CN110700842A - An advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end - Google Patents

Abstract

The invention discloses an advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end, which solves the problem that the cement slurry in the prior art is difficult to effectively retain in the water-rich sand layer, and the slurry is easy to exist in the grouting process. Problems such as the upper back and running of the slurry can effectively strengthen the water-rich sand layer at the end of the shield. The technical scheme includes the following steps: determining the target reinforcement area and designing grouting holes; arranging surface deformation monitoring points and station structure displacement monitoring points; making orifice pipes with geotextile bags; The orifice pipe is placed in the grouting hole; the geotextile bag is grouted, the surrounding stratum is compacted, and the grouting rock plate is constructed; the fast-setting grouting material is used to carry out forward segment grouting in the target reinforcement area, and the grouting process Real-time monitoring of surface deformation and displacement of station structure; feedback adjustment of grouting design through monitoring data of surface deformation and displacement of station structure; completion of grouting work for all grouting holes and inspection of grouting effect.

Description

An advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end

technical field

The invention relates to the field of tunnels and underground engineering, in particular to an advanced grouting reinforcement method suitable for a water-rich sand layer section at the end of a shield.

Background technique

When the shield starts or receives tunneling at the shield end area, the stress state of the stratum changes abruptly, and the stability of the stratum is poor, especially when the shield end area is located in the water-rich sand layer, due to the water-rich sand layer. It has the characteristics of loose structure, strong water richness and poor self-stabilizing ability, which is very prone to sand collapse and landslide accidents, resulting in the inability of shield tunneling.

The existing reinforcement methods for shield ends mainly include rotary jetting method, precipitation method and sleeve valve grouting method, etc. The rotary jetting method mainly uses high-pressure jet technology to forcibly cut, stir and mix the stratum and cement slurry to form a rotary jetted pile body. , and then form continuous reinforcement through the occlusion between different jetting piles, and finally achieve the purpose of stratum reinforcement and water-stopping. The inventor found that in the process of rotary jetting construction of the water-rich sand layer, it is difficult for the cement slurry to be effectively retained in the water-rich sand layer, resulting in poor pile forming effect, low occlusion of the rotary jet pile, and difficulty in stratum reinforcement effect meeting the shield end. reinforcement requirements.

The precipitation method is mainly to pump water to the target stratum to reduce the water content of the stratum and improve the stratum performance. However, since precipitation will cause the subsidence of the surrounding strata, it is difficult to apply in the urban environment where buildings and municipal pipelines are densely distributed. The sleeve valve grouting method achieves the purpose of impermeability and reinforcement by implementing the backward grouting from the deep part of the stratum to the shallow part of the stratum. However, the application of this method in water-rich sand layers has three disadvantages. First, due to the weak grouting measures of the sleeve valve pipe grouting method, the grouting process is prone to the problem of back-running of the grouting, which leads to the problem of grouting in the target reinforcement area. The retention rate of the slurry and the grouting pressure are low, and the reinforcement effect is difficult to guarantee; the second is that the slurry is easy to spread in the shallow part of the formation, causing the surface to rise significantly. If there is a municipal pipeline on the surface, it will seriously threaten the safety of the municipal pipeline; the third is the water-rich sand layer Difficulty in drilling and serious hole collapse in the drilled hole make it difficult to install the sleeve valve tube in place and the construction efficiency is low.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention provides an advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end, which has the effect of effectively reinforcing the water-rich sand layer at the shield end.

The present invention adopts following technical scheme:

An advanced grouting reinforcement method suitable for a water-rich sand layer at a shield end, comprising the following steps:

Step 1: Determine the target reinforcement area and design grouting holes;

Step 2: Arrange surface deformation monitoring points and station structure displacement monitoring points;

Step 3: Make an orifice tube with an expandable geotextile bag;

Step 4: Set up a grouting hole and lower the orifice pipe in the grouting hole;

Step 5: Carry out grouting to the geotextile bag located in the grouting hole, compact the surrounding stratum, and construct a grouting rock plate;

Step 6: Use rapid-setting grouting material to implement forward segmented grouting to the target reinforcement area, and monitor the surface deformation and the displacement of the station structure in real time during the grouting process;

Step 7: Feedback and adjust the grouting design through the monitoring data of the surface deformation and the displacement of the station structure;

Step 8: Complete the grouting work of all grouting holes, and check the grouting effect.

