A grouting method for simultaneously recovering tunnel settlement and horizontal deformation

Abstract

The application discloses a grouting method for simultaneously recovering tunnel settlement and horizontal deformation, and steps are as follows: positions and grouting amounts of vertical grouting and oblique multi-point grouting are calculated through numerical simulation software, a vertical grouting hole and a plurality of oblique grouting holes are respectively arranged at corresponding positions of each ring segment; a first grouting device and a second grouting device are prepared; the second grouting device is inserted into the vertical grouting hole, and the first grouting device is respectively inserted into the oblique grouting holes; a foundation pit is excavated in the inner side of the diaphragm wall, tunnel monitoring equipment is observed, if displacement and deformation of a ring segment occur, grouting is carried out into grouting pipes in the vertical grouting hole and the oblique grouting holes at the corresponding positions of the ring segment; after grout solidification, a vertical grouting body and a plurality of point grouting bodies are formed, the monitoring equipment is continuously observed during the grouting process, and when the tunnel horizontal displacement, vertical displacement and ellipticity are recovered to set values, the grouting is stopped. By using the method, the vertical rigid body displacement recovery rate of the tunnel is close to 1.

Description

Technical Field

[0001] This invention relates to an active control grouting method, specifically to a method for restoring the horizontal rigid body displacement, vertical rigid body displacement, and ellipticity of a tunnel by combining vertical columnar grouting with multi-point grouting. Background Technology

[0002] High-rise buildings are being constructed more densely around subway lines; to maximize space utilization, buildings are maintaining a relatively small horizontal distance from subway lines, and the depth of building basements is gradually increasing. The excavation work for developing underground space inevitably causes deformation of the surrounding soil, which in turn causes deformation of the tunnel within the soil. This poses a threat to the structural and operational safety of the subway lines and presents new challenges to excavation design and construction techniques.

[0003] Numerous studies have reported cases where foundation pit construction has caused significant deformation in adjacent subway shield tunnels or station structures, even leading to serious defects such as segment cracking, wall cracking, and water leakage. To reduce the impact of foundation pit construction on adjacent existing tunnels, active and passive protection measures are often required. Passive protection measures mainly include: (1) strengthening the support system; (2) optimizing the excavation method; (3) reinforcing the soil in the pit; and (4) using isolation walls (piles). Passive measures usually result in a significant increase in foundation pit costs and a significant increase in construction time. In most cases, the above-mentioned passive measures are difficult to achieve millimeter-level deformation control of adjacent operational tunnels. Grouting is one of the active control measures, and grouting is widely used to lift buildings, tunnels, and pipelines. Grouting of adjacent existing tunnels can also purposefully induce a certain amount of horizontal deformation in the tunnel, thereby achieving active control and correction of the horizontal deformation of the tunnel through grouting. Grouting can simultaneously control both the horizontal and vertical deformation of the tunnel. Currently, there are many studies on grouting to lift existing buildings or tunnels, but few studies on grouting to control the horizontal deformation of tunnels. Moreover, existing studies are mostly engineering case studies, and there is a lack of systematic grouting theories and strategies for controlling both horizontal and vertical deformation of tunnels. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a method that can better restore the horizontal rigid body displacement, vertical rigid body displacement and ellipticity of tunnels, especially for vertical rigid body displacement, so that the vertical rigid body displacement recovery rate is close to 1 while restoring tunnel settlement and horizontal deformation.

[0005] To solve the above technical problems, the following technical solution is adopted.

[0006] This invention proposes a grouting method for simultaneously restoring tunnel settlement and horizontal deformation, comprising the following steps:

[0007] Step 1: Before excavating the foundation pit, numerical simulation software is used to obtain the location and size of the vertical grouting holes between the existing tunnel and the diaphragm wall at the outer wall of the foundation pit to be excavated, as well as the location and size of the inclined grouting holes with grout outlets located below the existing tunnel. Within the length of the foundation pit to be excavated, one vertical grouting hole and multiple inclined grouting holes are respectively set at the positions corresponding to each ring segment of the existing tunnel. The multiple inclined grouting holes are drilled into the ground from the side away from the foundation pit.

[0008] Step 2: Prepare the first grouting device and the second grouting device. Each of the first grouting device and the second grouting device includes a grouting pipe. Multiple grout outlet holes are opened on the lower end of the grouting pipe of the second grouting device. A bladder is fixed around the outer wall of the grouting pipe at the position corresponding to the multiple grout outlet holes.

[0009] Step 3: Drill holes according to the location and size of the vertical grouting holes and the location and size of each inclined grouting hole determined in Step 1;

[0010] Step 4: Insert a second grouting device into each vertical grouting hole, and insert a first grouting device into each inclined grouting hole;

[0011] Step 5: Excavate the foundation pit inside the diaphragm wall, and at the same time observe the data output by the displacement monitoring equipment installed at the monitoring points on the existing tunnel inner wall and track bed. If a certain ring segment causes displacement and deformation, grout is injected into the grouting pipe in the vertical grouting hole and the inclined grouting hole at the corresponding position of the ring segment. The displacement monitoring equipment includes tunnel horizontal displacement monitoring equipment, vertical displacement monitoring equipment, and ellipticity monitoring equipment.

