An in-situ test method based on shield docking curtain grouting

Abstract

The present invention discloses an in-situ test method based on shield docking curtain grouting. By designing the number of turns and length of the curtain grouting pipeline layout, the slurry injected from each pipeline is fully overlapped. The minimum number of curtain grouting pipelines is used to make the surrounding rock grouting reinforcement range meet the design requirements, fully filling the water system channels in the surrounding rock, providing a stable water-free environment for subsequent excavation, and effectively solving the problems in the prior art such as the lack of theoretical calculation basis, affecting the surrounding rock reinforcement range in the shield docking section, the slurry overlapping quality problem caused by too large pipeline spacing layout, and significantly affecting the reinforcement and water-stop effect on the surrounding rock in the docking section. At the same time, the invention presets sensors by drilling holes within the grouting range to real-time monitor the formation pressure response caused by the slurry pressure and the formation temperature change caused by the slurry hydration heat during the grouting process, providing data support for the selection of grouting parameters in the formation grouting reinforcement project.

Description

Technical Field

[0001] The present invention belongs to the technical field of grouting in geotechnical engineering, and particularly relates to an in-situ test method based on shield docking curtain grouting. Background Technique

[0002] In recent years, tunnel engineering construction has been in full swing, and the process of underground space development has been accelerating continuously. The grouting technology plays a crucial role in the tunnel construction process. Among numerous grouting technologies, the sleeve valve pipe grouting method is widely used in aspects such as foundation reinforcement and water-stop curtain in the tunnel engineering construction due to its high construction flexibility, deep grouting depth, etc., and it can realize multi-point and quantitative grouting in the soil layer. In addition, the sleeve valve pipe grouting method can better control the grouting range and grouting pressure, can realize repeated grouting, and largely avoids the phenomena of slurry gushing and cross-grouting.

[0003] Many scholars have carried out a large number of studies on the sleeve valve pipe grouting reinforcement technology. The literature CN116892210A discloses a sleeve valve pipe grouting device and a grouting method, which have the function of drilling and grouting simultaneously, greatly improving the grouting efficiency; the literature CN217629921U discloses a sleeve valve pipe grouting auxiliary orientation device, which solves the problem of the connection between the grouting device body and the soil; the literature CN114718046A discloses a sleeve valve pipe grouting structure for deep backfill soil layer and its construction method, which is applicable to high-pressure grouting operations, and the sleeve valve pipes are assembled quickly and tightly, facilitating grouting in the deep backfill soil layer; the literature CN112813959A discloses a sleeve valve pipe grouting device and a grouting method based on an elastic membrane, significantly improving the effect of stratum reinforcement and water stop; the literature CN105714764A discloses a construction method for tunnel surface deep-hole sleeve valve pipe grouting, elaborating in detail the technological process of sleeve valve pipe grouting, but the grouting device is difficult to avoid the drawback of slurry gushing at the orifice of the sleeve valve pipe during the grouting process.

[0004] Based on the existing research, although a large number of technical achievements have been disclosed, in terms of design, there is no unified standard for the design method of the curtain grouting pipeline. In terms of grouting construction, the current technology is mostly limited to the improvement of the grouting device and the optimization of the process. The developed devices and processes still cannot completely avoid the risk of slurry gushing from the grouting holes and the ground surface. The research results on the stratum response during the grouting process are relatively few, and there are the following technical difficulties:

[0005] 1. There is no unified standard for the design of the curtain grouting pipeline. How to layout the number of circles of the curtain grouting pipeline and the number of pipelines in each circle is mostly limited to the empirical level, lacking a theoretical calculation basis, thus affecting the surrounding rock reinforcement range of the shield docking section, as well as the slurry intersection quality problem caused by too large a layout distance between pipelines, and then significantly affecting the reinforcement and water-stop effect of the surrounding rock in the docking section, and unable to provide a stable and water-free environment for the subsequent shield excavation.