Further, in the step 1, the plane range of the target reinforcement area is expanded by 3-4m from the shield tunnel outline in the direction perpendicular to the shield tunnel axis, and the station enclosure structure in the direction parallel to the shield tunnel axis. The boundary is shifted by 6-8m; the vertical range of the target reinforcement area is 3-4m above the line of the shield tunnel vault, and 1-1.5m below the height of the shield tunnel's bottom.

Further, in the second step, the arrangement range of the surface deformation monitoring points is the set distance of the expansion of the plane range of the target reinforcement area, and the distance between the adjacent surface deformation monitoring points is 3-5m;

The displacement monitoring points of the station structure are arranged on the station envelope. The distance between the displacement monitoring points of the adjacent station structures is 3-5m, and the displacement monitoring direction is the horizontal direction.

Further, a flange plate is installed on the top of the orifice pipe, and a grouting valve is arranged above the flange plate; the end of the orifice pipe is flush with the upper boundary of the target reinforcement area.

Further, the geotextile bag is fixed on the outer side of the orifice pipe, a grouting pipe is arranged on one side of the orifice pipe, and the end of the grouting pipe extends into the interior of the geotextile bag.

Further, in the fifth step, the geotextile bag is grouted with a quick-setting type slurry through a grouting pipe, and the gel time of the quick-setting type slurry is less than 20s.

Further, in the step 6, the quick-setting grouting material adopts cement-water glass double-liquid slurry, the water-cement mass ratio of the cement slurry is controlled between W/C=0.8-1, and the double-liquid cement slurry and water glass slurry are used. The volume ratio is controlled between C:S=3～4:1.

Further, in the sixth step, when the grouting pressure reaches the design grouting final pressure and the grouting amount reaches 80% of the design grouting amount, the grouting is stopped, and when the grouting amount reaches 1.5 times the design grouting amount, the grouting is stopped. Stop grouting when the pressure does not reach the design final grouting pressure, and stop grouting when the grouting pressure does not reach the design final grouting pressure and the grouting amount does not reach the design grouting amount, but the surface deformation or the displacement of the station structure exceeds the warning value.

Further, in the seventh step, when the maximum surface uplift deformation caused by a single grouting exceeds 0.3 cm or the displacement of the station structure exceeds 0.2 cm, the design grouting amount is reduced.

Further, in the eighth step, the inspection of the grouting effect includes a water pressure test, a drilling core and a drilling video inspection.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention uses the expandable geotextile bag to apply a squeezing force to the stratum above the target reinforcement area, and the stratum around the geotextile bag is compacted to form a stratum compaction area, and the ability of the stratum to resist the splitting damage of the slurry is improved. The lap joint of the grouting area forms a stop rock disk above the target reinforcement area to prevent the slurry from returning during the grouting process;

(2) The present invention adopts the fast-setting slurry, and uses its fast-gel properties to effectively limit the diffusion range of the slurry, and finally greatly improves the slurry retention rate in the target reinforcement area, so that the grouting reinforcement effect is greatly improved, and it meets the requirements of shield tunneling. And accept the requirements for the mechanical properties of the shield end formation;

(3) Compared with the rotary jet method and the sleeve valve pipe grouting method, the present invention can achieve a better reinforcement effect of the water-rich sand layer, effectively ensuring the construction safety of the shield starting and receiving process; compared with the sleeve valve pipe grouting The method can prevent the slurry from spreading in the shallow part of the stratum and avoid the surface uplift value exceeding the limit; compared with the rotary spray method, this method has simple equipment, high construction efficiency, shortens the entire operation time and lower cost.

Description of drawings

The accompanying drawings that form a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute improper limitations on the present application.

