In-situ test method based on shield butt joint curtain grouting

Abstract

The invention discloses an in-situ test method based on shield butt joint curtain grouting, which realizes complete circle crossing of grout injected from each pipeline by designing the arrangement circle number and length of curtain grouting pipelines, and ensures that the surrounding rock grouting reinforcement range meets the design requirement by adopting the minimum number of curtain grouting pipelines, so that a surrounding rock water system channel is fully filled, and the construction period is shortened. A stable water-free environment is provided for subsequent excavation, and the problems that in the prior art, a theoretical calculation basis is lacked, the shield butt joint section surrounding rock reinforcing range is affected, the slurry crossing quality problem is caused by too large pipeline spacing arrangement, and the reinforcing and water stopping effect of butt joint section surrounding rock is remarkably affected are effectively solved. Meanwhile, a sensor is preset in a drilling hole within the grouting range, formation pressure response caused by grout pressure and formation temperature change caused by grout hydration heat in the grouting process are monitored in real time, and data support is provided for selection of grouting parameters in a formation grouting reinforcement project.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering grouting, and in particular relates to an in-situ test method based on shield butt-jointed curtain grouting. Background Art

[0002] In recent years, tunnel construction has been in full swing, and the development of underground space has been accelerating. Grouting technology plays a vital role in the tunnel construction process. Among the many grouting technologies, the sleeve valve tube grouting method is widely used in foundation reinforcement, water-stop curtains and other aspects during tunnel construction due to its high construction flexibility, deep grouting depth, and the ability to achieve multi-point and quantitative grouting in the soil layer. In addition, the sleeve valve tube grouting method can better control the grouting range and grouting pressure, realize repeated grouting, and largely avoid the phenomenon of grouting and grouting.

[0003] Many scholars have conducted extensive research on sleeve valve tube grouting reinforcement technology. Document CN116892210A discloses a sleeve valve tube grouting device and a grouting method, which have the functions of simultaneous drilling and grouting, greatly improving the efficiency of grouting; Document CN217629921U discloses a sleeve valve tube grouting auxiliary orientation device, which solves the problem of connection between the grouting device body and the soil; Document CN114718046A discloses a sleeve valve tube grouting structure for deep fill layers and a construction method thereof, which is suitable for high-pressure grouting operations, and the sleeve valve tube is assembled quickly and tightly, which is conducive to grouting of deep fill layers; Document CN112813959A discloses a sleeve valve tube grouting device and a grouting method based on an elastic membrane, which significantly improves the reinforcement and water-stopping effect of the stratum; Document CN105714764A discloses a tunnel surface deep hole sleeve valve tube grouting construction method, and elaborates on the process flow of sleeve valve tube grouting, but the grouting device is difficult to avoid the disadvantage of grouting from the sleeve valve tube orifice during grouting.

[0004] Based on existing research, although a large number of technical achievements have been made public, in terms of design, there is no unified standard for the design method of curtain grouting pipelines. In terms of grouting construction, current technologies are mostly limited to the improvement of grouting devices and process optimization. The developed devices and processes still cannot completely avoid the risks of grouting holes and surface grouting. There are relatively few results on the research of formation response during grouting, and there are the following technical difficulties:

[0005] 1. There is no unified standard for the design of curtain grouting pipelines. How to layout the number of curtain grouting pipeline circles and the number of pipelines in each circle are mostly limited to the experience level, and lack of theoretical calculation basis, which affects the reinforcement range of the surrounding rock of the shield docking section, as well as the slurry intersection quality problems caused by the excessive spacing of the pipelines, which in turn has a significant impact on the reinforcement and water-stopping effect of the surrounding rock of the docking section, and cannot provide a stable water-free environment for subsequent shield excavation.

[0006] 2. The effect of slurry pressure on the stratum or adjacent structures during the grouting process is still unclear. In actual grouting construction, the slurry pressure may damage the adjacent structures. There are certain limitations on how to dynamically adjust parameters such as grouting pressure and grouting volume according to the stratum pressure response.

[0007] 3. During the grouting process, slurry is bubbling out from the sleeve valve pipe hole and the ground, which makes it impossible to inject the slurry into the stratum to be reinforced, greatly reducing the reinforcement and water-stopping effect.

[0008] 4. The conventional use of a single water bag type stop plug grouting core tube for grouting cannot accurately control the slurry outlet position, resulting in uneven grouting reinforcement effect.

