In-situ test method based on shield docking curtain grouting

Abstract

Disclosed in the present invention is an in-situ test method based on shield docking curtain grouting. By designing the number of loops and length of curtain grouting pipes, complete interconnection of grout ejected from each pipe is achieved, and by using the minimum number of curtain grouting pipes, the grouting reinforcement range of a surrounding rock satisfies design requirements, and water channels in the surrounding rock are fully filled, thereby providing a stable water-free environment for subsequent excavation, and effectively solving the problems in the prior art that, for example, the reinforcement range of the surrounding rock in a shield docking section is affected due to being lack of a theoretical calculation basis, an excessively large spacing between the pipes leads to poor interconnection quality of grout, and the reinforcement and water-sealing effects on the surrounding rock in the docking section are significantly affected. Moreover, by drilling holes and providing sensors in the holes in advance within the grouting range, the present invention monitors, in real time, stratum pressure response caused by grout pressure during grouting and a stratum temperature change caused by hydration heat of grout, thereby providing data support for the selection of grouting parameters in stratum grouting reinforcement engineering.

Description

An in-situ test method based on shield tunneling curtain grouting Technical Field

[0001] This invention belongs to the field of grouting technology in geotechnical engineering, specifically relating to an in-situ test method based on shield tunneling curtain grouting. Background Technology

[0002] In recent years, tunnel construction has been booming, and the development of underground space has been accelerating. Grouting technology plays a crucial role in tunnel construction. Among various grouting techniques, sleeve valve grouting is widely used in foundation reinforcement and water-stop curtains in tunnel construction due to its high construction flexibility, deep grouting depth, and ability to perform multi-point, quantitative grouting in the soil layer. Furthermore, sleeve valve grouting allows for better control of the grouting range and pressure, enables repeated grouting, and largely avoids grout leakage and cross-contamination.

[0003] Numerous scholars have conducted extensive research on sleeve valve pipe grouting reinforcement technology. Document CN116892210A discloses a sleeve valve pipe grouting device and method, which simultaneously drills and grouts, significantly improving grouting efficiency. Document CN217629921U discloses a sleeve valve pipe grouting auxiliary directional device, solving the problem of connection between the grouting device body and the soil. Document CN114718046A discloses a sleeve valve pipe grouting structure and its construction method for deep fill layers. This method is suitable for high-pressure grouting operations, and the sleeve valve pipe is quickly and tightly assembled, facilitating grouting in deep fill layers. Document CN112813959A discloses a sleeve valve pipe grouting device and method based on an elastic membrane, significantly improving the reinforcement and water-stopping effect of the strata. Document CN105714764A discloses a construction method for deep-hole sleeve valve pipe grouting at the surface of tunnels, detailing the sleeve valve pipe grouting process; however, the grouting device described herein cannot avoid the drawback of grout leakage from the sleeve valve pipe orifice during the grouting process.

[0004] Based on existing research, despite the publication of numerous technological achievements, in terms of design, there is no unified standard for curtain grouting pipeline design methods. Regarding grouting construction, current technologies are largely limited to improvements in grouting devices and process optimization. The developed devices and processes still cannot completely eliminate the risks of grout leakage from grouting holes and the ground surface. Furthermore, research on the ground response during grouting is relatively scarce, and the following technical challenges remain:

[0005] 1. There is no unified standard for the design of curtain grouting pipelines. The layout of the number of curtain grouting pipeline rings and the number of pipelines per ring are mostly based on experience and lack theoretical calculation basis. This affects the reinforcement range of the surrounding rock in the shield tunneling section and the quality of grout junction caused by excessive pipeline spacing. Consequently, it has a significant impact on the reinforcement and water-stopping effect of the surrounding rock in the tunneling section and cannot provide a stable water-free environment for subsequent shield tunneling.

[0006] 2. The force exerted by the grout pressure on the stratum or adjacent structures during the grouting process is not yet clear. In actual grouting construction, the grout pressure may damage adjacent structures. There are certain limitations in how to dynamically adjust parameters such as grouting pressure and grouting volume according to the stratum pressure response.

[0007] 3. During the grouting process, grout leaks from the sleeve valve pipe orifice and the ground, preventing the grout from being injected into the stratum to be reinforced, thus greatly reducing the reinforcement and water-stopping effect.

[0008] 4. Conventional grouting using a single water-filled grout plug core tube cannot accurately control the grout outlet position, resulting in uneven grouting reinforcement effect.