Fig. 1 is the plan view of the target reinforcement area of the water-rich sand section of the shield tunnel according to the first embodiment of the present invention;

Fig. 2 is the longitudinal sectional view of the target reinforcement area of the water-rich sand section of the shield tunnel according to the first embodiment of the present invention;

3 is a cross-sectional view of the target reinforcement area of the water-rich sand section of the shield tunnel according to Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram of the construction of the igneous stop rock plate and the progressive grouting according to the first embodiment of the present invention;

Among them, 1. Shield tunnel, 2. Water-rich sand layer, 3. Target reinforcement area, 4. Grouting drilling, 5. Station envelope structure, 6. Surface deformation monitoring point, 7. Station structure displacement monitoring point, 8. Layout range of surface deformation monitoring points; 9. Surface, 10, Geotextile bag, 11, Orifice pipe, 12, Flange plate, 13, Grouting valve, 14, Grouting pipe, 15, Stopping rock plate, 16 , stratum compaction area, 17, the first grouting section, 18, the second grouting section, 19, the third grouting section.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that the presence of features, steps, operations, devices, components and/or combinations thereof;

For the convenience of description, if the words "up", "down", "left" and "right" appear in this application, it only means that the directions of up, down, left and right are consistent with the drawings themselves, and do not limit the structure. It is to facilitate the description of the present invention and to simplify the description, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as a limitation on the application.

Terminology explanation part: Terms such as "installation", "connection", "connection", "fixation" in this application should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated; It can be a mechanical connection, it can also be an electrical connection, it can be a direct connection, it can also be indirectly connected through an intermediate medium, it can be an internal connection between two elements, or an interaction relationship between two elements, for those of ordinary skill in the art. , the specific meanings of the above terms in the present invention can be understood according to specific situations.

As described in the background art, in the prior art, it is difficult for the cement slurry to be effectively retained in the water-rich sand layer, and the slurry tends to run back and forth during the grouting process. In order to solve the above technical problems, the present invention proposes a An advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end.

Example 1:

The present invention will be described in detail below in conjunction with accompanying drawings 1-4. Specifically, the structure is as follows:

This embodiment provides an advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end, which can effectively reinforce the water-rich sand layer 2 at the shield end, including the following steps:

Step 1: Determine the target reinforcement area 3 and design the grouting hole 4;

In order to ensure the excavation stability of the tunnel, the scope of the target reinforcement area should be larger than a certain limit, and considering the engineering economy, the scope of the target reinforcement area should not be too large. Therefore, the plane range of the target reinforcement area 3 is perpendicular to the shield. In the axial direction of the shield tunnel 1, the outline of the shield tunnel 1 is expanded by 3 to 4 m, and in the direction parallel to the axial direction of the shield tunnel 1, the boundary of the station enclosure structure 5 is translated by 6 to 8 m.

In the process of tunnel excavation, the excavation safety risk at the top of the vault is greater than that at the bottom of the vault, so the vertical range of the target reinforcement area is moved from the height of the shield tunnel vault to the line longer than that of the shield tunnel. The length by which the base height line moves down. In this embodiment, the vertical range of the target reinforcement area 3 is that the height of the vault of the shield tunnel 1 is moved 3 to 4 m above the line, and the height of the bottom of the shield of the shield tunnel 1 is moved down by 1 to 1.5 m. The grouting boreholes 4 are arranged in a plum blossom shape, and the spacing between adjacent grouting boreholes 4 is generally 1.5-2.5m.

Step 2: Arrange surface deformation monitoring points 6 and station structure displacement monitoring points 7;

Because the surface deformation and station structure displacement caused by the grouting process are not uniform in the surface area, the layout of the surface deformation monitoring points and the station structure displacement monitoring points should meet certain density requirements to meet the monitoring accuracy requirements. As shown in Figure 1, the layout range 8 of the surface deformation monitoring points is the expansion of the plane range of the target reinforcement area 3 by 3m, and the distance between the adjacent surface deformation monitoring points 6 is 3-5m; the station structure displacement monitoring point 7 is arranged in the station enclosure On the structure 5, the distance between the structural displacement monitoring points 7 of adjacent stations is 3 to 5 m, and the displacement monitoring direction is the horizontal direction.