[0006] 2. The acting force of the slurry pressure on the formation or adjacent structures during the grouting process is not yet clear. There is a possibility that the slurry pressure may damage the adjacent structures during actual grouting construction. There are certain limitations in how to dynamically adjust parameters such as grouting pressure and grouting volume according to the formation pressure response.

[0007] 3. During the grouting process, there is a phenomenon of slurry gushing at the orifice of the sleeve valve pipe and on the ground, resulting in the slurry being unable to be injected into the formation to be reinforced, greatly reducing the reinforcement and water-stop effect.

[0008] 4. When using the single water bag type grout stopper grouting core pipe for grouting conventionally, the grout outlet position cannot be accurately controlled, resulting in uneven grouting reinforcement effect.

[0009] 5. It is difficult to know the situation of the formation temperature rising due to the hydration heat of the slurry after the grouting is completed. Summary of the Invention

[0010] The purpose of the present invention is to address the above problems existing in the prior art, overcome the deficiencies of the prior art, and design an in-situ test method based on shield docking curtain grouting. By optimizing the design of the number of circles and length of the curtain grouting pipeline layout, the surrounding rock grouting reinforcement range meets the design requirements, and the slurries injected from each pipeline are fully intersected to fully fill the water system channels in the surrounding rock, 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 arranging pressure and temperature sensors to monitor the formation pressure response caused by the slurry pressure and the formation temperature change caused by the slurry hydration heat during the grouting process in real time, exploring the growth and dissipation laws of the formation pressure and temperature, and then adjusting the grouting parameters in real time according to the monitoring data to meet the actual engineering requirements.

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

[0012] S1: Set up curtain grouting pipelines for the shield body of the leading shield and the shield body of the trailing shield for docking. Among them, each circle of curtain grouting pipelines of the shield body of the leading shield is arranged radially from the inner wall of the shield shell to the surrounding rock of the docking section. The ends of each circle of curtain grouting pipelines of the shield body of the leading shield are on the same tangent plane. The curtain grouting pipeline of the trailing shield passes through this tangent plane, and this tangent plane is in contact with the shield shell of the shield body of the trailing shield for docking. m rows of grouting holes are respectively set for m circles of curtain grouting pipelines. At the same time, a plurality of monitoring holes are set;

[0013] S2: Bury sensors in the monitoring holes. After the sensors are buried, connect the data acquisition device to prepare for the acquisition of formation response parameters during the subsequent grouting process;

[0014] S3: Use the sleeve valve pipe as the grouting pipeline to carry out formation grouting;

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

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

[0017] S6: After the casing material consolidates and gains strength, backward grouting of the sleeve valve pipe is carried out;

[0018] S7: Monitor the sensor data in real time during the grouting process;

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

[0020] S9: When the data output by the sensor is stable and unchanged, remove the data acquisition device to complete the test.

[0021] Furthermore, the grouting pipeline of the docking shield of the leading shield is restricted by the grouting diffusion radius:

[0022] L c ≤R

[0023] L a ≥[D] - R

[0024] Wherein, L c represents the vertical distance from the end point of the innermost grouting pipeline of the docking shield of the leading shield to the shield body, R represents the grouting diffusion radius, and L a represents the vertical distance from the end point of the outermost grouting pipeline of the docking shield of the leading shield to the shield body, and [D] represents the maximum surrounding rock grouting reinforcement thickness.

[0025] Furthermore, the grouting pipeline of the docking shield of the leading shield is restricted by the lateral surrounding rock grouting reinforcement width:

[0026] U≥[U]

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

[0028] Preferably, the number n of each circle of grouting pipelines is restricted as follows:

[0029] b A ≤2R

[0030] (R 盾构 +L a )×πθ / 180°≤2R

[0031] θ = 360° / n

[0032] Wherein, b A represents the circumferential spacing of the outermost grouting pipeline of the curtain grouting, R 盾构 represents the radius of the shield, and L aIt represents the vertical distance from the end point of the outermost pipeline of the curtain grouting to the shield body, and θ represents the included angle between the end points of adjacent pipelines in the same circle on the cross 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 cross section of the grouting pipelines of the shield body of the advancing shield; the longitudinal spacing of the grouting holes simulates the radial arrangement spacing of the grouting pipelines on the end cross section of the grouting pipelines of the shield body of the advancing shield.