[0009] 5. It is difficult to know whether the formation temperature will rise due to the heat of hydration of the grout after the grouting is completed. Summary of the Invention

[0010] The purpose of this invention is to address the aforementioned problems and shortcomings of existing technologies by designing an in-situ testing method for shield tunneling with curtain grouting. This method optimizes the number and length of the curtain grouting pipeline layout to ensure the grouting reinforcement range meets design requirements and that the grout injected from each pipeline completely overlaps, fully filling the surrounding rock's water channels and providing a stable, water-free environment for subsequent excavation. Based on the curtain grouting pipeline layout, an in-situ grouting test is designed. Pressure and temperature sensors are deployed to monitor in real-time the formation pressure response caused by grout pressure and the formation temperature changes caused by grout hydration heat during the grouting process. The method investigates the laws governing the increase and dissipation of formation pressure and temperature, and then adjusts the grouting parameters in real-time based on the monitoring data to meet actual engineering requirements.

[0011] An in-situ test method based on shield tunneling curtain grouting includes the following steps:

[0012] S1: Curtain grouting pipelines are installed for the first and subsequent shield bodies. The curtain grouting pipelines for each ring of the first shield body are arranged radially from the inner wall of the shield shell to the surrounding rock of the docking section. The ends of the curtain grouting pipelines for each ring of the first shield body are on the same cross-section. The curtain grouting pipelines of the subsequent shield body pass through this cross-section, and this cross-section is in contact with the shield shell of the subsequent shield body. m rings of curtain grouting pipelines are provided with m rows of grouting holes. At the same time, multiple monitoring holes are provided.

[0013] S2: Install sensors in the monitoring holes. After the sensors are installed, connect them to the data acquisition device to collect formation response parameters during the subsequent grouting process.

[0014] S3: Use sleeve valve pipe as grouting pipeline for grouting of the formation;

[0015] S4: Drill holes according to the designed location of the grouting holes and complete the lowering of the sleeve valve tube;

[0016] S5: After the sleeve valve tube is lowered, the gap between the outer side of the tube wall and the formation is filled with casing material;

[0017] S6: After the casing material has been consolidated and strengthened, perform sleeve valve pipe retraction grouting;

[0018] S7: Real-time monitoring of sensor data during grouting;

[0019] S8: After grouting is completed, the holes are sealed.

[0020] S9: Once the sensor output data remains stable, remove the data acquisition device to complete the test.

[0021] Furthermore, the grouting pipeline of the pre-connected shield tunnel body is constrained by the grouting diffusion radius: L c ≤RL a ≥[D]-R

[0022] Among them, L c R represents the vertical distance from the end point of the innermost grouting pipe of the shield body to the shield body during the docking process, and L represents the grouting diffusion radius. a [D] indicates the vertical distance from the end point of the outermost pipeline of the shield body grouting in the first shield to be connected, and [D] indicates the maximum thickness of the surrounding rock grouting reinforcement.

[0023] Furthermore, the grouting pipeline of the pre-connected shield tunnel body is constrained by the width of the lateral surrounding rock grouting reinforcement: U≥[U]

[0024] Where U represents the distance from the end face of the m-ring curtain grouting pipeline to the docking surface, and [U] represents the minimum lateral surrounding rock grouting reinforcement width.

[0025] Preferably, the number of grouting pipes n per loop is subject to the following constraints: b A ≤2R (R 盾构 +L a )×πθ / 180°≤2R θ=360° / n

[0026] Among them, b A R represents the circumferential spacing of the outermost pipes in the curtain grouting system. 盾构 L represents the radius of the tunnel boring machine. aθ represents the vertical distance from the end point of the outermost pipe in the curtain grouting to the shield body, and θ represents the angle between the end point of the pipe and the end point of the adjacent pipe in the same circle on the cross surface of the pipe end point.

[0027] Preferably, the lateral spacing of the grouting holes simulates the circumferential arrangement spacing of the grouting pipes on the end face of the grouting pipes of the first shield body; the longitudinal spacing of the grouting holes simulates the radial arrangement spacing of the grouting pipes on the end face of the grouting pipes of the first shield body.

[0028] Furthermore, one monitoring hole simulates the position of the shield body in the docking section, while other monitoring holes are set within the range of the grouting holes. The distance W between the monitoring holes and the grouting holes satisfies: 0.5R≤W≤1.5R

[0029] Where R represents the grouting diffusion radius, and W represents the design distance between the monitoring hole and the grouting hole.

[0030] Preferably, the sensors in step S2 include a pore water pressure gauge, an earth pressure cell, and a temperature sensor, satisfying the following equations: Hp=γ·h Hw1=ξ1·h Hw2=ξ2·h

[0031] Where Hp represents the vertical distance gradient of the pore water pressure gauge, Hw1 and Hw2 represent the vertical distance gradients of the earth pressure cell and the temperature sensor, respectively, h represents the spacing between the slurry outlet holes opened on the sleeve valve tube wall, γ represents the vertical distribution coefficient of the pore water pressure gauge, and ξ1 and ξ2 represent the vertical distribution coefficients of the earth pressure cell and the temperature sensor, respectively.