Step 3: making the orifice pipe 11 with the expandable geotextile bag 10;

A flange 12 is mounted on the top of the orifice pipe 11 . In this embodiment, the flange 12 is fixed to the orifice pipe 11 by welding. The diameter of the orifice pipe 11 can be selected according to the actual situation. The orifice pipe 11 in this embodiment adopts a steel sleeve with a diameter of 108 mm. A grouting valve 13 is installed above the flange 12 .

The geotextile bag 10 is fixed on the outside of the orifice pipe 11, and a grouting pipe 14 is welded on one side of the orifice pipe 11. The location near Lanpan 12. The grouting pipe 14 is a steel pipe, and the geotextile bag 10 is made of high-strength geotextile. The length of the geotextile bag is 1.5-2.5m, and the circumference is 1-1.3m.

Step 4: Drill a grouting hole 4 below the ground surface 9 and lower the orifice pipe 11 in the grouting hole 4 so that the end of the orifice pipe 11 is flush with the upper boundary of the target reinforcement area 3 .

Step 5: Perform grouting on the geotextile bag 10 located in the grouting hole 4 , compact the surrounding stratum, and construct a grouting rock pan 15 .

Further, the geotextile bag 10 is grouted with quick-setting slurries through the grouting pipe 14, the grouting pressure is 2-3 MPa, the gel time of the quick-setting slurries is less than 20s, and the volume of the slurries is stable and does not shrink after gelation. The purpose of grouting the geotextile bag with quick-setting slurries is to reduce the amount of water segregation of the grout stone in the civil cloth bag. The use of quick-setting slurry will effectively shorten the gel time of the slurry, reduce the amount of water separation of the slurry, keep the volume of the slurry stone body stable, and maintain the extrusion stress of the geotextile bag on the surrounding strata.

The expansive action of the geotextile bag 10 exerts a squeezing force on the surrounding stratum, and the surrounding stratum is compacted to form a stratum compaction zone 16. After the stratum is compacted, its strength is much higher than that of the original stratum, and the ability to resist slurry splitting damage is significantly enhanced. When a plurality of geotextile bags 10 are expanded, the compacted areas of adjacent strata overlap each other, and a stop rock 15 will be formed above the target reinforcement area 3, which prevents the slurry from returning up, and restricts the diffusion range of the slurry at the target reinforcement area. In the area 3, the slurry retention rate in the target reinforcement area 3 is greatly improved.

Step 6: Use rapid-setting grouting material to implement forward segmented grouting in the target reinforcement area 3, and monitor the surface deformation and the displacement of the station structure in real time during the grouting process; the real-time monitoring of the surface deformation is to prevent surface deformation and municipal pipeline deformation. The purpose of real-time monitoring of the displacement of the station structure beyond the allowable value of the specification is to ensure that the adverse effect of grouting on the station structure is controlled within the allowable value of the specification.

The purpose of using the quick-setting grouting material is to use its rapid solidification characteristics to limit the diffusion range of the slurry, keep the slurry as much as possible in the target reinforcement area, and improve the grouting reinforcement effect. The quick-setting grouting material adopts cement-water glass double-liquid slurry, the water-cement mass ratio of cement slurry is controlled between W/C=0.8~1, and the double-liquid volume ratio of cement slurry and water glass slurry is controlled at C:S=3 ~4:1.

The grouting end standard of single grouting adopts the three-control grouting end standard of "quantity, pressure and deformation". When the grouting pressure reaches the design grouting final pressure and the grouting amount reaches 80% of the design grouting amount, the grouting is stopped. ; Stop grouting when the grouting amount reaches 1.5 times the design grouting amount and the grouting pressure does not reach the design grouting final pressure; when the grouting pressure does not reach the design grouting final pressure and the grouting amount does not reach the design grouting amount , but stop grouting when the surface deformation or the displacement of the station structure exceeds the warning value. Design grouting final pressure can be 1-1.5MPa, design grouting volume can be 1.5-2.5m ³ , surface deformation or station structure displacement early warning value is determined according to actual engineering requirements and local code requirements.