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

[0035] 0.5R ≤ W ≤ 1.5R

[0036] Wherein, R represents the grouting diffusion radius, and W represents the designed spacing between the monitoring hole and the grouting hole.

[0037] Preferably, the sensors in step S2 include a pore water pressure gauge, an earth pressure cell, and a temperature sensor, and satisfy 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 respectively represent the vertical distance gradients of the earth pressure cell and the temperature sensor, h represents the spacing of the slurry outlet holes opened on the wall of the sleeve valve pipe, γ represents the vertical distribution coefficient of the pore water pressure gauge, and ξ1 and ξ2 respectively represent the vertical distribution coefficients of the earth pressure cell and the temperature sensor.

[0042] Furthermore, the area of the slurry outlet holes in the shield docking section is the same as the area of the slurry overflow holes during the in-situ test, so as to achieve the coordinated matching of the grouting speed during the in-situ test and the grouting speed in the docking section.

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

[0044]

[0045] Wherein, d represents the opening diameter of the test slurry outlet holes, A S represents the area of the slurry outlet holes of the curtain grouting in the docking section, S represents the grouting retreating step distance in the shield docking section, and h represents the spacing of the slurry outlet holes opened on the 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] Wherein, Q represents the designed grouting volume, V represents the volume of the soil mass to be reinforced, R represents the grouting diffusion radius, H represents the grouting section depth, n represents the void ratio of the soil mass in the stratum to be reinforced, 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 docking curtain grouting provided by the present invention realizes the complete intersection of the slurries injected from each pipeline by designing the number of turns and length of the curtain grouting pipeline layout, and uses the least number of curtain grouting pipelines to make the surrounding rock grouting reinforcement range meet the design requirements, fully filling the water system channels of the surrounding rock and providing a stable water-free environment for the subsequent excavation.

[0052] (2) The in-situ test method based on shield docking curtain grouting provided by the present invention innovatively presets pressure and temperature sensors by drilling holes in the grouting area to monitor the formation pressure response caused by the slurry pressure and the formation temperature change caused by the slurry hydration heat during the grouting process in real time. Through this monitoring means, the growth and dissipation laws of the formation pressure and temperature during the grouting process are clarified, and the action mechanism of the grouting reinforcement is revealed. It provides data support for the selection of grouting parameters in the formation grouting reinforcement project, and further provides a reference for the analysis of the acting external force on the adjacent structure and the design of the temperature boundary condition in the subsequent actual engineering grouting construction.

[0053] (3) The in-situ test method based on shield docking curtain grouting provided by the present invention summarizes the variation law of the formation pressure along the 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 at different depths and different strata in the vertical direction.

[0054] (4) The in-situ test method based on shield docking curtain grouting provided by the present invention makes the slurry inject into the formation from the slurry overflow hole between the two water stop bags by designing the grouting core pipe of the double water bag type stop grout plug. After the grouting per meter is completed, the grouting core pipe of the double water bag type stop grout plug is retracted 1 m, and the equal slurry overflow holes are always located between the two water stop bags during the overall retraction process, accurately controlling the slurry outlet position and the slurry outlet speed, and realizing the uniform reinforcement of the formation.

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

[0056] (6) The in-situ test method based on shield docking curtain grouting provided by the present invention adopts the method of grouting in alternate holes for double-fluid grouting pre-reinforcement through step S61, and solves the problems of surface slurry gushing and slurry channeling in the monitoring holes. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0060] Figure 4 is the sectional view of the grouting holes and monitoring hole positions of the present invention;

[0061] Figure 5 is the grouting schematic diagram of the double-water-bag grouting plug type grouting core pipe of the present invention;