[0032] Furthermore, the area of ​​the grout outlet in the shield docking section is the same as the area of ​​the overflow grout outlet during the in-situ test, thereby achieving coordinated matching between the grouting speed and the grouting speed of the docking section during the in-situ test.

[0033] The grouting retreat distance of the shield tunneling section is S, the spacing of the grout outlet holes on the sleeve valve pipe wall is h, and the sleeve valve pipe wall has S / h rows of cross-shaped holes, with 4 overflow holes in a single row. The opening diameter of the sleeve valve pipe grout outlet holes must satisfy the following relationship to ensure that the grout outlet hole area of ​​the shield tunneling section is the same as the overflow hole area during the in-situ test:

[0034] Where d represents the diameter of the test slurry outlet opening, and A S The area of ​​the grout outlet holes in the curtain grouting section of the docking segment is represented by S, the grouting back step distance of the shield docking segment is represented by h, and the spacing of the grout outlet holes opened on the sleeve valve pipe wall is represented by h.

[0035] Furthermore, the grouting volume is designed to satisfy the following relationship: Q=V*n*ɑ*β V=πR 2 *H

[0036] Where Q represents the designed grouting volume, V represents the volume of the reinforced soil, R represents the grouting diffusion radius, H represents the grouting section depth, n represents the porosity of the reinforced soil, α represents the soil filling coefficient, and β represents the grout loss coefficient.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The in-situ test method based on shield docking curtain grouting provided by the present invention achieves complete connection of grout from each pipeline by designing the number and length of curtain grouting pipelines, and uses the minimum number of curtain grouting pipelines to ensure that the grouting reinforcement range of the surrounding rock meets the design requirements, fully filling the water channels of the surrounding rock, and providing a stable waterless environment for subsequent excavation.

[0039] (2) The in-situ test method based on shield tunneling curtain grouting provided by this invention innovatively monitors the formation pressure response caused by grout pressure and the formation temperature change caused by grout hydration heat in real time by drilling boreholes with preset pressure and temperature sensors in the grouting area. This monitoring method clarifies the laws governing the increase and dissipation of formation pressure and temperature during grouting, revealing the mechanism of grouting reinforcement. It provides data support for the selection of grouting parameters in formation grouting reinforcement projects, and further provides a reference for the analysis of external forces and the design of temperature boundary conditions for subsequent actual engineering grouting construction on adjacent structures.

[0040] (3) The in-situ test method based on shield docking curtain grouting provided by the present invention summarizes the variation law of ground pressure along distance and the pressure distribution characteristics of different strata by setting monitoring sensors at different distances from the grouting point in the horizontal direction and setting monitoring sensors at different depths and different strata in the vertical direction.

[0041] (4) The in-situ test method based on shield docking curtain grouting provided by the present invention is to design a double water bladder type grout stop plug grouting core tube so that the grout is injected into the stratum from the overflow hole between the two water stop bladders. After the single meter of grouting is completed, the double water bladder type grout stop plug grouting core tube is pulled back 1m. During the overall retreat process, the overflow hole is always kept between the two water stop bladders, and the grouting position and grouting speed are precisely controlled to achieve uniform stratum reinforcement.

[0042] (5) The in-situ test method for shield tunneling curtain grouting provided by this invention optimizes the sealing process of the grouting hole in the sleeve valve pipe and the protection process of the sealing device through step S33. This solves the problem of grout leakage from the sleeve valve pipe orifice during grouting while ensuring airtightness.

[0043] (6) The in-situ test method based on shield docking curtain grouting provided by the present invention uses the skip-hole grouting method in step S61 to carry out double liquid grouting pre-reinforcement, which solves the problems of surface grouting and grout leakage in monitoring holes. Attached Figure Description

[0044] Figure 1 is a plan view of the curtain grouting pipeline layout of the present invention;

[0045] Figure 2 is a cross-sectional view of the curtain grouting pipeline layout of the present invention;

[0046] Figure 3 is a plan view of the grouting holes and monitoring holes of the present invention;

[0047] Figure 4 is a cross-sectional view of the grouting hole and monitoring hole location of the present invention;

[0048] Figure 5 is a schematic diagram of grouting using the double water bladder grout stop plug type grouting core tube of the present invention;

[0049] Figure 6 is a design diagram of the sleeve valve tube opening of the present invention.