[0009] 5. It is difficult to know whether the formation temperature rises due to the heat of hydration of the slurry after the grouting is completed. Summary of the invention

[0010] The purpose of the present invention is to address the above-mentioned problems existing in the prior art, overcome the shortcomings of the prior art, and design an in-situ test method based on shield-jointed curtain grouting. By optimizing the number of circles and length of the curtain grouting pipeline layout, the surrounding rock grouting reinforcement range meets the design requirements, and the slurry injected from each pipeline is completely circled, fully filling the surrounding rock water system channel, and providing a stable water-free environment for subsequent excavation. According to the layout of the curtain grouting pipeline, an in-situ grouting test is designed. By laying pressure and temperature sensors, the formation pressure response caused by the slurry pressure during the grouting process and the formation temperature changes caused by the hydration heat of the slurry are monitored in real time, and the formation pressure and temperature growth and dissipation laws are explored, and then the grouting parameters are adjusted in real time according to the monitoring data to meet the actual engineering requirements.

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

[0012] S1: Curtain grouting pipelines are set up for the butt-jointed shield body of the leading shield and the butt-jointed shield body of the trailing shield, wherein the curtain grouting pipelines of each circle of the butt-jointed shield body are arranged in a radial shape from the inner wall of the shield shell to the surrounding rock of the butt-jointed section, and the ends of the curtain grouting pipelines of each circle of the butt-jointed shield body are on the same cutting plane, and the curtain grouting pipelines of the trailing shield pass through the cutting plane, and the cutting plane is in contact with the shield shell of the butt-jointed shield body of the trailing shield, and m rows of grouting holes are set up for m circles of curtain grouting pipelines respectively, and multiple monitoring holes are set up at the same time;

[0013] S2: burying sensors in the monitoring holes, and connecting them to data acquisition devices after the sensors are buried to prepare for the acquisition of formation response parameters during the subsequent grouting process;

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

[0015] S4: Drill holes according to the designed position of the grouting holes and lower the sleeve valve pipe;

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

[0017] S6: After the shell material has been consolidated to a certain strength, the sleeve valve pipe is grouted backward;

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

[0019] S8: After the grouting is completed, the hole is sealed;

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

[0021] Furthermore, the grouting pipeline of the shield body of the first shield is constrained by the grouting diffusion radius:

[0022] L c ≤R

[0023] L a ≥[D]-R

[0024] Among them, L c It indicates the vertical distance between the end point of the innermost pipeline of the shield body grouting of the first shield and the shield body, R indicates the grouting diffusion radius, L a It indicates the vertical distance between the end point of the outermost pipeline of the shield body grouting of the preceding shield and the shield body, and [D] indicates the maximum surrounding rock grouting reinforcement thickness.

[0025] Furthermore, the grouting pipeline of the shield body of the first shield is constrained by the width of the lateral surrounding rock grouting reinforcement:

[0026] U≥[U]

[0027] Wherein, U represents the distance from the end section of the m-circle curtain grouting pipeline to the butt joint surface, and [U] represents the minimum lateral surrounding rock grouting reinforcement width.

[0028] Preferably, the number n of grouting pipelines per circle is subject to the following constraints:

[0029] b A ≤2R

[0030] (R 盾构 +L a )×πθ / 180°≤2R

[0031] θ=360° / n

[0032] Among them, b A Indicates the circumferential spacing of the outermost pipelines of curtain grouting, R 盾构 Indicates the radius of the shield, L aIt indicates the vertical distance between the outermost pipeline end point of curtain grouting and the shield body, and θ indicates the angle between the adjacent pipeline end points in the same circle on the section of the pipeline end point.

[0033] Preferably, the transverse spacing of the grouting holes simulates the circumferential arrangement spacing of the grouting pipelines on the end section of the grouting pipelines docking the shield body of the preceding shield machine; the longitudinal spacing of the grouting holes simulates the radial arrangement spacing of the grouting pipelines on the end section of the grouting pipelines docking the shield body of the preceding shield machine.

[0034] Furthermore, one monitoring hole simulates the shield body position of the docking section, and other monitoring holes are set within the grouting hole range. The spacing W between the monitoring holes and the grouting holes satisfies:

[0035] 0.5R≤W≤1.5R

[0036] Where R represents the grouting diffusion radius, and W represents the design distance between the monitoring hole and the grouting hole.