The grouting sequence of the grouting hole 4 is the outer ring and then the inner ring, and the outer ring is grouted first to form a surrounding structure, which limits the range of slurry diffusion for subsequent grouting and improves the retention rate of the slurry in the target reinforcement area.

The segmental length of advance segmented grouting is 3-4m. Through advance type grouting, the shallow strata in the 3 areas of the target reinforcement area are first reinforced, and then the grouting depth is gradually increased from shallow to deep until the target reinforcement area is reached. 3 bottom borders. As shown in FIG. 4 , the first grouting section 17 is reinforced first, and then the second grouting section 18 and the third grouting section 19 are reinforced in sequence. Since the shallow water-rich sand layer has been reinforced in the previous grouting, the subsequent grouting construction can avoid the problems of difficult drilling and serious hole collapse in the water-rich sand layer.

Step 7: Feedback and adjust the grouting design through the monitoring data of the surface deformation and the displacement of the station structure. The total limit of the surface uplift and the total displacement of the station structure caused by the whole grouting process are selected according to the specifications. The total limit of uplift and the total limit of station structure displacement. When the maximum surface uplift deformation caused by a single grouting exceeds 0.3 cm or the displacement of the station structure exceeds 0.2 cm, the design grouting amount should be appropriately reduced.

Step 8: Complete the grouting work of all grouting holes, and check the grouting effect. The grouting effect inspection includes water pressure test, borehole coring and borehole video exploration. When the reinforced formation permeability coefficient obtained by the water pressure test is <1×10 ^-6 cm/s, the borehole coring rate is >50%, the drilling When there is no collapsed hole in the hole TV inspection inspection hole, it is considered that the grouting effect meets the requirements.

Embodiment 2:

In this example, an interval tunnel of a subway project is taken as an example. The shield tunnel method is used for excavation. The vault depth of shield tunnel 1 is 10m, the excavation diameter of shield tunnel 1 is 6.5m, and the clear distance of two shield tunnels 1 is 8m. , At the end of the shield, the full section of the shield tunnel 1 passes through the water-rich sand layer 2, and the construction risk is extremely high.

Use the following steps to reinforce:

Step 1: Determine the target reinforcement area 3 and design the surface grouting hole 4. The plane range of the target reinforcement area 3 is extended by 4m from the outline of the shield tunnel 1 in the direction perpendicular to the axis of the tunnel, and is translated by 8m from the boundary of the station envelope 5 in the direction parallel to the axis of the shield tunnel 1. The vertical range is that the height of the vault of shield tunnel 1 is moved 4m above the line, and the height of the bottom of the shield of shield tunnel 1 is moved down by 1m. The ground grouting boreholes 4 are arranged in a plum-shaped arrangement, and the hole spacing is designed to be 2m.

Step 2: Arrange surface deformation monitoring points 6 and station structure displacement monitoring points 7. The layout range 8 of the surface deformation monitoring points is to expand the plane range of the target reinforcement area 3 by 3m, and the distance between the surface deformation monitoring points 6 is 5m. The station structure displacement monitoring points 7 are arranged on the station enclosure structure 5, the distance between the station structure displacement monitoring points 7 is 5m, and the displacement monitoring direction is the horizontal direction.

Step 3: Making the orifice pipe 11 with the geotextile bag 10 , welding the grouting pipe 14 on the side of the orifice pipe 11 , and the end of the grouting pipe 14 extending into the interior of the geotextile bag 10 . The orifice pipe 11 adopts a steel casing with a diameter of 108 mm, and a flange 12 is welded on the upper part of the orifice pipe 11 , and the flange 12 is connected to the grouting valve 13 . The geotextile bag 10 is made of high-strength geotextile. Both ends of the geotextile bag 10 are tied and fixed on the orifice pipe 11, and one end of the geotextile bag 10 is tied to the end (end) of the orifice pipe 11. The length of the geotextile bag 10 is 2m. 10 The perimeter after expansion is 1.2m.