[0050] In the diagram: 1-Connecting the first shield body, 2-Connecting the second shield body, 3-A row of grouting pipes, 4-B row of grouting pipes, 5-C row of grouting pipes, 6-D row of grouting pipes, 7-1-A row of grouting holes, 7-2-B row of grouting holes, 7-3-C row of grouting holes, 7-4-D row of grouting holes, 8-1-Y4 monitoring hole, 8-2-Y3 monitoring hole, 8-3-Y2 monitoring hole, 8-4-Y1 monitoring hole, 9-1-Temperature sensor, 9-2-Earth pressure cell, 10-Pore water pressure gauge, 11-Grouting core pipe, 12-Sleeve valve pipe, 13-Grouting outlet hole, 14-Grouting area, 15-Rubber sleeve, 16-Protective steel wire, 17-Water injection hole, 18-Grouting hole, 19-PE pipe, 20-Shell material. Detailed Implementation

[0051] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] This invention designs an in-situ test method based on shield tunneling curtain grouting, comprising the following steps:

[0053] S1: Design an in-situ test based on the layout of the curtain grouting pipeline in the shield tunnel docking section;

[0054] S2: Surface boreholes are drilled according to the design location of the monitoring boreholes to install sensors. After the sensors are installed, they are connected to a data acquisition device for collecting stratum response parameters during subsequent grouting.

[0055] S3: Seamless steel pipes are used to process the sleeve valve pipe 12, and the processed sleeve valve pipe 12 is used as the grouting pipeline for grouting of the formation.

[0056] S4: Drill holes according to the designed location of the grouting holes and complete the lowering of sleeve valve tube 12;

[0057] S5: After the sleeve valve tube 12 is lowered, the gap between the outer side of the tube wall and the formation is filled with the casing material 20;

[0058] S6: After the shell material 20 has been consolidated and strengthened, the double water bladder grout stop plug type grouting core tube is lowered. Water is injected through the water injection hole 17 to pressurize and fix the grouting core tube and prevent the grout from flowing up along the sleeve valve tube. The sleeve valve tube 12 is then retracted for grouting.

[0059] S7: Real-time monitoring of formation pressure and temperature response during grouting process via sensor output data;

[0060] S8: After grouting is completed, the holes are sealed.

[0061] S9: Once the sensor output data remains stable, remove the data acquisition device to complete the test.

[0062] The installation of the grouting pipeline for the shield tunnel docking section in step S1 specifically includes the following steps:

[0063] S11: Design m-ring curtain grouting pipelines, with n grouting pipelines in each ring.

[0064] S12: The number of curtain grouting pipeline loops m is mainly affected by the pipeline angle α, the designed grouting diffusion radius R, and the designed maximum surrounding rock grouting reinforcement thickness [D]. The determination method is mainly based on the following formula:

[0065] (1) Vertical distance L from the end point of the innermost pipeline of the curtain grouting to the shield body c ≤R, thus ensuring that there is no blank area for grout on the outside of the shield body of the docking section, and the surrounding rock can be completely reinforced by grout.

[0066] (2) Vertical distance L from the end point of the outermost pipe of the curtain grouting to the shield body a ≥[D]-R, thereby ensuring that the thickness of the surrounding rock reinforcement meets the load-bearing and water-stopping requirements during subsequent excavation.

[0067] (3) The distance from the end section of the m-ring curtain grouting pipeline to the docking surface is U≥[U], thereby ensuring the width of the surrounding rock grouting reinforcement of the docking section to block lateral water.

[0068] [D] represents the maximum thickness of the surrounding rock grouting reinforcement, with a value range of 3 to 5 m.

[0069] [U] represents the minimum lateral grouting reinforcement width. The value ranges from 2 to 3 meters.

[0070] S13: The number of grouting pipes per ring of the curtain grouting system, n, is mainly determined by the circumferential spacing b at the end point of the outermost ring of the curtain grouting pipes. A The influence of this method is mainly determined based on the following formula: b A ≤2R (R 盾构 +L a )×πθ / 180°≤2R θ=360° / n

[0071] Where: b A R represents the circumferential spacing of the outermost pipes in the curtain grouting system. 盾构 θ represents the radius of the tunnel boring machine, and θ represents the angle between the endpoints of adjacent pipelines within the same circle on the cross-section of the pipeline endpoint.