[0037] Preferably, the sensor in step S2 includes a pore water pressure gauge, an earth pressure cell, and a temperature sensor, satisfying the following formula:

[0038] Hp=γ·h

[0039] Hw1=ξ1·h

[0040] Hw2=ξ2·h

[0041] Wherein, Hp represents the vertical distance gradient of the pore water pressure gauge, Hw1 and Hw2 represent the vertical distance gradients of the earth pressure box and the temperature sensor, respectively, h represents the spacing of the slurry outlet holes opened on the hole wall of the sleeve valve pipe, γ represents the vertical distribution coefficient of the pore water pressure gauge, ξ1 and ξ2 represent the vertical distribution coefficients of the earth pressure box and the temperature sensor, respectively.

[0042] Furthermore, the area of ​​the grouting holes in the shield joint section is the same as the area of ​​the overflow holes during the in-situ test, thereby achieving a coordinated match between the grouting speed during the in-situ test and the grouting speed of the joint section.

[0043] The step-back distance of grouting in the shield joint section is S, the spacing of the grouting holes opened on the sleeve valve pipe hole wall is h, the sleeve valve pipe wall is opened with S / h rows of cross holes, and 4 overflow holes in a single row. Then the diameter of the sleeve valve pipe grouting hole opening satisfies the following relationship to ensure that the grouting hole area of ​​the shield joint section is the same as the overflow hole area during the in-situ test:

[0044]

[0045] Where d is the diameter of the test slurry outlet hole, A S It represents the area of ​​the curtain grouting holes in the docking section, S represents the retreat distance of the grouting in the docking section of the shield, and h represents the spacing between the grouting holes opened on the hole wall of the sleeve valve pipe.

[0046] Furthermore, the designed grouting volume satisfies the following relationship:

[0047] Q=V*n*ɑ*β

[0048] V=πR 2 *H

[0049] Among them, Q represents the designed grouting volume, V represents the volume of the soil to be reinforced, R represents the grouting diffusion radius, H represents the depth of the grouting section, n represents the void ratio of the reinforced stratum soil, ɑ represents the stratum filling coefficient, and β represents the slurry loss coefficient.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The in-situ test method based on shield tunneling curtain grouting provided by the present invention realizes complete intersection of slurry injected from each pipeline by designing the number of circles and length of curtain grouting pipelines, and uses a minimum number of curtain grouting pipelines to ensure that the surrounding rock grouting reinforcement range meets the design requirements, fully fills the surrounding rock water system channel, and provides a stable water-free environment for subsequent excavation.

[0052] (2) The in-situ test method based on shield-jointed curtain grouting provided by the present invention innovatively monitors the formation pressure response caused by the slurry pressure and the formation temperature change caused by the hydration heat of the slurry in real time during the grouting process by presetting pressure and temperature sensors through drilling holes in the grouting area. This monitoring method clarifies the growth and dissipation rules of the formation pressure and temperature during the grouting process, and reveals the mechanism of action of grouting reinforcement. It provides data support for the selection of grouting parameters for formation grouting reinforcement projects, and further provides a reference for the analysis of external forces acting on adjacent structures and the design of temperature boundary conditions during subsequent actual engineering grouting construction.

[0053] (3) The in-situ test method based on shield-jointed curtain grouting provided by the present invention is to summarize the variation law of formation pressure along the distance and the pressure distribution characteristics of different formations by setting monitoring sensors at different distances from the grouting points in the horizontal direction and at different depths and in different formations in the vertical direction.

[0054] (4) The in-situ test method based on shield butt curtain grouting provided by the present invention designs a double-water bag type grouting plug grouting core tube so that the slurry is injected into the formation from the overflow hole between the two water-stop bags. After the single-meter grouting is completed, the double-water bag type grouting plug grouting core tube is retreated by 1m. During the overall retreat process, the overflow hole is always kept equal between the two water-stop bags, and the slurry discharge position and slurry discharge speed are accurately controlled to achieve uniform reinforcement of the formation.

[0055] (5) The in-situ test method based on shield-jointed curtain grouting provided by the present invention optimizes the sealing of the grouting holes opened by the sleeve valve pipe and the protection process of the sealing device through step S33. Under the premise of ensuring the sealing performance, the problem of grout bubbling from the sleeve valve pipe hole during the grouting process is solved.

