parallel or staggered positions. The vertical depth of the freezing holes on multiple rings of freezing curtain lines increases from the inner ring to the outer ring.

[0010] Step 3: When implementing the pre-grouting curtain in the grouting curtain target area outside the wellbore, a freezing anti-grouting curtain is simultaneously implemented on the ground: water is injected into the freezing hole from the ground surface to a limited vertical depth of the formation, and then frozen after water injection to form a freezing anti-grouting curtain, preventing the grout from overflowing onto the ground along the formation dip angle so as to effectively fill and seal the fracture space of the injected formation.

[0011] Step 4: Arrange two inspection holes outside the above-mentioned group of freezing holes to check that the vertical depth of the drilled holes is not lower than the vertical depth of the outer ring of freezing holes. Check the effect of freezing and grout-preventing curtain by static observation or peep-in.

[0012] Step 5: After the pre-grouting curtain construction is completed, all freezing holes and inspection holes must be grouted and plugged.

[0013] The present invention also includes the following technical features:

[0014] Specifically, in step 1, the freezing curtain zone is determined based on the dip angle of the injected stratum, the spatial morphology, location, depth, and aquifer elevation of the target area of ​​the injected stratum, and to avoid interference with on-site structures caused by the freezing drilling machinery; the spacing between adjacent freezing curtain lines is 1m, and the distance from the freezing curtain line to the center of the pre-excavated wellbore is... D for:

[0015]

[0016] In the formula, —Distance from the grouting curtain target area to the center of the pre-excavated shaft, in meters;

[0017] —Structural dip angle, °;

[0018] —Pre-excavated shaft depth, m;

[0019] —Groundwater level, m.

[0020] Specifically, in step 2, the vertical depth of the freezing holes along the first ring of the freezing curtain line near the pre-excavated shaft side... for:

[0021]

[0022] In the formula, —Thermal conductivity of the injected formation, ;

[0023] —Average surface temperature of the injected formation ;

[0024] —Duration of freezing or thawing of the injected formation ;

[0025] —The melting of ice replaces heat ;

[0026] —Dry density of the injected formation ;

[0027] —Total water content of the soil and rock mass of the injected strata ;

[0028] —The unfrozen water content of the injected strata and soil ;

[0029] —The value range is 5~10m. The upper limit is taken when the degree of fracture development in the injected strata is high, and the lower limit is taken when the degree of fracture development in the injected strata is low.

[0030] The vertical depth of the freezing holes on the freezing curtain line adjacent to the first ring of the freezing curtain is 1.5. Furthermore, based on the number of frozen curtain lines, the number increases by 1.5 times from the inner circle to the outer circle.

[0031] Specifically, in step 2, the spacing between the freezing holes on the same ring of the freezing curtain line is 0.9 to 1.3 m.

[0032] Specifically, in step 2, if the drilling rig is affected by temporary structures or other factors on site when arranging the freezing holes, the distance to avoid the structures should not be less than 5m. At this time, the spacing between the freezing holes is increased, and the freezing holes with increased spacing are injected with pressurized water, while the other freezing holes are injected with static pressure water.

[0033] Specifically, in step 3, when performing ground pre-grouting in high-altitude and cold mountainous areas, water is directly injected into the freezing holes. The water in different freezing holes permeates and overlaps through the stratum fissures, forming a freezing and anti-grouting curtain by relying on the natural low-temperature environment of the high-altitude and cold mountainous areas, preventing the grout from overflowing onto the ground along the dip angle of the rock strata.

[0034] Specifically, in step 3, when performing ground pre-grouting in other non-high-altitude cold mountainous areas, water is injected into the freezing holes to ensure that the water content of the stratum in the freezing curtain section is greater than 10%. Artificial phase change refrigeration freezing is adopted, and the stratum water is frozen by using the sublimation of dry ice to absorb heat. A freezing anti-grouting curtain is formed in the stratum to prevent the grout from overflowing onto the ground along the stratum dip angle.

[0035] Specifically, natural low-temperature environments or artificial phase change refrigeration and freezing reduce the temperature of the pre-grouting formation. The following methods are used to prevent low temperatures from affecting the initial setting time and strength of the wellbore grout: heating the water used for pre-grouting production with an electric boiler by 5-10°C, increasing the content of triethanolamine and salt in the pre-grout, and adding water-reducing agents and increasing the cement content in the cement grout.