[0072] S14: Based on the design of m rows of grouting holes in the m-ring curtain grouting pipeline of the shield docking section, n′ of grouting holes are designed in each row. In order to make the in-situ test more consistent with the grouting effect of the curtain grouting group and meet certain economic requirements, n′ = 3 is designed. The lateral spacing of the grouting holes simulates the circumferential arrangement spacing of the grouting pipeline on the end face of the grouting pipeline of the shield body 1 of the docking pilot shield, that is, the lateral spacing of the grouting holes is equal to the circumferential arrangement spacing. The longitudinal spacing of the grouting holes simulates the radial arrangement spacing of the grouting pipeline on the end face of the grouting pipeline of the shield body 1 of the docking pilot shield, that is, the longitudinal spacing of the grouting holes is equal to the radial arrangement spacing. The lateral spacing represents the distance between adjacent grouting holes in the lateral direction in Figure 3, and the longitudinal spacing represents the distance between adjacent rows of grouting holes in the longitudinal direction in Figure 3.

[0073] S15: To monitor the changes in formation pressure and temperature during grouting, four monitoring holes are designed to house temperature sensors 9-1, earth pressure cells 9-2, and pore water pressure gauges 10. Based on experience, each monitoring hole is equipped with 10 pore water pressure gauges 10, 5 temperature sensors 9-1, and 5 earth pressure cells 9-2. Monitoring hole Y1 8-4 simulates the shield position of the docking section. Within the range of the four rows of grouting holes, three monitoring holes are set: Y2 8-3, Y3 8-2, and Y4 8-1. The design spacing W between the monitoring holes and the grouting holes is considered to have different values, with W ranging from (0.5R to 1.5R), where R represents the grout diffusion radius. This design distance enables monitoring of pressure and temperature responses at different horizontal distances.

[0074] S16: Multiple sets of data on the relationship between monitoring pressure and monitoring distance are obtained by setting monitoring sensors at multiple gradient distances from the grouting point in each monitoring hole. The functional relationship between the two is obtained by analysis, and the pressure change during the distance gradient process is determined.

[0075] S17: The soil around the shield tunnel section is composed of medium-coarse sand, fine sand and silty clay. Therefore, the soil layers within the in-situ grouting depth range are medium-coarse sand, fine sand and silty clay, respectively, to ensure the consistency of the grouting layers.

[0076] For example, Figures 1 and 2 are based on the specific setting of m=4. The shield docking section is designed with 4 rings of curtain grouting pipes, totaling 156 pipes. The shield body 1 of the first docking shield is designed with 3 rings, and the shield body 2 of the second docking shield is designed with 1 ring. The curtain grouting pipes are arranged in a radial pattern from the inner wall of the shield shell towards the surrounding rock of the docking section at 4 different angles. The ends of the 13 rings of grouting pipes of the first docking shield body are on the same cross-section, and this cross-section can capture the position of 1 ring of grouting pipes and the shield shell of the second docking shield body 2. The specific positions are shown in Figures 1 and 2. The shield body 1 of the first docking shield body is equipped with 3 rows of grouting pipes, namely the curtain grouting A row of grouting pipes 3, the curtain grouting B row of grouting pipes 4, and the curtain grouting C row of grouting pipes 5. The shield body 2 of the second docking shield body is equipped with 1 row of grouting pipes, namely the curtain grouting D row of grouting pipes 6.

[0077] Since current technology makes it difficult to simulate the curtain grouting test of the shield docking section in a full-state underground environment, simulating the effect of the curtain grouting process on the shield body through surface grouting is the most effective method. The curtain grouting of the docking section adopts a retreating grouting process, and the distance between the grouting point and the shield shell is gradually changing. However, current surface drilling and grouting technologies can only be carried out vertically, making it impossible to simulate the gradual distance change. Therefore, based on the pipe and shield shell position on the end cross-section of the three rings of grouting pipes of the shield body 1 of the docking pilot, a local in-situ grouting pipe distribution pattern of 12 grouting pipes in three circumferential rows and four radial rings was designed. The gradual distance was simulated by setting up monitoring sensors at multiple distances from the grouting points. By deploying a large number of sensors and analyzing the changes in sensor parameters at the distances from the grouting points, the change patterns were summarized, and curves of distance versus monitoring parameters were plotted to achieve the analysis of the gradual distance.

[0078] As shown in Figure 3, according to the design of the grouting pipelines of the four-ring curtain of the shield docking section, there are four rows of grouting holes, with three holes in each row, for a total of 12 vertical grouting holes: A row grouting pipeline 3 is equipped with A row grouting holes 7-1: grouting hole Z10, grouting hole Z11 and grouting hole Z12; B row grouting pipeline 4 is equipped with B row grouting holes 7-2: grouting hole Z7, grouting hole Z8 and grouting hole Z9; C row grouting pipeline 5 is equipped with C row grouting holes 7-3: grouting hole Z4, grouting hole Z5 and grouting hole Z6; D row grouting pipeline 6 is equipped with D row grouting holes 7-4: grouting hole Z1, grouting hole Z2 and grouting hole Z3.