[0056] (6) The in-situ test method based on shield tunneling curtain grouting provided by the present invention adopts the skip hole grouting method to perform double-liquid grouting pre-reinforcement through step S61, thereby solving the problems of grouting on the surface and grouting in the monitoring hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a plan view of the curtain grouting pipeline layout of the present invention;

[0058] Figure 2 It is a cross-sectional view of the curtain grouting pipeline layout of the present invention;

[0059] Figure 3 It is a plan view of the grouting holes and monitoring holes of the present invention;

[0060] Figure 4 It is a cross-sectional view of the grouting hole and the monitoring hole position of the present invention;

[0061] Figure 5 It is a schematic diagram of grouting of a double water bag stopper type grouting core tube of the present invention;

[0062] Figure 6 It is a sleeve valve pipe opening design drawing of the present invention.

[0063] In the figure: 1-docking with the shield of the preceding shield, 2-docking with the shield of the succeeding shield, 3-A row of grouting pipelines, 4-B row of grouting pipelines, 5-C row of grouting pipelines, 6-D row of grouting pipelines, 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-soil pressure box, 10-pore water pressure gauge, 11-grouting core pipe, 12-sleeve valve pipe, 13-slurry 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 DESCRIPTION

[0064] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The present invention designs an in-situ test method based on shield butt curtain grouting, which comprises the following steps:

[0066] S1: Design in-situ test according to the layout of curtain grouting pipelines in the shield joint section;

[0067] S2: Drilling holes on the ground according to the designed location of the monitoring hole to bury the sensor. After the sensor is buried, connect the data acquisition device to prepare for the acquisition of formation response parameters during the subsequent grouting process;

[0068] S3: using seamless steel pipe to process sleeve valve pipe 12 and using the processed sleeve valve pipe 12 as grouting pipeline to perform formation grouting;

[0069] S4: Drill holes according to the designed positions of the grouting holes and lower the sleeve valve pipe 12;

[0070] 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;

[0071] S6: After the casing material 20 has been consolidated to a certain strength, the double water bag stopper type grouting core pipe is lowered, water is injected through the water injection hole 17 to pressurize and fix the grouting core pipe and prevent the slurry from flowing up along the sleeve valve pipe, and the sleeve valve pipe 12 is grouted backward;

[0072] S7: Real-time monitoring of formation pressure and temperature response during grouting process through sensor output data;

[0073] S8: After the grouting is completed, the hole is sealed;

[0074] S9: When the sensor output data remains stable, remove the data acquisition device and complete the test.

[0075] The laying of the curtain grouting pipeline of the shield joint section in step S1 specifically includes the following steps:

[0076] S11: Design m circles of curtain grouting pipelines, with n number of grouting pipelines in each circle.

[0077] S12: The number of curtain grouting pipeline turns m is mainly affected by the pipeline angle ɑ, 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:

[0078] (1) The vertical distance L between the innermost pipe end point of curtain grouting and the shield c ≤R, so that there is no grout blank area outside the shield body of the docking section, and the surrounding rock can be completely reinforced by grout.

[0079] (2) The vertical distance L between the end point of the outermost pipeline of the curtain grouting and the shield a≥[D]-R, thereby ensuring that the surrounding rock reinforcement thickness can meet the bearing and water-stopping requirements during subsequent excavation.

[0080] (3) The distance from the end section of the m-circle curtain grouting pipeline to the butt joint surface is U ≥ [U], thereby ensuring the grouting reinforcement width of the surrounding rock in the butt joint section to block lateral water.

[0081] [D] represents the maximum surrounding rock grouting reinforcement thickness, ranging from 3 to 5m.

[0082] [U] represents the minimum lateral surrounding rock grouting reinforcement width. The value range is 2 to 3m.

[0083] S13: The number of curtain grouting pipelines per circle n is mainly affected by the annular spacing b of the end points of the outermost circle of curtain grouting pipelines. A The determination method is mainly based on the following formula:

[0084] b A ≤2R

[0085] (R 盾构 +L a )×πθ / 180°≤2R

[0086] θ=360° / n

[0087] Where: b A Indicates the circumferential spacing of the outermost pipelines of curtain grouting, R 盾构 represents the radius of the shield, and θ represents the angle between adjacent pipeline endpoints in the same circle on the section of the pipeline endpoint.