[0036] Specifically, in step 4, when grout overflows from the inspection hole, the grout flow direction and speed are changed by adjusting the grouting pressure, changing the grout flow rate, or increasing the freezing curtain range and freezing time, thereby controlling the grout overflow onto the ground.

[0037] Specifically, in step 5, multiple freezing holes on one or more freezing curtain lines can be frozen simultaneously, and the frozen bodies between each freezing hole overlap to form a frozen anti-slurry curtain.

[0038] Compared with the prior art, the present invention has the following technical effects:

[0039] (1) This invention adopts an active freezing anti-slurry curtain, which effectively controls the slurry diffusion distance and direction, unlike the existing anti-slurry distance and direction mechanisms. Most existing anti-slurry control technologies use methods such as changing slurry concentration, intermittent grouting, changing slurry type, and adding aggregates to the slurry. These methods require changing the slurry properties or grouting methods to reduce slurry fluidity. However, reducing slurry fluidity cannot completely guarantee that the slurry between adjacent grouting holes diffuses along the ideal direction and completely overlaps and fills the curtain target area, leaving gaps and weak points, thus reducing the curtain's impermeability. This invention adopts a borehole water injection freezing process. Based on the stratum dip angle and the spatial shape and location of the target area of ​​the injected stratum, freezing is carried out at a reasonable location in the injected stratum to form a frozen anti-slurry curtain body. This prevents the slurry from overflowing onto the ground or into the ineffective space of the stratum without changing the slurry fluidity, allowing the slurry to fully fill the stratum fissures in the target area. This is an active method of using a freezing curtain to prevent the slurry from overflowing onto the ground or into distant ineffective spaces along steeply dipped stratum fissures, thus improving the curtain grouting effect.

[0040] (2) This invention does not change the grout fluidity, grout properties, or grouting pressure, and can effectively control the grout diffusion direction and distance, reduce the amount of ineffective grout migration, and improve the impermeability of the curtain body: When the grout migrates through the formation fractures under the grouting pressure, it is in a free diffusion state and can diffuse far along the cavity of the dominant fracture channel, but the diffusion distance is limited in the inferior channel. Due to the complexity of the stratum being grouted and the artificial nature of curtain engineering, the design curtain line direction is often difficult to be consistent with the dominant channel of the stratum being grouted, especially in steeply dipped strata. If the grout fluidity, grout properties, or grouting pressure are changed, the grout may overflow the ground or diffuse into the ineffective space at a distance in the deep stratum, but may not be able to overlap with each other in the design curtain line direction to form a complete wall or cylinder, which cannot guarantee the grouting effect and causes a large amount of grout waste. Therefore, it is difficult to control grout loss by simply changing the grout fluidity, grout properties, or grouting pressure. This invention involves freezing the grout in a suitable location within the stratum by drilling and water injection, forming a frozen grout-preventing curtain. As the grout migrates through formation fractures under injection pressure, the frozen curtain effectively prevents it from spreading to the surface or unusable spaces within the stratum. The grout, hindered by the frozen curtain, actively seeks free space, changing its migration and diffusion direction until it fully fills the dominant fracture channels. Under stable injection pressure, the grout further fills the weaker fracture channels, ensuring the grouting effect and significantly improving the impermeability of the curtain wall.

[0041] (3) The present invention is simple in principle, low in cost, and easy to obtain materials. It can effectively prevent grout loss and improve the impermeability of the curtain: The present invention adopts the principle of active grout prevention by freezing the curtain. It does not require changing the grout properties, thus avoiding increased costs; it does not require changing the grouting pressure, thus avoiding reduced grout fluidity; it utilizes the formation water to freeze in the fissures at low temperatures to form a grout-stopping "ice cap", preventing the grout from flowing into ineffective spaces and blocking the grout in the target area of ​​the grouting curtain. This allows the grout to fully fill the dominant fissure channels in the target area and expand and seal the weaker fissure channels, thus effectively improving the impermeability of the curtain. Using this principle, in the implementation of the present invention, it is only necessary to construct freezing holes at a certain distance from the grouting holes and implement natural or artificial freezing to achieve the purpose of preventing grout from flowing into ineffective spaces. Compared with traditional grout control technologies such as changing grout concentration, intermittent grouting, changing grout type, and adding aggregate to the grout, the present invention is simple in principle, pollution-free, low in cost, easy to obtain materials, and has very strong practical effectiveness. Attached Figure Description

[0042] Figure 1 A schematic diagram showing the planar location of the pre-grouting and freezing hole group on the ground;

[0043] Figure 2 A schematic diagram showing the vertical positions of the pre-grouting and freezing hole group on the ground;

[0044] Figure 3 A schematic diagram showing the spatial location of the pre-grouting and freezing hole group on the ground.