[0012] Step Six: The grout flows into the sluice bag through the grout outlet in the grouting pipe of each vertically arranged second grouting device. The grout solidifies in the sluice bag inside the vertical grouting hole to form a vertical grout body. The grout flows out through the grouting pipe of the first grouting device in each inclined grouting hole to form multiple point grout bodies. During the grouting process, the displacement monitoring equipment installed in the existing tunnel is continuously observed. Grouting is stopped when the horizontal displacement, vertical displacement, and ellipticity of the tunnel return to the set values.

[0013] Compared with existing theories and technologies, the beneficial effects of this invention are as follows:

[0014] When a tunnel is in a settlement zone, vertical grouting between the tunnel and the foundation pit can effectively restore the tunnel's horizontal deformation, but it increases the tunnel's vertical deformation. Inclined grouting below and to the side of the tunnel can effectively lift it, but its effect on restoring horizontal deformation is relatively small. Therefore, a combined approach of vertical and inclined grouting is proposed to simultaneously control both horizontal and settlement deformations of the tunnel in the settlement zone, addressing the problem of only controlling horizontal deformation while neglecting settlement deformation during grouting. This combined approach can simultaneously and effectively restore the tunnel's horizontal rigid displacement, vertical rigid displacement, and ellipticity. Especially regarding vertical rigid displacement, the combined approach achieves a vertical rigid displacement recovery rate close to 1, while the recovery rate of vertical rigid displacement is only 0.15 under vertical grouting alone. Attached Figure Description

[0015] Figure 1 A schematic diagram of the bag grouting device before grouting, used in the grouting method of the present invention for simultaneously restoring tunnel settlement and horizontal deformation.

[0016] Figure 2 for Figure 1 The diagram shows the structure of the grouting device after grouting.

[0017] Figure 3 A schematic diagram of the combined structure of vertical grouting and multi-point grouting used in the grouting method of the present invention for simultaneously restoring tunnel settlement and horizontal deformation;

[0018] Figure 4 for Figure 3 The top view of the structure shown. Detailed Implementation

[0019] To make the objectives, solutions, and advantages of the present invention clearer, the present invention will be further described below with reference to the accompanying drawings and a specific embodiment.

[0020] The present invention provides a grouting method for simultaneously restoring tunnel settlement and horizontal deformation, comprising the following steps:

[0021] Step 1: Before excavating the foundation pit, numerical simulation software (including but not limited to Plaxis) can be used to obtain the location and size of the vertical grouting holes between the existing tunnel 1 and the diaphragm wall at the outer wall of the foundation pit to be excavated, as well as the location and size of the inclined grouting holes 5 located below the existing tunnel. Within the length of the foundation pit to be excavated, and at positions corresponding to each ring segment of the existing tunnel 1, one vertical grouting hole and multiple inclined grouting holes (e.g., ...) are respectively set. Figure 4 As shown, there can be 3 (in order to achieve a better repair effect).

[0022] The multiple inclined grouting holes are drilled into the ground from the side away from the foundation pit. Preferably, the line connecting the center points of the bottom of the multiple inclined grouting holes at the corresponding positions of each ring segment is set perpendicular to the central axis of the tunnel, which can avoid disturbing the foundation pit and avoid damaging the integrity of the diaphragm wall.

[0023] Step 2: Prepare the first grouting device and the second grouting device. Each of the first grouting device and the second grouting device includes a grouting pipe 4. Multiple grout outlet holes are opened on the lower end of the grouting pipe 4 of the second grouting device. A bag 8 is fixedly ringed on the outer wall of the grouting pipe 4 at the position corresponding to the multiple grout outlet holes. The grouting pipe 4 can be composed of multiple pipe sections that are fixedly connected vertically. The bag and the grouting pipe can be connected by a ring clamp 7.

[0024] Step 3: Drill holes according to the position and size of the vertical grouting hole 4 and the position and size of each inclined grouting hole as determined in Step 1;

[0025] Step 4: Insert a second grouting device into each vertical grouting hole, and insert a first grouting device into each inclined grouting hole 5;

[0026] Step 5: Excavate the foundation pit inside the diaphragm wall, and simultaneously observe the displacement monitoring equipment installed at the monitoring points on the existing tunnel inner wall and track bed. If a certain ring segment experiences displacement and deformation, inject grouting pipe 4 (according to) into the vertical grouting hole and the oblique grouting hole at the corresponding position of that ring segment. Figure 4 Grouting is performed inside the grouting pipes (as shown in the diagram). The displacement monitoring equipment includes tunnel horizontal displacement monitoring equipment, vertical displacement monitoring equipment, and ellipticity monitoring equipment.

[0027] The displacement monitoring equipment described above can be used for automated monitoring of vertical displacement using a hydrostatic level, and for monitoring of horizontal displacement using a displacement sensor. The tunnel convergence, i.e., ellipticity, can be monitored using a laser rangefinder. Of course, any existing equipment capable of monitoring displacement and deformation can be used, and it is not limited to the above-mentioned equipment. For detection methods, please refer to the instruction manual of the corresponding monitoring equipment.