[0088] S14: According to the m-circle curtain grouting pipeline of the shield joint section, m rows of grouting holes are designed, and 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 holes of the joint section and meet certain economic efficiency, n′=3 is designed. The transverse spacing of the grouting holes simulates the circumferential arrangement spacing of the grouting pipelines on the end section of the grouting pipeline of the shield body 1 of the joint leading shield, that is, the transverse spacing of the grouting holes is equal to the circumferential arrangement spacing, and the longitudinal spacing of the grouting holes simulates the radial arrangement spacing of the grouting pipelines on the end section of the grouting pipeline of the shield body 1 of the joint leading shield, that is, the longitudinal spacing of the grouting holes is equal to the radial arrangement spacing. The transverse spacing represents Figure 3 The distance between adjacent grouting holes in the transverse direction, the longitudinal spacing represents Figure 3 The distance between adjacent rows of grouting holes in the longitudinal direction.

[0089] S15: In order to understand the changes in formation pressure and temperature during the grouting process, 4 monitoring holes are designed to bury temperature sensors 9-1, soil pressure boxes 9-2, and pore water pressure gauges 10. According to experience, 10 pore water pressure gauges 10, 5 temperature sensors 9-1 and 5 soil pressure boxes 9-2 are arranged in each monitoring hole. The Y1 monitoring hole 8-4 simulates the shield body position of the docking section. Three monitoring holes, Y2 monitoring hole 8-3, Y3 monitoring hole 8-2, and Y4 monitoring hole 8-1, are set within the range of 4 rows of grouting holes. The design spacing W between the monitoring hole and the grouting hole considers different values, and the value range of W is (0.5R~1.5R), where R represents the grouting diffusion radius. The pressure and temperature response monitoring at different distances in the horizontal direction is realized through this design distance.

[0090] S16: In each monitoring hole, monitoring sensors are set at multiple distance gradients from the grouting point to obtain multiple sets of corresponding data of monitoring pressure and monitoring distance, and the functional relationship between the two is obtained through analysis, thereby determining the change of pressure during the distance gradient process.

[0091] S17: The soil types around the shield in the docking section are medium-coarse sand, silty sand and silty clay, respectively. Therefore, the in-situ test grouting depth range includes medium-coarse sand, silty sand and silty clay layers to ensure the consistency of the grouting formation.

[0092] for example Figure 1 and Figure 2 Based on the specific setting of m=4, 4 circles of curtain grouting pipelines with a total of 156 are designed for the shield joint section. 3 circles are designed for the joint of the leading shield body 1, and 1 circle is designed for the joint of the trailing shield body 2. The curtain grouting pipelines are arranged in a radiating manner from the inner wall of the shield shell to the surrounding rock of the joint section at 4 angles. The ends of the 13 circles of grouting pipelines for the joint of the leading shield body are on the same cutting plane, and this cutting plane can intercept the 1 circle of grouting pipelines and the shield shell position of the joint of the trailing shield body 2. The specific positions are as follows: Figure 1 and Figure 2 As shown, three rows of grouting pipelines are arranged on the shield body 1 of the leading shield machine, namely, curtain grouting A row grouting pipelines 3, curtain grouting B row grouting pipelines 4 and curtain grouting C row grouting pipelines 5, and one row of grouting pipelines is arranged on the shield body 2 of the trailing shield machine, namely, curtain grouting D row grouting pipelines 6.

[0093] As it is difficult to realize the curtain grouting test simulation of the whole state of the shield docking section in the underground environment with the current technology, simulating the effect of the curtain grouting process on the shield body by surface grouting is the most effective way. The curtain grouting of the docking section adopts the backward grouting process, and the distance between the grouting point and the shield shell is gradual. However, the current surface drilling and grouting technology can only be carried out in a vertical manner, which makes it impossible to simulate the gradual change of distance. Therefore, combined with the position of the pipeline and the shield shell on the end section of the 3-circle grouting pipeline of the shield body 1 of the docking advance shield, 12 grouting pipelines with 3 rows in the annular direction and 4 circles in the radial direction are locally selected to design the distribution form of the in-situ grouting pipeline, and the simulation of the gradual change of distance is realized by setting monitoring sensors at multiple distance gradients from the grouting points. By deploying a large number of sensors and subsequently analyzing the changes in sensor parameters at the distance from the grouting points, the change rules are summarized, and the change curves of the distance and monitoring parameters are drawn to achieve the analysis of the gradual change of distance.

[0094] like Figure 3 As shown, according to the 4 circles of curtain grouting pipelines in the shield docking section, 4 rows are designed, with 3 holes in each row, for a total of 12 vertical grouting holes: A row grouting pipeline 3 is provided with A row grouting holes 7-1: grouting hole Z10, grouting hole Z11 and grouting hole Z12, B row grouting pipeline 4 is provided with B row grouting holes 7-2: grouting hole Z7, grouting hole Z8 and grouting hole Z9, C row grouting pipeline 5 is provided with C row grouting holes 7-3: grouting hole Z4, grouting hole Z5 and grouting hole Z6, D row grouting pipeline 6 is provided with D row grouting holes 7-4: grouting hole Z1, grouting hole Z2 and grouting hole Z3.

