A tunnel deformation control method of passive zone reinforcement combined with bag-type grouting

Abstract

The application is a tunnel deformation control method of passive zone reinforcement combined with capsule grouting, comprising the following steps: according to the excavation range of the foundation pit, the foundation pit support structure is arranged; the soil body is reinforced along the longitudinal direction of the tunnel near the tunnel side inside the foundation pit support structure; the gap between the foundation pit support structure and the reinforced area is filled and reinforced by using the pressure grouting method; the drilling construction is carried out along the longitudinal direction of the tunnel in the pressure grouting body inside the foundation pit support structure; the capsule grouting device is arranged in the drilling; the monitoring equipment is arranged in the tunnel; the foundation pit excavation and the inner support construction operation are carried out, the deformation of the tunnel is monitored in real time, and the corresponding convergence deformation value is calculated; when the deformation is close to the warning value, the capsule grouting device is grouted by the monitoring equipment. The application effectively solves the problem that the traditional grouting technology has an impact on the deformation of the foundation pit, simultaneously realizes the real-time control technology of the deformation of the foundation pit and the tunnel in the foundation pit excavation process, and guarantees the normal working state of the tunnel.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, and in particular to a method for controlling tunnel deformation by combining passive zone reinforcement with bladder grouting. Background Technology

[0002] Foundation pit engineering is an important means of urban development and underground space development. With the continuous advancement of urbanization, large-area deep foundation pits are becoming increasingly common. Foundation pit construction causes deformation of the retaining structure and surrounding soil layers, thereby affecting buildings and structures around the foundation pit. With the construction and commissioning of numerous subway tunnels, foundation pit construction around these tunnels is inevitable. To ensure the structural and operational safety of subway tunnels, deformation control standards have become increasingly stringent, shifting from centimeter-level control requirements to millimeter-level requirements. Therefore, control measures for tunnel deformation caused by foundation pit construction should be characterized by precise control.

[0003] Currently, there are two main methods for controlling the deformation of adjacent tunnels caused by foundation pit excavation:

[0004] 1. Passive control methods, namely, controlling deformation by increasing the stiffness of the foundation pit soil and support structure. Traditional passive control technologies include strengthening support stiffness, the optimized excavation method involved in patent application "Construction Method for Foundation Pit Groups Near Operating Subways CN115182354A", and the soil reinforcement and installation of isolation piles involved in patent "A Foundation Pit Support Structure Near Natural Foundation Buildings CN218713081U". While these passive control technologies can effectively control tunnel deformation caused by foundation pit excavation, they require prior determination before excavation and cannot achieve real-time control during excavation. Furthermore, traditional passive control technologies increase project costs and construction time; and they struggle to meet the millimeter-level deformation control requirements of subway tunnels.

[0005] 2. Active control methods, namely feedback control methods that restore the deformation of the protected object in real time based on its deformation state. Patent applications such as "A shield tunneling isolation pile structure and construction method based on servo axial force compensation CN115710938A", "A servo steel-supported foundation pit model test device CN115897680A", and "A deformation-targeted control method suitable for adjacent foundation pit construction CN115681224A" all propose servo active control technology for steel support axial force. Its essence is to control the deformation of the retaining structure through the reaction force of the steel support, thereby achieving deformation control of adjacent buildings and structures. However, for large-area irregular foundation pits, steel support servo control technology is no longer applicable. Active control technology for sleeve raft grouting is widely used in engineering and can effectively control tunnel deformation; however, sleeve raft grouting suffers from problems such as splitting, seepage, and grout leakage, resulting in very low grouting efficiency. The patent "A Multi-Point Combined Grouting System for Controlling Displacement CN218757413U" proposes a bladder-type grouting control technology. Essentially, this technology uses borehole grouting to achieve lateral compression of the surrounding soil, thereby controlling tunnel deformation. However, when the tunnel is very close to the foundation pit, the bladder-type grouting system located between the tunnel and the pit will severely affect the pit's deformation.