Step 4: Drill the grouting hole 4 and lower the orifice pipe 11. The depth of the orifice tube 11 is directly to the upper boundary of the target reinforcement area 3 .

Step 5: Perform grouting on the geotextile bags 10 of all the grouting holes 4 , compact the surrounding strata, and construct a grouting rock pan 15 . The geotextile bags 10 of all the grouting holes 4 are grouted with the quick-setting slurries through the grouting pipes 14, and the grouting pressure is 2-3 MPa. The quick-setting slurries require a gel time of <20s. The quick-setting slurry in this embodiment adopts cement-sodium silicate slurry, the cement slurry water-cement mass ratio is W/C=1, and the double-liquid volume ratio of cement slurry and water glass slurry is C:S=4:1.

The expansive action of the geotextile bag 10 exerts a squeezing force on the surrounding stratum, and the surrounding stratum is compacted to form a stratum compaction zone 16. After the stratum is compacted, its strength is much higher than that of the original stratum, and the ability to resist slurry splitting damage is significantly enhanced. When a plurality of geotextile bags 10 are expanded, the compaction areas 16 of adjacent strata overlap each other, and a stop rock disk 15 will be formed above the target reinforcement area 3, which prevents the slurry from returning up and restricts the slurry diffusion range. In the reinforcement area 3, the slurry retention rate in the target reinforcement area 3 is greatly improved.

Step 6: Use the fast-setting grouting material to implement forward segmented grouting to the target reinforcement area 3, and monitor the surface deformation and the displacement of the station structure in real time during the grouting process.

The materials used for grouting are quick-setting grouting materials, and cement-water glass double-liquid slurry can be used. = 4:1. During the grouting process, the surface deformation and the displacement of the station structure are monitored in real time to prevent the surface deformation and the deformation of the municipal pipeline from exceeding the allowable value of the specification, and at the same time to ensure that the adverse effect of grouting on the station structure is controlled within the allowable value of the specification.

The grouting end standard of single grouting adopts the three-control grouting end standard of "quantity, pressure and deformation". When the grouting pressure reaches the design grouting final pressure and the grouting amount reaches 80% of the design grouting amount, the grouting is stopped. ; Stop grouting when the grouting amount reaches 1.5 times the design grouting amount and the grouting pressure does not reach the design grouting final pressure; when the grouting pressure does not reach the design grouting final pressure and the grouting amount does not reach the design grouting amount , but stop grouting when the surface deformation or the displacement of the station structure exceeds the warning value. The design final pressure of grouting is 1.2MPa, and the design grouting amount is 2.5m ³ . The early warning value of surface deformation or station structure displacement is determined according to actual engineering requirements and local code requirements. The early warning value of structural displacement is 0.5cm, and the segmental length of forward segmented grouting is 4m.

Step 7: Feedback and adjust the grouting design based on the surface deformation monitoring data and the station structure displacement monitoring data. When the maximum surface uplift deformation caused by a single grouting exceeds 0.3 cm, or the resulting displacement of the station structure exceeds 0.2 cm, the design grouting amount should be appropriately reduced.

Step 8: Complete the grouting work of all grouting holes, and check the grouting effect. When the reinforced formation permeability coefficient obtained from the pressurized water test is less than 1×10 ^-6 cm/s, the drilling core rate is more than 50%, and there is no collapsed hole in the borehole TV inspection inspection hole, the grouting effect is considered to meet the requirements. In this embodiment, the average permeability coefficient of the stratum after grouting reinforcement is 5.2×10 ^-7 cm/s, the core rate of the inspection hole is generally above 65%, and the inspection hole basically does not have hole collapse phenomenon, and the grouting effect meet the target requirements.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (10)