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

[0063] In the figure: 1 - shield body of the docking advancing shield, 2 - shield body of the docking trailing 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 - earth pressure cell, 10 - pore water pressure gauge, 11 - grouting core pipe, 12 - sleeve valve pipe, 13 - slurry outlet hole, 14 - grouting area, 15 - rubber sleeve, 16 - protection wire, 17 - water injection hole, 18 - grouting hole, 19 - PE pipe, 20 - casing material. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

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

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

[0067] S2: Drill surface holes according to the designed positions of the monitoring holes for burying sensors. After the sensors are buried, connect the data acquisition device to prepare for collecting formation response parameters during the subsequent grouting process;

[0068] S3: Process the sleeve valve pipe 12 with seamless steel pipes and use the processed sleeve valve pipe 12 as the grouting pipeline to grout the formation;

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

[0070] S5: After the sleeve valve pipe 12 is lowered, use the casing material 20 to fill the gap between the outer wall of the pipe and the formation;

[0071] S6: After the casing material 20 consolidates and gains strength, lower the double-water-bag grouting plug core pipe. Fix the grouting core pipe by injecting water and pressurizing through the water injection hole 17 and prevent the slurry from flowing up along the sleeve valve pipe, and perform backward grouting of the sleeve valve pipe 12;

[0072] S7: Real-time monitor the formation pressure and temperature response during the grouting process through the data output by the sensors;

[0073] S8: After the grouting is completed, perform hole sealing treatment;

[0074] S9: When the data output by the sensors is stable, remove the data acquisition device to complete the test.

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

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

[0077] S12: The number of circles m of the curtain grouting pipeline 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 from the end point of the innermost curtain grouting pipeline to the shield body c ≤R, so that there is no slurry blank area outside the shield body in the docking section, and the surrounding rock can be completely reinforced by the slurry.

[0079] (2) The vertical distance L from the end point of the outermost curtain grouting pipeline to the shield body a≥ [D] - R, so as to ensure that the surrounding rock reinforcement thickness meets the requirements of bearing and water stopping during subsequent excavation.

[0080] (3) The distance U from the end section of the m - ring curtain grouting pipeline to the docking surface ≥ [U], so as to ensure the width of the surrounding rock grouting reinforcement in the docking section to block the lateral incoming water.

[0081] [D] represents the maximum surrounding rock grouting reinforcement thickness, and the value range is 3 - 5m.

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

[0083] S13: The number n of each ring of curtain grouting pipelines is mainly affected by the circumferential spacing b of the outermost ring of pipelines in the curtain grouting A , and 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] Among them: b A represents the circumferential spacing of the outermost pipelines in the curtain grouting, R 盾构 represents the radius of the shield, and θ represents the included angle between the end points of adjacent pipelines in the same circle on the end section of the pipeline.

[0088] S14: Design m rows of grouting holes according to the m - ring curtain grouting pipelines in the shield docking section. Each row of grouting holes is designed with n'. In order to make the in - situ test more in line with the grouting effect of the curtain grouting group holes in the docking section and meet certain economy, design n' = 3. The transverse spacing of the grouting holes simulates the circumferential arrangement spacing of the grouting pipelines on the end section of the shield body 1 of the docking - first shield, that is, the transverse 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 pipelines on the end section of the shield body 1 of the docking - first 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 in Figure 3 and the longitudinal spacing represents

[0089] S15: To monitor the changes in formation pressure and temperature during the grouting process, 4 monitoring holes are designed for installing temperature sensors 9-1, earth pressure cells 9-2, and pore water pressure gauges 10. According to experience, 10 pore water pressure gauges 10, 5 temperature sensors 9-1, and 5 earth pressure cells 9-2 are arranged in each monitoring hole. The Y1 monitoring hole 8-4 simulates the position of the shield body in the docking section. Three monitoring holes, namely the 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. Different values are considered for the designed spacing W between the monitoring holes and the grouting holes. The value range of W is (0.5R~1.5R), where R represents the grouting diffusion radius. Through this designed distance, the pressure and temperature response monitoring at different horizontal distances is achieved.