[0045] Figure 4 A schematic diagram showing the spatial location of the pre-grouting and freezing hole group at the working face.

[0046] The meanings of the labels in the diagram are as follows:

[0047] 1-Pre-excavated well wall, 2-Grouting curtain target area, 3-Frozen hole group, 4-Frozen hole, 5-Inspection hole. Detailed Implementation

[0048] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0049] Example 1:

[0050] like Figures 1 to 4 As shown, this embodiment provides a method for preventing grout leakage through pre-grouting in frozen, steeply dipping formations, including the following steps:

[0051] Step 1: On the ground, around the pre-excavated shaft and the outer area of ​​the grouting curtain target zone, determine one or more freezing curtain lines. The single or multiple freezing curtain lines form the freezing curtain zone. The freezing grout-stopping curtain is implemented around the underground excavation working face. The freezing curtain zone and freezing curtain line are determined in combination with the stratum dip angle and the injection stratum target zone. The freezing curtain line can be arched, circular, closed, or open.

[0052] In step 1, the freezing curtain zone is determined based on the dip angle of the injected stratum, the spatial morphology, location, depth, and aquifer elevation of the target area of ​​the injected stratum, and to avoid interference with on-site structures caused by the freezing drilling machinery; the spacing between adjacent freezing curtain lines is 1m, and the distance from the freezing curtain line to the center of the pre-excavated wellbore is... D for:

[0053]

[0054] In the formula, —Distance from the grouting curtain target area to the center of the pre-excavated shaft, in meters;

[0055] —Structural dip angle, °;

[0056] —Pre-excavated shaft depth, m;

[0057] —Groundwater level, m.

[0058] Step 2: Based on the number and shape of the freezing curtain lines, freeze holes are laid out along the freezing curtain lines. The openings of the freeze holes are located on the surface freezing curtain lines. The freeze holes are vertical or inclined in the direction of the stratum space. The final position of the freeze holes is determined comprehensively based on the stratum dip angle, the location of the target area, and the seasonal frost depth of the site. Multiple freeze holes form a group of freeze holes. The freeze holes are single or multiple ring-shaped, straight, curved, or broken-line groups of holes, which are closed rings or open rings. When multiple or multiple rings of freeze holes are arranged, the freeze holes on adjacent freezing curtain lines are arranged in parallel alignment or parallel staggered arrangement on the plane. The vertical depth of the freeze holes on multiple rings of freezing curtain lines increases sequentially from the inner ring to the outer ring.

[0059] Freezing boreholes can be arranged parallel to the outline of the pre-built structure or inclined outward from the outline of the pre-built structure, starting from the working face and going deep into the strata. The final borehole depth is selected according to the length of the structure and the construction process design.

[0060] Based on factors such as the center of the wellbore, the location of on-site structures, and the dip angle of the formation, the freezing borehole group is arranged in a differentiated manner in the vertical space of the formation.

[0061] In step 2, the vertical depth of the freezing holes on the first ring of the freezing curtain line near the pre-excavated shaft side is determined. for:

[0062]

[0063] In the formula, —Thermal conductivity of the injected formation, ;

[0064] —Average surface temperature of the injected formation ;

[0065] —Duration of freezing or thawing of the injected formation ;

[0066] —The melting of ice replaces heat ;

[0067] —Dry density of the injected formation ;

[0068] —Total water content of the soil and rock mass of the injected strata ;

[0069] —The unfrozen water content of the injected strata and soil ;

[0070] —The value range is 5~10m. The upper limit is taken when the degree of fracture development in the injected strata is high, and the lower limit is taken when the degree of fracture development in the injected strata is low.

[0071] The vertical depth of the freezing holes on the freezing curtain line adjacent to the first ring of the freezing curtain is 1.5. Furthermore, based on the number of frozen curtain lines, the number increases by 1.5 times from the inner circle to the outer circle.

[0072] The spacing between freezing holes along the same ring of freezing curtain is 0.9–1.3 m.