1. a kind of advance grouting reinforcement method that is applicable to the water-rich sand section of shield end, is characterized in that, comprises the following steps: Step 1: Determine the target reinforcement area and design grouting holes; Step 2: Arrange surface deformation monitoring points and station structure displacement monitoring points; Step 3: Make an orifice tube with an expandable geotextile bag; Step 4: Set up a grouting hole and lower the orifice pipe in the grouting hole; Step 5: Carry out grouting to the geotextile bag located in the grouting hole, compact the surrounding stratum, and construct a grouting rock plate; Step 6: Use rapid-setting grouting material to implement forward segmented grouting to the target reinforcement area, and monitor the surface deformation and the displacement of the station structure in real time during the grouting process; Step 7: Feedback and adjust the grouting design through the monitoring data of the surface deformation and the displacement of the station structure; Step 8: Complete the grouting work of all grouting holes, and check the grouting effect. 2. A kind of advance grouting reinforcement method suitable for the water-rich sand section at the shield end according to claim 1, characterized in that, in the step 1, the plane range of the target reinforcement area is perpendicular to the shield. In the direction of the tunnel axis, the outline of the shield tunnel is expanded by 3-4m, and the boundary of the station enclosure is translated by 6-8m in the direction parallel to the axis of the shield tunnel; the vertical range of the target reinforcement area is the height of the shield tunnel vault The line is moved 3 to 4m, and the height of the shield tunnel arch bottom is moved down by 1 to 1.5m. 3. A kind of advance grouting reinforcement method suitable for the water-rich sand layer at the shield end according to claim 1, characterized in that, in the second step, the surface deformation monitoring point arrangement range is within the target reinforcement area. Expand the set distance outside the plane range, and the distance between adjacent surface deformation monitoring points is 3-5m; The displacement monitoring points of the station structure are arranged on the station envelope. The distance between the displacement monitoring points of the adjacent station structures is 3-5m, and the displacement monitoring direction is the horizontal direction. 4. A kind of advance grouting reinforcement method suitable for the water-rich sand layer at the shield end according to claim 1, characterized in that, a flange is installed on the top of the orifice pipe, and the flange is There is a grouting valve above; the end of the orifice tube is flush with the upper boundary of the target reinforcement area. The advanced grouting reinforcement method suitable for the water-rich sand section at the shield end according to claim 1, wherein the geotextile bag is fixed on the outer side of the orifice pipe, and one side of the orifice pipe is A grouting pipe is provided, and the end of the grouting pipe extends into the interior of the geotextile bag. 6 . A method for advanced grouting reinforcement suitable for the water-rich sand layer at the shield end according to claim 1 , wherein in the step 5, a quick-setting type slurry is used to compress the geotechnical engineering through a grouting pipe. 7 . The cloth bag is used for grouting, and the gel time of the quick-setting slurry is less than 20s. 7 . The method of advance grouting and reinforcement suitable for the water-rich sand section at the shield end according to claim 1 , wherein in the step 6, the quick-setting grouting material adopts a cement-water glass double grouting material. 8 . Slurry, the water-cement mass ratio of cement slurry is controlled between W/C=0.8-1, and the double-liquid volume ratio of cement slurry and water glass slurry is controlled between C:S=3-4:1. 8 . The advanced grouting reinforcement method suitable for the water-rich sand layer at the shield end according to claim 1 , wherein in the step 6, when the grouting pressure reaches the design grouting final pressure and Stop grouting when the grouting amount reaches 80% of the design grouting amount, stop grouting when the grouting amount reaches 1.5 times the design grouting amount but the grouting pressure does not reach the design final grouting pressure, and stop when the grouting pressure does not reach the design grouting final pressure The final grouting pressure and grouting amount do not reach the design grouting amount, but the grouting is stopped when the surface deformation or the displacement of the station structure exceeds the warning value. 9 . The method of advance grouting for strengthening the water-rich sand layer at the shield end according to claim 1 , wherein in the seventh step, when the maximum surface uplift deformation caused by a single grouting When the amount exceeds 0.3cm or the displacement of the station structure exceeds 0.2cm, reduce the design grouting amount. 10 . A method for advanced grouting reinforcement suitable for water-rich sand layers at shield ends according to claim 1 , wherein in the eighth step, the grouting effect inspection includes a water pressure test, drilling Coring and drilling TV exploration.

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