[0090] S16: In each monitoring hole, a method of setting monitoring sensors at multiple distance gradients from the grouting point is adopted to obtain multiple sets of corresponding data of monitoring pressure and monitoring distance. By analyzing, the functional relationship between the two is obtained, and then the change of pressure during the distance gradual change is determined.

[0091] S17: The surrounding soils of the shield in the docking section are medium coarse sand, fine silt, and silty clay respectively. Therefore, the in-situ test grouting depth ranges are medium coarse sand, fine silt, and silty clay strata respectively to ensure the consistency of the grouting formation.

[0092] For example Figure 1 and Figure 2 are based on the specific setting of m = 4. In the shield docking section, a total of 156 curtain grouting pipelines are designed in 4 circles. For the leading shield body 1 of the docking, 3 circles are designed, and for the trailing shield body 2 of the docking, 1 circle is designed. The curtain grouting pipelines are radially arranged from the inner wall of the shield shell to the surrounding rock of the docking section at 4 angles. The ends of the 3-circle grouting pipelines of the leading shield body 1 of the docking are on the same section plane, and this section plane can intercept 1 circle of grouting pipelines and the shield shell position of the trailing shield body 2 of the docking. The specific positions are as Figure 1 and Figure 2 shown. 3 rows of grouting pipelines are set on the leading shield body 1 of the docking, namely the curtain grouting A row of grouting pipelines 3, the curtain grouting B row of grouting pipelines 4, and the curtain grouting C row of grouting pipelines 5. 1 row of grouting pipelines is set on the trailing shield body 2 of the docking, which is the curtain grouting D row of grouting pipelines 6.

[0093] Since it is difficult to simulate the curtain grouting test of the full state of the shield docking section underground with current technologies, it is the most effective way to simulate the effect of curtain grouting on the shield body through surface grouting. The backstepping grouting process is adopted for the curtain grouting of the docking section, and the distance between the grouting points and the shield shell changes gradually. However, the current surface drilling and grouting technologies can only be carried out vertically, resulting in the inability to simulate the gradual change of distance. Therefore, considering the position of the pipelines and the shield shell on the end section of the three-ring grouting pipelines of the shield body 1 of the docking first shield, a total of 12 grouting pipelines are locally selected in 3 circumferential rows and 4 radial circles to design the in-situ grouting pipeline distribution form, and the gradual change of distance is simulated by setting monitoring sensors at multiple distance gradients from the grouting points. By arranging a large number of sensors and analyzing the change of sensor parameters at different distances from the grouting points, the change law is summarized, and the change curve of distance and monitoring parameters is drawn to achieve the analysis of the gradual change of distance.

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

[0095] To master the change of formation pressure and temperature during the grouting process, 4 monitoring holes are designed for burying temperature sensors 9-1, earth pressure cells 9-2, and pore water pressure gauges 10: Y1 monitoring hole 8-4, Y2 monitoring hole 8-3, Y3 monitoring hole 8-2, Y4 monitoring hole 8-1. Among them, the Y1 monitoring hole 8-4 simulates the position of the shield body in the docking section, and three monitoring holes, namely Y2 monitoring hole 8-3, Y3 monitoring hole 8-2, and Y4 monitoring hole 8-1, are set within the range of the 4 rows of grouting holes. Here, the range of the grouting holes refers to the area surrounded by the outer grouting holes. As Figure 3 shown, the range of the grouting holes refers to the area surrounded by grouting holes Z1, Z2, Z3, Z6, Z9, Z12, Z11, Z10, Z7, and Z4. Different values are considered for the designed spacing W between the monitoring holes and the grouting holes, and the value range of W is 0.5R to 1.5R, where R represents the grouting diffusion radius. Through this designed distance, the pressure and temperature response monitoring at different distances in the horizontal direction is achieved.