[0073] When arranging freezing holes, if the drilling rig is affected by temporary structures in the well shaft or other factors on site, the distance from the structures should not be less than 5m. In this case, the spacing between freezing holes should be increased, and the freezing holes with increased spacing should be injected with pressurized water, while the other freezing holes should be injected with static pressure water.

[0074] Step 3: When implementing the pre-grouting and water-blocking curtain in the wellbore, a freezing anti-grouting curtain is simultaneously implemented on the ground: Water is injected from the surface to a limited vertical depth into the freezing hole outside the target area of ​​the injected formation. After water injection, it freezes, forming a frozen grout-stopping plate wall or a frozen grout-stopping barrel wall, i.e., a freezing anti-grouting curtain. This prevents the grout from overflowing onto the ground along the dip angle of the formation, effectively controlling the grout migration distance and direction, so that the grout can effectively fill and seal the fracture space of the injected formation inside the grout-stopping plate wall or grout-stopping barrel wall.

[0075] When implementing a ground-freezing anti-grouting curtain, water is directly injected into the freezing holes during ground pre-grouting in high-altitude and cold mountainous areas. Water from different freezing holes seeps through and overlaps through geological fissures, relying on the natural low-temperature environment of high-altitude and cold mountainous areas to form a ground-freezing anti-grouting curtain, preventing grout from overflowing onto the ground along the dip angle of the rock strata.

[0076] When performing ground pre-grouting in other non-high-altitude and cold mountainous areas, water is injected into the freezing holes to ensure that the water content of the stratum in the freezing curtain section is greater than 10%. Artificial phase change refrigeration freezing is adopted, and the sublimation of dry ice absorbs heat to freeze the stratum water, forming a freezing curtain to prevent grout from overflowing onto the ground along the stratum dip angle.

[0077] When the freezing anti-slurry technology is applied to effectively control the diffusion distance and direction of slurry, the natural low temperature environment or artificial phase change refrigeration and freezing reduces the temperature of the pre-grouting formation. The following methods are used to prevent the low temperature from affecting the initial setting time and strength of the wellbore grout: heating the water used for pre-grouting production with an electric boiler by 5~10℃, increasing the content of triethanolamine and salt in the pre-grouting, and adding water-reducing agent and increasing the cement content in the cement slurry.

[0078] Step 4: Arrange two inspection holes outside the above-mentioned group of freezing holes to check that the vertical depth of the drilled holes is not lower than the vertical depth of the outer ring of freezing holes. Check the effect of freezing and grout-preventing curtain by static observation or internal inspection.

[0079] When grout overflows from the inspection hole, the grout flow direction and speed can be changed by adjusting the grouting pressure, changing the grout flow rate, or increasing the freezing curtain range and freezing time, so as to control the grout overflow from the ground and prevent ineffective grouting.

[0080] Step 5: The above-mentioned freezing hole group is frozen simultaneously. After the pre-grouting curtain construction is completed, all freezing holes and inspection holes must be grouted and plugged. Multiple freezing holes on a single or multiple freezing curtain line can be frozen simultaneously, and the frozen bodies between each freezing hole overlap to form a freezing curtain to prevent grout leakage.