[0006] Therefore, there is an urgent need to develop a tunnel deformation control technology that can effectively control pit deformation, while being efficient, economical, safe, and proactive in real time, for tunnel construction projects with ultra-close proximity to foundation pits during service life. Summary of the Invention

[0007] This invention aims to address the shortcomings of existing technologies by providing a tunnel deformation control method that combines passive zone reinforcement with bladder grouting. This method is applicable to tunnel construction projects involving ultra-close contact pits during service life. It allows for real-time active control based on actual site conditions, enabling bidirectional control of pit and tunnel deformation. It is flexible in operation and has a wide range of applications.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a method for controlling tunnel deformation by passive zone reinforcement combined with bladder grouting, comprising the following steps:

[0009] Step 1: Based on the excavation area of ​​the foundation pit, construct the foundation pit retaining structure;

[0010] Step 2: On the inner side of the foundation pit retaining structure, close to the tunnel side, the soil is reinforced along the longitudinal direction of the tunnel, i.e., the reinforcement zone;

[0011] Step 3: Fill and reinforce the gap between the foundation pit retaining structure and the reinforcement zone using compaction grouting. The filling material is compaction grout, and the bottom of the compaction grout is flush with the bottom of the reinforcement zone.

[0012] Step 4: Drill holes along the longitudinal direction of the tunnel within the compaction grouting body inside the foundation pit retaining structure;

[0013] Step 5: Install a bladder-type grouting device inside the borehole; the bladder-type grouting device includes a bladder and a grouting rod. The top and bottom of the bladder are equipped with buckles. The grouting rod is inserted into the bladder and fixed by the buckles. The grouting rod has several grouting holes from top to bottom, and the grouting holes are equipped with one-way valves; the bladder is a cylindrical structure with a diameter of 50cm and a length of 8m. It is installed close to the inner side of the foundation pit retaining structure. The length of the bladder is the same as the length from the bottom of the foundation pit to the bottom of the reinforced area, and the bladders are arranged horizontally along the longitudinal direction of the tunnel at a spacing of 1-2m.

[0014] Grout is injected into the grouting bag through a grouting rod. As the amount of grout injected increases, the volume of the grouting bag continues to increase, thereby squeezing the surrounding soil.

[0015] Step 6: Deploy monitoring equipment inside the tunnel;

[0016] Step 7: Carry out the foundation pit excavation and internal support construction, monitor the tunnel deformation in real time, and calculate the corresponding convergence deformation value;

[0017] Step 8: When the monitoring equipment records that the deformation is close to the warning value, grouting is performed on the bladder-type grouting device.

[0018] Specifically, the reinforcement requirements for the reinforced area in step 2 are as follows: a three-axis soil mixing pile machine is used for full-area reinforcement of the skirt on the passive side of the foundation pit; according to the design requirements, the reinforcement depth range of the soil layer is determined and divided into upper and lower parts. The upper part consists of the soil from the ground surface to the bottom of the innermost support, and this part of the soil is reinforced using a three-axis cement-soil mixing pile machine with a cement content of 10%; the lower part consists of the soil from the bottom of the innermost support to the bottom of the reinforced area, and this part of the soil is reinforced using a three-axis cement-soil mixing pile machine with a cement content of 20%.

[0019] Specifically, the grout used for compaction grouting in step 3 uses cement with a water-cement ratio of 0.55.

[0020] Specifically, the drilling method in step 4 is as follows: Determine the drilling location and depth according to the design requirements; use a drilling machine to drill the hole with a diameter of 80-100mm; use mud slurry to protect the wall during the drilling process; and lift the drill after the drilling machine reaches the specified depth.

[0021] Specifically, the monitoring equipment in step 6 is a displacement meter or total station, which is placed on the side of the tunnel to monitor tunnel deformation in real time.

[0022] Specifically, the method for calculating the convergence deformation value in step 7 is as follows:

[0023] δ=δ L +δ R

[0024] In the formula: δ is the convergent deformation value, δ L The displacement value of monitoring device 6 on the left, δ R The displacement value of monitoring device 6 on the right is defined as outward deformation.

[0025] Specifically, in step 8, the warning value is 70% of the allowable deformation value of the tunnel; grouting is carried out simultaneously by the bladder-type grouting device every 6-8m; grouting is stopped when the real-time monitored deformation value reaches the warning value of 60%.

[0026] Specifically, the grouting bags corresponding to the grouting operation in step 8 need to be determined based on the real-time monitoring results of the tunnel along the longitudinal direction; grouting should be carried out within the range of the tunnel deformation peak along the longitudinal direction; the spacing between grouting operations of the bags within the same peak range should be maintained at 6-8m.

[0027] The beneficial effects of this invention are:

[0028] 1. The technical solution adopted in this invention mainly selects the passive side soil reinforcement combined with the active control method of grouting, which overcomes the shortcomings of traditional passive control technology in that it cannot achieve real-time control and has low control efficiency during construction.