[0095] In order to understand the changes in formation pressure and temperature during the grouting process, four monitoring holes are designed to bury temperature sensors 9-1, soil pressure boxes 9-2 and pore water pressure gauges 10: Y1 monitoring hole 8-4, Y2 monitoring hole 8-3, Y3 monitoring hole 8-2, and Y4 monitoring hole 8-1. Among them, Y1 monitoring hole 8-4 simulates the position of the shield body of the docking section, and three monitoring holes, Y2 monitoring hole 8-3, Y3 monitoring hole 8-2, and Y4 monitoring hole 8-1, are set within the range of four rows of grouting holes. The grouting hole range here refers to: the area surrounded by the outer grouting holes. Figure 3 The grouting hole range refers to the area surrounded by grouting hole Z1, grouting hole Z2, grouting hole Z3, grouting hole Z6, grouting hole Z9, grouting hole Z12, grouting hole Z11, grouting hole Z10, grouting hole Z7, and grouting hole Z4. The design spacing W between the monitoring hole and the grouting hole takes into account different values, and the value range of W is 0.5R~1.5R, where R represents the grouting diffusion radius. The pressure and temperature response monitoring at different distances in the horizontal direction is realized through this design distance.

[0096] The soil around the shield at the docking section is medium-coarse sand, fine silt sand and silty clay, so the in-situ test grouting depth range is medium-coarse sand, fine silt sand and silty clay to ensure the consistency of the grouting stratum. Figure 4 shown.

[0097] Furthermore, the monitoring hole drilling and sensor installation in step S2 specifically include the following steps:

[0098] S21: Use mud wall protection to drill monitoring holes for placing buried sensors;

[0099] S22: Tie and fix the pore water pressure gauge 10, the earth pressure box 9-2, and the temperature sensor 9-1 on the steel frame and lower them into the formation grouting area 14;

[0100] S23: The vertical distance gradient of the pore water pressure gauge 10 is Hp, with a value range of 2-3m, and the vertical distance gradient of the earth pressure box 9-2 and the temperature sensor 9-1 is Hw, with a value range of 4-6m, to achieve pressure response monitoring at different depths in the vertical direction;

[0101] Furthermore, the vertical distance gradient of the pore water pressure gauge 10, the vertical distance gradient of the earth pressure box 9-2 and the temperature sensor 9-1 satisfy the following relationship:

[0102] Hp=γ·h

[0103] Hw1=ξ1·h

[0104] Hw2=ξ2·h

[0105] Wherein, Hp represents the vertical distance gradient of the pore water pressure gauge, Hw1 and Hw2 represent the vertical distance gradients of the earth pressure box and the temperature sensor, respectively, h represents the spacing of the slurry outlet holes opened on the hole wall of the sleeve valve pipe, γ represents the vertical distribution coefficient of the pore water pressure gauge, ξ1 and ξ2 represent the vertical distribution coefficients of the earth pressure box and the temperature sensor, respectively.

[0106] S24: After the sensor is lowered, coarse sand and clay balls are used to backfill the gaps in the monitoring hole. Multiple backfilling is used to ensure that the gaps are filled densely. After the formation is stable and dense, the sensor signal value is cleared to zero, which can more clearly show the changes in formation pressure and temperature during the grouting process.

[0107] Furthermore, the processing of the sleeve valve tube 12 in step S3 includes the following steps:

[0108] S31: The sleeve valve tube 12 includes a plurality of sleeve valve sub-tubes, which are connected by connecting sleeves. The sleeve valve sub-tubes are made of seamless steel pipes with an outer diameter of 60 mm and a wall thickness of 3.5 mm, and the connecting sleeves are made of seamless steel pipes with a length of 30 cm, an outer diameter of 76 mm, and a wall thickness of 7 mm.

[0109] S32: Figure 6 As shown, the hole wall of the sleeve valve pipe 12 adopts a cross-shaped symmetrical opening as the slurry outlet hole 13, the hole diameter d is 8 mm, the number of holes in each cross section is 4, and the grouting retreat step distance of the shield docking section is 1000 mm, so the vertical hole spacing h of the hole wall of the sleeve valve pipe 12 is 500 mm.