Claims

1. A frozen-based large-dip-angle stratum advance pre-grouting anti-slurry-running method, characterized in that, Includes the following steps: Step 1: In the area outside the pre-excavated shaft and its external grouting curtain target area, determine one or more turns of the freezing curtain line. The single or multiple turns of the freezing curtain line form the freezing curtain area. Step 2: Install freezing holes along the freezing curtain line. The openings of the freezing holes are located on the surface freezing curtain line. The freezing holes are vertical or inclined in the direction of the stratum space. Multiple freezing holes form a group of freezing holes. The freezing holes on adjacent freezing curtain lines are arranged in parallel or staggered positions. The vertical depth of the freezing holes on multiple rings of freezing curtain lines increases from the inner ring to the outer ring. Step 3: When implementing the pre-grouting curtain in the grouting curtain target area outside the wellbore, a freezing anti-grouting curtain is simultaneously implemented on the ground: water is injected into the freezing hole from the ground surface to a limited vertical depth of the formation, and then frozen after water injection to form a freezing anti-grouting curtain, preventing the grout from overflowing onto the ground along the formation dip angle so as to effectively fill and seal the fracture space of the injected formation. Step 4: Arrange two inspection holes outside the above-mentioned group of freezing holes to check that the vertical depth of the drilled holes is not lower than the vertical depth of the outer ring of freezing holes. Check the effect of freezing and grout-preventing curtain by static observation or peep-in. Step 5: After the pre-grouting curtain construction is completed, all freezing holes and inspection holes must be grouted and plugged. In step 1, the freezing curtain zone is determined based on the dip angle of the injected stratum, the spatial morphology, location, depth, and aquifer elevation of the target area of ​​the injected stratum, while avoiding interference with on-site structures caused by the drilling machinery for the freezing holes; the spacing between adjacent freezing curtain lines is 1m, and the distance from the freezing curtain line to the center of the pre-excavated wellbore is... D for: In the formula, —Distance from the grouting curtain target area to the center of the pre-excavated shaft, in meters; —Structural dip angle, °; —Pre-excavated shaft depth, m; —Groundwater level, in meters; In step 2, the vertical depth of the freezing holes on the first ring of the freezing curtain line near the pre-excavated shaft side is determined. for: In the formula, —Thermal conductivity of the injected formation, ; —Average surface temperature of the injected formation ; —Duration of freezing or thawing of the injected formation ; —The melting of ice replaces heat ; —Dry density of the injected formation ; —Total water content of the soil and rock mass of the injected strata ; —The content of unfrozen water in the injected strata and soil. ; —The value range is 5~10m. The upper limit is taken when the degree of fracture development in the injected strata is high, and the lower limit is taken when the degree of fracture development in the injected strata is low. The vertical depth of the freezing holes on the freezing curtain line adjacent to the first ring of the freezing curtain is 1.

5. Furthermore, based on the number of frozen curtain lines, the number increases by 1.5 times from the inner circle to the outer circle. In step 3, when performing ground pre-grouting in high-altitude and cold mountainous areas, water is directly injected into the freezing holes. The water in different freezing holes permeates and overlaps through the stratum fissures, forming a freezing anti-grouting curtain by relying on the natural low temperature environment of the high-altitude and cold mountainous areas, preventing the grout from overflowing onto the ground along the stratum dip angle. In step 3, when performing ground pre-grouting in other non-high-altitude cold mountainous areas, water is injected into the freezing holes to ensure that the water content of the stratum in the freezing curtain section is greater than 10%. Artificial phase change refrigeration freezing is adopted, and the sublimation of dry ice absorbs heat to freeze the stratum water, forming a freezing curtain to prevent grout from overflowing onto the ground along the stratum dip angle.

2. The method for preventing grout leakage based on pre-grouting in frozen, steeply dipping formations as described in claim 1, characterized in that, In step 2, the spacing between the freezing holes on the same ring of the freezing curtain line is 0.9 to 1.3 m.

3. The method for preventing grout leakage based on pre-grouting in frozen, steeply dipping formations as described in claim 1, characterized in that, In step 2, if the drilling rig operation is affected by nearby structures or other factors on site when arranging the freezing holes, the distance to avoid the structures should not be less than 5m. At this time, the spacing between the freezing holes is increased, and the freezing holes with increased spacing are injected with pressurized water, while the other freezing holes are injected with static pressure water.

4. The method for preventing grout leakage based on pre-grouting in frozen, steeply dipping formations as described in claim 1, characterized in that, Natural low-temperature environments or artificial phase change refrigeration and freezing reduce the temperature of the pre-grouting formation. The following methods are used to prevent low temperatures from affecting the initial setting time and strength of the wellbore grout: heating the water used for pre-grouting production with an electric boiler by 5-10°C, increasing the content of triethanolamine and salt in the pre-grout, and adding water-reducing agents and increasing the cement content in the cement grout.

5. The method for preventing grout leakage based on pre-grouting in frozen, steeply dipping formations as described in claim 1, characterized in that, In step 4, when grout overflows from the inspection hole, the grout flow direction and speed are changed by adjusting the grouting pressure, changing the grout flow rate, or increasing the freezing curtain range and freezing time, thereby controlling the grout overflow onto the ground.

6. The method for preventing grout leakage based on pre-grouting in frozen, steeply dipping formations as described in claim 1, characterized in that, In step 5, multiple freezing holes on a single or multiple-loop freezing curtain line can be frozen simultaneously, and the frozen bodies between each freezing hole overlap to form a frozen anti-slurry curtain.

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