[0029] 2. This invention uses bladder-type grouting technology, which can overcome the shortcomings of traditional sleeve raft grouting such as grout leakage, improve grouting efficiency, and determine the fixed-point grouting range based on real-time monitoring data, thereby improving the accuracy of grouting.

[0030] 3. The passive side reinforcement zone in this invention provides greater lateral earth pressure to the foundation pit retaining structure, enhances the embedment effect of the retaining structure, reduces foundation pit deformation, and thus weakens the impact of foundation pit excavation on adjacent tunnels.

[0031] 4. After the reinforced area in this invention is formed, it has greater rigidity and strength than the surrounding soil, thus providing a certain degree of obstruction for the bladder grouting and improving the efficiency of bladder grouting.

[0032] 5. The bag in this invention controls the deformation of the foundation pit retaining structure by compressing it, thereby reducing the impact of foundation pit excavation on tunnel deformation and ultimately achieving control over tunnel deformation.

[0033] 6. The reinforcement zone and the grouting body in this invention are located on the passive side of the foundation pit, which overcomes the negative impact of traditional grouting technology on the foundation pit and can achieve simultaneous control of the deformation of the foundation pit and tunnel. Attached Figure Description

[0034] Figure 1 This is a cross-sectional schematic diagram of the present invention;

[0035] Figure 2This is a top view of the present invention;

[0036] Figure 3 This is a schematic diagram of the bladder-type grouting structure of the present invention;

[0037] In the diagram: 1-Internal support; 2-Foundation pit retaining structure; 3-Tunnel; 4-Reinforced area; 5-Bag-type grouting device; 6-Monitoring equipment; 7-Compacted grouting body; 8-Bag; 9-One-way valve; 10-Grouting hole; 11-Snap fastener; 12-Grouting rod;

[0038] The following will describe in detail, with reference to the accompanying drawings, embodiments of the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments:

[0040] like Figures 1-3 As shown, a method for controlling tunnel deformation through passive zone reinforcement combined with bladder grouting includes the following steps:

[0041] Step 1: Based on the excavation area of ​​the foundation pit, install the foundation pit retaining structure 2.

[0042] Step 2: On the inner side of the foundation pit retaining structure 2, close to the tunnel 3, soil reinforcement is carried out along the longitudinal direction of the tunnel 3, i.e., reinforcement zone 4; the reinforcement requirements for reinforcement zone 4 are as follows: a three-axis mixing pile machine is used to fully reinforce the skirt of the passive side of the foundation pit; according to the design requirements, the reinforcement depth range of the soil layer is determined and divided into upper and lower parts. The upper part consists of the soil from the ground surface to the bottom of the innermost support 1, and this part of the soil is reinforced by a three-axis cement-soil mixing pile machine with a cement content of 10%; the lower part consists of the soil from the bottom of the innermost support 1 to the bottom of reinforcement zone 4, and this part of the soil is reinforced by a three-axis cement-soil mixing pile machine with a cement content of 20%. The bottom of reinforcement zone 4 is located below the bottom of the foundation pit.

[0043] Step 3: The gap between the foundation pit retaining structure 2 and the reinforcement zone 4 is filled and reinforced by compaction grouting. The filling material is compaction grouting body 7, and the bottom of compaction grouting body 7 is flush with the bottom of reinforcement zone 4. The grout used for compaction grouting is cement with a water-cement ratio of 0.55.

[0044] Step 4: Drilling is carried out along the longitudinal direction of tunnel 3 within the compacted grouting body 7 inside the foundation pit retaining structure 2; the drilling location and depth are determined according to the design requirements; a drilling machine is used for drilling, with a hole diameter of 80-100mm. Mud slurry is used for wall protection during the drilling process, and the drill is lifted after the drilling machine reaches the specified depth.