[0079] To monitor changes in ground pressure and temperature during grouting, four monitoring holes were designed to house a temperature sensor 9-1, an earth pressure cell 9-2, and a pore water pressure gauge 10: monitoring hole Y1 8-4, monitoring hole Y2 8-3, monitoring hole Y3 8-2, and monitoring hole Y4 8-1. Monitoring hole Y1 8-4 simulates the position of the shield body in the docking section. Within the range of the four rows of grouting holes, three monitoring holes—Y2 8-3, Y3 8-2, and Y4 8-1—were installed. Here, the grouting hole range refers to the area enclosed by the outermost grouting holes. As shown in Figure 3, the grouting hole range refers to the area enclosed by grouting holes Z1, Z2, Z3, Z6, Z9, Z12, Z11, Z10, Z7, and Z4. The design spacing W between the monitoring hole and the grouting hole is designed to have different values, with W ranging from 0.5R to 1.5R, where R represents the grouting diffusion radius. This design distance enables the monitoring of pressure and temperature response at different distances in the horizontal direction.

[0080] The soil around the shield tunnel section is composed of medium-coarse sand, fine sand and silty clay. Therefore, the soil layers within the in-situ grouting depth range are medium-coarse sand, fine sand and silty clay to ensure the consistency of the grouting layers, as shown in Figure 4.

[0081] Furthermore, the specific steps for drilling the monitoring hole and installing the sensor in step S2 are as follows:

[0082] S21: The monitoring holes are drilled using mud slurry wall protection to lay the sensors in place;

[0083] S22: Tie and fix the pore water pressure gauge 10, earth pressure box 9-2, and temperature sensor 9-1 to the steel frame and lower them into the grouting area 14 of the stratum.

[0084] S23: The vertical distance gradient of the pore water pressure gauge 10 is Hp, with a value range of 2-3m; the vertical distance gradient between the soil pressure cell 9-2 and the temperature sensor 9-1 is Hw, with a value range of 4-6m, to realize pressure response monitoring at different depths in the vertical direction;

[0085] Furthermore, the vertical distance gradients of the pore water pressure gauge 10, the earth pressure cell 9-2, and the temperature sensor 9-1 satisfy the following relationships: Hp=γ·h Hw1=ξ1·h Hw2=ξ2·h

[0086] Where Hp represents the vertical distance gradient of the pore water pressure gauge, Hw1 and Hw2 represent the vertical distance gradients of the earth pressure cell and the temperature sensor, respectively, h represents the spacing between the slurry outlet holes opened on the sleeve valve tube wall, γ represents the vertical distribution coefficient of the pore water pressure gauge, and ξ1 and ξ2 represent the vertical distribution coefficients of the earth pressure cell and the temperature sensor, respectively.

[0087] S24: After the sensor is lowered, coarse sand and clay balls are used to backfill the gaps in the monitoring holes. Multiple backfillings are used to ensure that the gaps are filled densely. After the stratum is stable and dense, the sensor signal value is cleared to zero. This allows for a clearer understanding of the changes in stratum pressure and temperature during the grouting process.

[0088] Furthermore, the processing of the sleeve valve tube 12 in step S3 includes the following steps:

[0089] S31: The sleeve valve tube 12 includes several sleeve valve sub-tubes, which are connected by a connecting sleeve. The sleeve valve sub-tubes are made of seamless steel pipe with an outer diameter of 60mm and a wall thickness of 3.5mm. The connecting sleeve is made of seamless steel pipe with a length of 30cm, an outer diameter of 76mm and a wall thickness of 7mm.

[0090] S32: As shown in Figure 6, the sleeve valve pipe 12 hole wall adopts a cross-shaped symmetrical opening form as the grout outlet hole 13, the opening diameter d is 8mm, the number of openings in each cross section is 4, the grouting back step distance of the shield docking section is 1000mm, therefore the vertical opening spacing h of the sleeve valve pipe 12 hole wall is 500mm.

[0091] Furthermore, in order to achieve coordinated matching between the grouting speed during the in-situ test and the grouting speed of the docking section, it is necessary to ensure that the area of ​​the grout outlet hole 13 in the shield docking section is the same as the area of ​​the overflow hole during the in-situ test. Correspondingly, the retreat step distance S needs to be opened in S / h rows of cross-shaped holes on the wall of the sleeve valve pipe 12, with 4 overflow holes in a single row, and the total area of ​​the overflow holes in a single row is 4*π(d / 2). 2 According to the principle of equal area, A S = 4*π(d / 2) 2 *S / h, therefore, the opening diameter of the slurry outlet 13 of the sleeve valve pipe 12 satisfies the following relationship:

[0092] Where d represents the diameter of the test slurry outlet hole 13, and A S S represents the area of ​​the grout outlet hole 13 in the curtain grouting section of the docking segment, S represents the grouting back step distance of the shield docking segment, and h represents the spacing of the grout outlet holes 13 opened on the wall of the sleeve valve pipe 12.