[0110] Furthermore, in order to achieve the coordinated matching of 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 grouting hole 13 in the shield docking section is the same as the area of ​​the overflow hole during the in-situ test. The back-stepping distance S corresponds to the need to open S / h rows of cross 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 equal area principle, A S =4*π(d / 2) 2 *S / h, therefore, the opening diameter of the pulp outlet hole 13 of the sleeve valve tube 12 satisfies the following relationship:

[0111]

[0112] Wherein, d represents the diameter of the test slurry outlet hole 13, A S represents the area of ​​the curtain grouting outlet hole 13 of the docking section, S represents the step-back distance of the shield docking section grouting, and h represents the spacing of the outlet holes 13 opened on the hole wall of the sleeve valve pipe 12;

[0113] S33: The opening of the sleeve valve tube 12 is sealed by nesting the rubber sleeve 15, and a protective steel wire 16 is welded 2 to 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, causing the rubber sleeve 15 to be misplaced. Finally, wrap the rubber sleeve 15 with an electrical tape to ensure its sealing.

[0114] Preferably, the drilling of the grouting hole and the lowering of the sleeve valve pipe 12 in step S4 include the following steps:

[0115] S41: using mud wall protection to drill grouting holes for placing sleeve valve pipes 12 below;

[0116] 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 20 mm is tied and fixed to the pipe wall of the sleeve valve pipe 12 and lowered into the grouting hole 18. The bottom of the PE pipe 19 is set above the bottom of the sleeve valve pipe 12. p Distance, h p Take the range of 2 to 3m.

[0117] Preferably, the filling of the sleeve shell material 20 in step S5 comprises the following steps:

[0118] S51: The casing material 20 includes water, cement and bentonite, and the ratio of water:cement:bentonite is 2:1:1.

[0119] 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 from the ground along the outer wall of the sleeve valve pipe 12 and the gap between the formation.

[0120] In step S6, the grouting of the sleeve valve tube 12 comprises the following steps:

[0121] S61: Use the skip hole grouting method to perform double liquid grouting pre-reinforcement. Before the formal grouting, double liquid grouting is first performed on the outermost holes (grouting holes Z1, Z3, Z10, and Z12). Combined with the fast setting characteristics of double liquid grout, the phenomenon of grouting on the surface and grouting in the monitoring hole is solved. Double liquid grout ratio method: cement slurry water-cement ratio is 1:1, and cement slurry and water glass mass ratio is 1:1.

[0122] S62: Single hole grouting adopts the backward staged grouting process, that is, grouting is carried out from the bottom of the hole in the grouting area 14, such as Figure 5 As shown, a grouting core tube 11 with a double water bag type grouting plug is designed for fixed-point grouting, and the retreat step S is 1m. After the first grouting section is completed, the grouting core tube is retreated to carry out grouting of the second grouting section, and this cycle is repeated until the single-hole grouting operation is completed.

[0123] S63: The dual control standard of grouting pressure and grouting volume is adopted. Grouting of this hole and this section can be ended when the grouting control pressure reaches the designed test hole grouting pressure or the grouting volume reaches 1.5-2.0 times of the designed grouting volume. Then the drill is withdrawn by 2m, and so on, until the grouting of this hole is ended.

[0124] Furthermore, the designed grouting volume satisfies the following relationship:

[0125] Q=V*n*ɑ*β

[0126] V=πR 2 *H

[0127] Among them, Q represents the designed grouting volume, V represents the volume of the reinforced soil, R represents the grouting diffusion radius, H represents the depth of the grouting section, n represents the void ratio of the reinforced stratum soil, ɑ represents the stratum filling coefficient, which is 0.8, and β represents the slurry loss coefficient, which is 1.1.

[0128] 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 in the protection scope of the present invention.