[0045] Step 5: Install a bladder-type grouting device 5 inside the borehole; the bladder-type grouting device 5 includes a bladder 8 and a grouting rod 12. The top and bottom of the bladder 8 are provided with buckles 11. The grouting rod 12 is inserted into the bladder 8 and connected and fixed by the buckles 11. Several grouting holes 10 are provided on the grouting rod 12 from top to bottom. One-way valves 9 are provided on the grouting holes 10; the bladder 8 is a cylindrical structure made of high-strength and high-elasticity rubber, with a diameter of 50cm and a length of 8m. It is set close to the inner side of the foundation pit retaining structure 2. The length of the bladder 8 is the same as the length from the bottom of the foundation pit to the bottom of the reinforcement area 4, and the horizontal spacing along the longitudinal direction of the tunnel 3 is 1-2m; the diameter of the grouting holes 10 is 30mm, and the spacing of the grouting holes 10 along the burial depth is 100mm. The buckles 11 are made of steel round blocks with a diameter of 70mm and a thickness of 40mm. To prevent the grout from flowing back into the rod, one-way valves 9 are installed at the positions of the grouting holes 10;

[0046] Grout is injected into the bladder 8 through the grouting rod 12. As the amount of grout injected increases, the volume of the bladder 8 continues to increase, thereby squeezing the surrounding soil.

[0047] Step 6: Install monitoring equipment 6 inside tunnel 3; the monitoring equipment 6 adopts displacement gauge or total station and is arranged on the side waist of tunnel 3 to monitor the deformation of tunnel 3 in real time. In order to ensure the continuity of monitoring data, it is arranged at intervals of five times the width of the tunnel segments along the longitudinal direction of tunnel 3.

[0048] Step 7: Carry out the foundation pit excavation and internal support 1 construction work, and monitor the deformation of tunnel 3 in real time, and calculate the corresponding convergence deformation value; the calculation method of the convergence deformation value is as follows:

[0049] δ=δ L +δ R

[0050] In the formula: δ is the convergent deformation value, δ L The displacement value of monitoring device 6 on the left, δ R The displacement value of monitoring device 6 on the right is defined as outward deformation.

[0051] Step 8: When the deformation recorded by the monitoring device 6 approaches the warning value, grouting is performed on the bladder-type grouting device 5;

[0052] The warning value is 70% of the allowable deformation value of Tunnel 3; grouting is carried out simultaneously by the 5-bladder grouting device every 6-8m; grouting is stopped when the real-time monitored deformation value reaches 60% of the warning value; the grout is a mixture of cement and water glass, and the specific configuration parameters need to be determined based on the test and the actual situation.

[0053] The grouting bag 8 corresponding to the grouting operation needs to be determined based on the real-time monitoring results of tunnel 3 along the longitudinal direction; grouting should be carried out within the range of peak deformation along the longitudinal direction of tunnel 3; the grouting operation spacing of the bag 8 within the same peak range should be maintained at 6-8m.

[0054] During the construction of the foundation pit, grouting deformation can be controlled by the principle of small grouting volume and multiple grouting, and the specific grouting plan should be determined according to the actual project conditions.

[0055] The technical solution adopted in this invention mainly selects a passive lateral soil reinforcement combined with bladder grouting active control method, overcoming the shortcomings of traditional passive control technology, such as the inability to achieve real-time control and low control efficiency during construction. The use of bladder grouting technology can overcome the shortcomings of traditional sleeve raft grouting, such as grout leakage, improving grouting efficiency. Furthermore, determining the fixed-point grouting range based on real-time monitoring data can improve grouting accuracy. In this invention, the passive lateral reinforcement zone 4 provides greater lateral earth pressure to the foundation pit retaining structure 2, enhancing the embedment effect of the foundation pit retaining structure 2, reducing foundation pit deformation, and thus reducing the impact of foundation pit excavation on the foundation pit. The influence of the proximity to tunnel 3; and after the reinforcement zone 4 is formed, compared with the surrounding soil, it has greater rigidity and strength, thus it has a certain shielding effect on the bladder grouting, thereby improving the efficiency of bladder grouting; the bladder 8 in this invention controls the deformation of the foundation pit retaining structure 2 by squeezing the foundation pit retaining structure 2, reducing the impact of foundation pit excavation on the deformation of tunnel 3, thereby achieving the final control of the deformation of tunnel 3; the reinforcement zone 4 and the bladder grouting body are located on the passive side of the foundation pit, overcoming the negative impact of traditional bladder grouting technology on the foundation pit, and can achieve simultaneous control of the deformation of the foundation pit and tunnel 3.