[0093] S33: The opening of the sleeve valve tube 12 is sealed by a nested rubber sleeve 15, and a protective steel wire 16 is welded 2-3 cm above and below the rubber sleeve 15 to prevent the sleeve valve tube 12 from scraping the hole wall during the lowering process and causing the rubber sleeve 15 to become misaligned. Finally, the rubber sleeve 15 is wrapped with electrical tape to ensure its sealing.

[0094] Preferably, step S4, drilling the grouting hole and lowering the sleeve valve tube 12, includes the following steps:

[0095] S41: Grouting holes are drilled using mud slurry wall protection, with the following sleeve valve pipe 12;

[0096] S42: After the grouting hole 18 is formed, the sleeve valve pipe 12 is lowered. To facilitate the injection of the casing material 20, a PE pipe 19 with an outer diameter of 20mm is tied and fixed to the wall of the sleeve valve pipe 12 and lowered into the grouting hole 18 together. The bottom of the PE pipe 19 is positioned above the bottom of the sleeve valve pipe 12. p Distance, h p Take a range of 2 to 3 meters.

[0097] Preferably, the filling of the casing material 20 in step S5 includes the following steps:

[0098] S51: The materials for the casing material 20 include water, cement and bentonite, with a water:cement:bentonite ratio of 2:1:1.

[0099] S52: Use a grouting pump to pump the casing material 20 to the bottom of the grouting hole 18 through the PE pipe 19, so that the casing material 20 completely replaces the mud in the hole from bottom to top, until the casing material 20 overflows to the ground along the gap between the outer wall of the sleeve valve pipe 12 and the stratum.

[0100] Step S6, grouting of sleeve valve pipe 12, includes the following steps:

[0101] S61: A skip-hole grouting method is used for pre-reinforcement with dual-component grout. Before formal grouting, dual-component grout is first applied to the outermost holes (grouting holes Z1, Z3, Z10, and Z12). This utilizes the rapid setting characteristic of dual-component grout to address surface grout leakage and grout leakage through monitoring holes. The dual-component grout mix ratio is: cement grout water-cement ratio of 1:1, and cement grout to water glass mass ratio of 1:1.

[0102] S62: Single-hole grouting adopts a backward segmented grouting process, that is, grouting is carried out from the bottom of the hole in the grouting area 14, as shown in Figure 5. The grouting core tube 11 with double water bladder grout stop plug is designed to perform fixed-point grouting. The backward step distance S is 1m. After the first grouting section is completed, the grouting core tube is retracted to carry out the grouting of the second grouting section. This cycle is repeated until the single-hole grouting operation is completed.

[0103] S63: A dual control standard combining grouting pressure and grouting volume is adopted. Grouting of this section of the hole is terminated when the grouting control pressure reaches the design test hole grouting pressure or the grouting volume reaches 1.5-2.0 times the design grouting volume. Then, the drill is withdrawn 2m, and so on, until the grouting of the hole is terminated.

[0104] Furthermore, the grouting volume is designed to satisfy the following relationship: Q=V*n*ɑ*β V=πR 2 *H

[0105] Where Q represents the designed grouting volume, V represents the volume of the reinforced soil, R represents the grouting diffusion radius, H represents the grouting section depth, n represents the porosity of the reinforced soil, α represents the soil filling coefficient with a value of 0.8, and β represents the grout loss coefficient with a value of 1.1.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An in-situ test method based on shield tunneling curtain grouting, characterized in that, Includes the following steps: S1: Curtain grouting pipelines are installed for the first and subsequent shield bodies. The curtain grouting pipelines for each ring of the first shield body are arranged radially from the inner wall of the shield shell to the surrounding rock of the docking section. The ends of the curtain grouting pipelines for each ring of the first shield body are on the same cross-section. The curtain grouting pipelines of the subsequent shield body pass through this cross-section, and this cross-section is in contact with the shield shell of the subsequent shield body. m rings of curtain grouting pipelines are provided with m rows of grouting holes. At the same time, multiple monitoring holes are provided. S2: Install sensors in the monitoring holes. After the sensors are installed, connect them to the data acquisition device to collect formation response parameters during the subsequent grouting process. S3: Use sleeve valve pipe as grouting pipeline for grouting of the formation; S4: Drill holes according to the designed location of the grouting holes and complete the lowering of the sleeve valve tube; S5: After the sleeve valve tube is lowered, the gap between the outer side of the tube wall and the formation is filled with casing material; S6: After the casing material has been consolidated and strengthened, perform sleeve valve pipe retraction grouting; S7: Real-time monitoring of sensor data during grouting; S8: After grouting is completed, the holes are sealed. S9: Once the sensor output data remains stable, remove the data acquisition device to complete the test; The number of grouting pipelines per loop, n, is subject to the following constraints: b A ≤2R (R 盾构 +L a )×πθ / 180°≤2R θ = 360° / n Among them, b A R represents the circumferential spacing of the outermost pipes in the curtain grouting system. 盾构 R represents the radius of the tunnel boring machine, R represents the grouting diffusion radius, and L represents the radius of the tunnel boring machine. a θ represents the vertical distance from the end point of the outermost pipe in the curtain grouting to the shield body, and θ represents the angle between the end point of the pipe and the end point of the adjacent pipe in the same circle on the cross surface of the pipe end point.

2. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, The grouting pipeline of the pre-connected shield tunnel body is constrained by the grouting diffusion radius: L c ≤R L a ≥[D]-R Among them, L c R represents the vertical distance from the end point of the innermost grouting pipe of the shield body to the shield body during the docking process, and L represents the grouting diffusion radius. a [D] indicates the vertical distance from the end point of the outermost pipeline of the shield body grouting in the first shield to be connected, and [D] indicates the maximum thickness of the surrounding rock grouting reinforcement.

3. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, The grouting pipeline of the first-stage shield tunnel is constrained by the width of the lateral surrounding rock grouting reinforcement: U≥[U] Where U represents the distance from the end face of the m-ring curtain grouting pipeline to the docking surface, and [U] represents the minimum lateral surrounding rock grouting reinforcement width.

4. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, The lateral spacing of the grouting holes simulates the circumferential spacing of the grouting pipes on the end face of the grouting pipes of the first-stage shield body; the longitudinal spacing of the grouting holes simulates the radial spacing of the grouting pipes on the end face of the grouting pipes of the first-stage shield body.

5. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, One monitoring hole simulates the position of the shield body in the docking section, and other monitoring holes are set within the range of the grouting holes. The distance W between the monitoring holes and the grouting holes satisfies: 0.5R≤W≤1.5R Where R represents the grouting diffusion radius, and W represents the design distance between the monitoring hole and the grouting hole.

6. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, The sensors in step S2 include a pore water pressure gauge, an earth pressure cell, and a temperature sensor, satisfying the following equation: Hp=γ·h Hw1=ξ1·h Hw2=ξ2·h Where Hp represents the vertical distance gradient of the pore water pressure gauge, Hw1 and Hw2 represent the vertical distance gradients of the earth pressure cell and the temperature sensor, respectively, h represents the spacing between the slurry outlet holes opened on the sleeve valve tube wall, γ represents the vertical distribution coefficient of the pore water pressure gauge, and ξ1 and ξ2 represent the vertical distribution coefficients of the earth pressure cell and the temperature sensor, respectively.

7. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, The area of ​​the grout outlet in the shield docking section is the same as the area of ​​the overflow outlet during the in-situ test, thus achieving coordinated matching between the grouting speed during the in-situ test and the grouting speed of the docking section.

8. The in-situ test method based on shield tunneling curtain grouting according to claim 7, characterized in that, The grouting retreat distance of the shield tunneling section is S, the spacing of the grout outlet holes on the sleeve valve pipe wall is h, and the sleeve valve pipe wall has S / h rows of cross-shaped holes, with 4 overflow holes in a single row. The opening diameter of the sleeve valve pipe grout outlet holes must satisfy the following relationship to ensure that the grout outlet hole area of ​​the shield tunneling section is the same as the overflow hole area during the in-situ test: Where d represents the diameter of the test slurry outlet opening, and A S The area of ​​the grout outlet holes in the curtain grouting section of the docking segment is represented by S, the grouting back step distance of the shield docking segment is represented by h, and the spacing of the grout outlet holes opened on the sleeve valve pipe wall is represented by h.

9. The in-situ test method based on shield tunneling curtain grouting according to claim 1, characterized in that, The grouting volume is designed to satisfy the following relationship: Q = V * n * ɑ * β V=πR 2 *H Where Q represents the designed grouting volume, V represents the volume of the reinforced soil, R represents the grouting diffusion radius, H represents the grouting section depth, n represents the porosity of the reinforced soil, α represents the soil filling coefficient, and β represents the grout loss coefficient.

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