Claims

1. An in-situ test method based on shield butt curtain grouting, characterized in that: The steps include: S1: Curtain grouting pipelines are set up for the butt-jointed shield body of the leading shield and the butt-jointed shield body of the trailing shield, wherein the curtain grouting pipelines of each circle of the butt-jointed shield body are arranged in a radial shape from the inner wall of the shield shell to the surrounding rock of the butt-jointed section, and the ends of the curtain grouting pipelines of each circle of the butt-jointed shield body are on the same cutting plane, and the curtain grouting pipelines of the trailing shield pass through the cutting plane, and the cutting plane is in contact with the shield shell of the butt-jointed shield body of the trailing shield, and m rows of grouting holes are set up for m circles of curtain grouting pipelines respectively, and multiple monitoring holes are set up at the same time; S2: burying sensors in the monitoring holes, and connecting them to data acquisition devices after the sensors are buried to prepare for the acquisition of formation response parameters during the subsequent grouting process; S3: Use sleeve valve pipe as grouting pipeline for formation grouting; S4: Drill holes according to the designed position of the grouting holes and lower the sleeve valve pipe; S5: After the sleeve valve pipe is lowered, the gap between the outer side of the pipe wall and the formation is filled with casing material; S6: After the shell material has been consolidated to a certain strength, the sleeve valve pipe is grouted backward; S7: Real-time monitoring of sensor data during grouting; S8: After the grouting is completed, the hole is sealed; S9: When the sensor output data remains stable, remove the data acquisition device and complete the test.

2. The in-situ test method based on shield butt curtain grouting according to claim 1 is characterized in that: The shield grouting pipeline of the leading shield is constrained by the grouting diffusion radius: L c ≤R L a ≥[D]-R Among them, L c It indicates the vertical distance between the end point of the innermost pipeline of the shield body grouting of the first shield and the shield body, R indicates the grouting diffusion radius, L a It indicates the vertical distance between the end point of the outermost pipeline of the shield body grouting of the preceding shield and the shield body, and [D] indicates the maximum surrounding rock grouting reinforcement thickness.

3. The in-situ test method based on shield butt curtain grouting according to claim 1 is characterized in that: The shield grouting pipeline of the leading shield is restricted by the width of the lateral surrounding rock grouting reinforcement: U≥[U] Wherein, U represents the distance from the end section of the m-circle curtain grouting pipeline to the butt joint surface, and [U] represents the minimum lateral surrounding rock grouting reinforcement width.

4. The in-situ test method based on shield butt curtain grouting according to claim 1 is characterized in that: The number of grouting lines per circle 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 Indicates the circumferential spacing of the outermost pipelines of curtain grouting, R 盾构 represents the radius of the shield, R represents the grouting diffusion radius, L a It indicates the vertical distance between the outermost pipeline end point of curtain grouting and the shield body, and θ indicates the angle between the adjacent pipeline end points in the same circle on the section of the pipeline end point.

5. The in-situ test method based on shield butt curtain grouting according to claim 1 is characterized in that: The transverse spacing of the grouting holes simulates the circumferential arrangement spacing of the grouting pipelines on the cross-section of the end of the grouting pipelines docking the shield body of the preceding shield machine; the longitudinal spacing of the grouting holes simulates the radial arrangement spacing of the grouting pipelines on the cross-section of the end of the grouting pipelines docking the shield body of the preceding shield machine.

6. The in-situ test method based on shield butt curtain grouting according to claim 1 is characterized in that: One monitoring hole simulates the shield body position of the docking section, and other monitoring holes are set within the grouting hole range. The spacing 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.

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

8. The in-situ test method based on shield butt curtain grouting according to claim 1 is characterized in that: The area of ​​the grouting holes in the shield joint section is the same as the area of ​​the overflow holes during the in-situ test, thereby achieving a coordinated match between the grouting speed during the in-situ test and the grouting speed of the joint section.

9. The in-situ test method based on shield butt curtain grouting according to claim 8 is characterized in that: The step-back distance of grouting in the shield joint section is S, the spacing of the grouting holes opened on the sleeve valve pipe hole wall is h, the sleeve valve pipe wall is opened with S / h rows of cross holes, and 4 overflow holes in a single row. Then the diameter of the sleeve valve pipe grouting hole opening satisfies the following relationship to ensure that the grouting hole area of ​​the shield joint section is the same as the overflow hole area during the in-situ test: Where d is the diameter of the test slurry outlet hole, A S It represents the area of ​​the curtain grouting holes in the docking section, S represents the retreat distance of the grouting in the docking section of the shield, and h represents the spacing between the grouting holes opened on the hole wall of the sleeve valve pipe.

10. The in-situ test method based on shield tunneling butt curtain grouting according to claim 1, characterized in that: The designed grouting volume satisfies the following relationship: Q=V*n*ɑ*β V=πR 2 *H Among them, Q represents the designed grouting volume, V represents the volume of the soil to be reinforced, R represents the grouting diffusion radius, H represents the depth of the grouting section, n represents the void ratio of the reinforced stratum soil, ɑ represents the stratum filling coefficient, and β represents the slurry loss coefficient.

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