[0056] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0057] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0058] The present invention has been described above by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or direct application to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for controlling tunnel deformation by passive zone reinforcement combined with bladder grouting, characterized in that, Includes the following steps: Step 1: Based on the excavation area of ​​the foundation pit, install the foundation pit retaining structure (2); Step 2: On the inner side of the foundation pit retaining structure (2) near the tunnel (3), the soil is reinforced along the longitudinal direction of the tunnel (3), i.e., the reinforcement zone (4); Step 3: The gap between the foundation pit retaining structure (2) and the reinforcement zone (4) is filled and reinforced by compaction grouting. The filling material is compaction grout (7), and the bottom of the compaction grout (7) is flush with the bottom of the reinforcement zone (4). Step 4: Drilling is carried out longitudinally along the tunnel (3) within the compacted grouting body (7) inside the foundation pit retaining structure (2); Step 5: Install a bladder-type grouting device (5) in the borehole; the bladder-type grouting device (5) includes a bladder (8) and a grouting rod (12). The top and bottom of the bladder (8) are provided with buckles (11). The grouting rod (12) is inserted into the bladder (8) and connected and fixed by the buckles (11). Several grouting holes (10) are provided on the grouting rod (12) from top to bottom. One-way valves (9) are provided on the grouting holes (10). The bladder (8) is a cylindrical structure with a diameter of 50cm and a length of 8m. It is set close to the inner side of the foundation pit retaining structure (2). The length of the bladder (8) is the same as the length from the bottom of the foundation pit to the bottom of the reinforcement area (4). The bladders are arranged horizontally along the longitudinal direction of the tunnel (3) with a spacing of 1-2m. Grout is injected into the bag (8) through the grouting rod (12). As the amount of grout increases, the volume of the bag (8) continues to increase, thereby squeezing the surrounding soil. Step 6: Install monitoring equipment (6) inside the tunnel (3); Step 7: Carry out the foundation pit excavation and internal support (1) construction operations, monitor the deformation of the tunnel (3) in real time, and calculate the corresponding convergence deformation value; Step 8: When the monitoring equipment (6) records that the deformation is close to the warning value, grouting is performed on the bladder grouting device (5).

2. The tunnel deformation control method based on passive zone reinforcement combined with bladder grouting according to claim 1, characterized in that, The reinforcement requirements for the reinforcement zone (4) in step 2 are as follows: the skirt of the passive side of the foundation pit is reinforced with a three-axis mixing pile machine; the reinforcement depth range of the soil layer is determined according to the design requirements and divided into upper and lower parts. The upper part consists of the soil between the ground surface and the bottom of the inner support (1), and this part of the soil is reinforced with a three-axis cement-soil mixing pile machine with a cement content of 10%; the lower part consists of the soil between the bottom of the inner support (1) and the bottom of the reinforcement zone (4), and this part of the soil is reinforced with a three-axis cement-soil mixing pile machine with a cement content of 20%.

3. The tunnel deformation control method based on passive zone reinforcement combined with bladder grouting according to claim 1, characterized in that, In step 3, the grout used for compaction grouting is cement with a water-cement ratio of 0.

55.

4. The tunnel deformation control method based on passive zone reinforcement combined with bladder grouting according to claim 1, characterized in that, The drilling method in step 4 is as follows: Determine the drilling location and depth according to the design requirements; use a drilling machine to drill the hole with a diameter of 80-100mm; use mud slurry to protect the wall during the drilling process; and lift the drill after the drilling machine reaches the specified depth.

5. The tunnel deformation control method based on passive zone reinforcement combined with bladder grouting according to claim 1, characterized in that, The monitoring equipment (6) in step 6 uses a displacement meter or a total station and is placed on the side of the tunnel (3) to monitor the deformation of the tunnel (3) in real time.

6. The tunnel deformation control method of passive zone reinforcement combined with bladder grouting according to claim 5, characterized in that, The method for calculating the convergence deformation value in step 7 is as follows: d=d L +d R In the formula: δ is the convergent deformation value, δ L The displacement value of the monitoring device (6) on the left, δ R The displacement value of the monitoring device (6) on the right is defined as outward deformation.

7. The tunnel deformation control method based on passive zone reinforcement combined with bladder grouting according to claim 6, characterized in that, In step 8, the warning value is 70% of the allowable deformation value of the tunnel (3); the grouting device (5) is used for simultaneous grouting every 6-8m interval; grouting is stopped when the real-time monitored deformation value reaches the warning value of 60%.

8. The tunnel deformation control method of passive zone reinforcement combined with bladder grouting according to claim 7, characterized in that, The grouting bag (8) corresponding to the grouting operation in step 8 needs to be determined based on the real-time monitoring results of the tunnel (3) along the longitudinal direction; grouting is carried out within the range of the longitudinal deformation peak of the tunnel (3); the grouting operation spacing of the grout bags (8) within the same peak range is kept at 6-8m.

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