[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: As shown Figure 6 in, the wall of the 12 holes of the sleeve valve pipe adopts a cross-shaped symmetric hole-opening form as the grout outlet holes 13, the hole-opening diameter d is 8 mm, the number of holes opened in each cross-section is 4, and the backward step distance of grouting in the shield docking section is 1000 mm. Therefore, the vertical hole-opening spacing h of the wall of the 12 holes of the sleeve valve pipe 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 in the docking section, it is necessary to ensure that the area of the grout outlet holes 13 in the shield docking section is the same as the area of the slurry overflow holes during the in-situ test. The corresponding backward step distance S requires 2 to open S / h rows of cross-shaped holes on the wall of the 12 sleeve valve pipes, with 4 slurry overflow holes in a single row, and the total area of the single-row slurry overflow holes is 4*π(d / 2) S According to the equal-area principle, A 2 = 4*π(d / 2)

[0111]

[0112] *S / h. Therefore, the hole-opening diameter of the grout outlet holes 13 of the 12 sleeve valve pipes satisfies the following relationship: S where d represents the hole-opening diameter of the test grout outlet holes 13, A

[0113] represents the area of the grout outlet holes 13 of the curtain grouting in the docking section, S represents the backward step distance of grouting in the shield docking section, and h represents the spacing of the grout outlet holes 13 opened on the wall of the 12 sleeve valve pipes;

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

[0115] S41: Adopt the form of slurry-supported wall to drill the grouting holes for lowering the 12 sleeve valve pipes;

[0116] S42: After the grouting holes 18 are formed, lower the 12 sleeve valve pipes. To facilitate the injection of the casing material 20, tie and fix a PE pipe 19 with an outer diameter of 20 mm to the wall of the 12 sleeve valve pipes and lower them into the grouting holes 18 together. The bottom of the PE pipe 19 is set at a distance of h p above the bottom of the 12 sleeve valve pipes, and h p is taken in the range of 2 - 3 m.

[0117] Preferably, in step S5, the filling of the casing material 20 includes the following steps:

[0118] S51: The configuration materials of the casing material 20 include 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 through the PE pipe 19 to the bottom of the grouting hole 18, so that the casing material 20 completely replaces the mud in the hole from bottom to top until the casing material 20 overflows the ground along the outer wall of the sleeve valve pipe 12 and the formation gap.

[0120] The grouting of the sleeve valve pipe 12 in step S6 includes the following steps:

[0121] S61: Adopt the method of grouting in a skipping pattern for double-fluid grouting pre-reinforcement. Before formal grouting, first perform double-fluid grouting on the outermost hole positions (grouting holes Z1, Z3, Z10, Z12), and combine the characteristics of the fast setting of the double-fluid grout to solve the problems of surface grout overflow and grout leakage in the monitoring holes. The mixing ratio of the double-fluid grout: the water-cement ratio of the cement slurry is 1:1, and the mass ratio of the cement slurry to the water glass is 1:1.

[0122] S62: The single-hole grouting adopts the backward segmented grouting process, that is, grouting is carried out from the bottom of the hole in the grouting area 14. As Figure 5 shown, design a grouting core pipe 11 with a double water bag type grout stopper for fixed-point grouting. The backward step distance S is 1m. After grouting the first grouting section, retreat the grouting core pipe and perform grouting on the second grouting section, and so on until the single-hole grouting operation is completed.

[0123] S63: Adopt a double control standard combining grouting pressure and grouting volume. When the grouting control pressure reaches the grouting pressure of the designed test hole or the grouting volume reaches 1.5 - 2.0 times of the designed grouting volume, the grouting of this hole and this section can be ended. Then retreat the drill 2m, and so on until the grouting of this hole is completed.

[0124] Further, 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 soil mass to be reinforced, R represents the grouting diffusion radius, H represents the grouting section depth, n represents the porosity of the soil mass in the formation to be reinforced, ɑ represents the formation filling coefficient, with a value of 0.8, and β represents the slurry loss coefficient, with a value of 1.1.

[0128] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall 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 is stable, the data acquisition device is removed and the test is completed; 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.

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 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.

5. 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.

6. 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.

7. 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.

8. The in-situ test method based on shield butt curtain grouting according to claim 7 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.

9. The in-situ test method based on shield butt curtain grouting according to claim 1 is 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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