[0028] Step Six: The grout flows into the slurry bags 8 through the outlet holes in the grouting pipes of the second grouting devices installed vertically. The grout solidifies in the slurry bags 8 within the vertical grouting holes to form vertical grout bodies 2. The grout flows out through the grouting pipes of the first grouting devices in the oblique grouting holes to form multiple point grout bodies 6. During the grouting process, the output data of the displacement monitoring equipment installed in the existing tunnel is continuously observed. Grouting is stopped when the tunnel's horizontal displacement, vertical displacement, and ellipticity return to the set values.

[0029] The shortest horizontal distance b between the vertical grouting body 2 and the existing tunnel 1 along the horizontal axis of the existing tunnel is 3m-3.5m, and the vertical distance a between the horizontal centerline of the vertical grouting body and the horizontal axis of the tunnel is 1m. The length L of the vertical grouting body can be 5m-6m.

[0030] Preferably, when grouting into the inclined grouting holes, grout is injected sequentially into the grouting pipe 4 from the side furthest from the foundation pit towards the pit side. Simultaneously, the data output by the displacement monitoring equipment is observed. Grouting stops when the grout volume at each point reaches the expected grout volume. Generally, the closer to the foundation pit, the greater the grout volume injected into the grouting pipe 4. If the final effect deviates from the expected effect, grout can be injected into the corresponding grouting pipe as needed to correct it. The specific grout volume can be estimated in actual engineering projects using numerical simulation software (such as, but not limited to, Plaxis) to simulate the grout volume at the three points.

[0031] The preferred angle B between the grouting pipe in the inclined grouting hole and the horizontal direction is 40° to 45°. The line connecting the midpoint of the horizontal line where the three grout outlets are located and the center of the existing tunnel 1 coincides with the vertical axis passing through the center of the existing tunnel. The distance c2 between the midpoint of the horizontal line where the three grout outlets are located and the outer contour of the existing tunnel 1 is 3m to 3.5m. The spacing between the centers of two adjacent grouting points is 2m to 2.5m. Multi-point grouting can achieve uniform vertical lifting of the tunnel. The combination of multi-point grouting and vertical grouting can simultaneously repair tunnel deformation and rigid displacement.

[0032] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A method of grouting for simultaneously recovering both settlement and horizontal deformation of a tunnel, characterized by, The application relates to a method for recovering tunnel horizontal rigid displacement, vertical rigid displacement and ellipticity, wherein the recovery rate of the tunnel vertical rigid displacement is close to 1, and the method comprises the following steps: Step one: before a foundation pit is dug, the positions and sizes of vertical grouting holes between a diaphragm wall and an existing tunnel and a foundation pit to be dug are obtained through numerical simulation, and the positions and sizes of inclined grouting holes with grouting outlets below the existing tunnel are obtained; a vertical grouting hole and multiple inclined grouting holes are arranged at positions corresponding to each ring of the existing tunnel in the length range of the foundation pit to be dug; the multiple inclined grouting holes are drilled into the ground from the ground far away from the foundation pit; Step two: a first grouting device and a second grouting device are prepared, each of the first grouting device and the second grouting device comprises a grouting pipe, a plurality of grouting outlets are formed in the pipe wall of the lower end of the grouting pipe of the second grouting device, and a bag is fixedly sleeved on the outer wall of the grouting pipe at positions corresponding to the grouting outlets; Step three: holes are drilled according to the positions and sizes of the vertical grouting holes and the positions and sizes of the inclined grouting holes determined in step one; Step four: the second grouting device is inserted into each vertical grouting hole, and the first grouting device is inserted into each inclined grouting hole; Step five: the foundation pit is dug on the inner side of the diaphragm wall, meanwhile, the output data of displacement monitoring equipment arranged at monitoring points on the inner wall of the existing tunnel and the track bed are observed, if displacement and deformation occur in a ring of the existing tunnel, grouting is performed in the grouting pipes in the vertical grouting hole and the inclined grouting hole at the position corresponding to the ring of the existing tunnel; the displacement monitoring equipment comprises tunnel horizontal displacement monitoring equipment, vertical displacement monitoring equipment and ellipticity monitoring equipment; Step six: grouting liquid flows into the bag at the grouting outlets in the grouting pipes of the second grouting device arranged in the vertical direction, the grouting liquid solidifies to form a vertical grouting body at the bag in the vertical grouting hole, and the grouting liquid flows out of the grouting pipes of the first grouting device in the inclined grouting holes to form multiple point grouting bodies; during the grouting process, the displacement monitoring equipment arranged in the existing tunnel is continuously observed, and the grouting is stopped when the tunnel horizontal displacement, the vertical displacement and the ellipticity recover to the set values; The included angle B between the grouting pipe in the inclined grouting hole and the horizontal direction is 40-45 degrees, the center line between the center points of the horizontal lines of the three grouting outlets coincides with the vertical axis direction through the center of the existing tunnel, and the distance between the center line and the outer contour of the existing tunnel is 3-3.5 m, and the distance between the centers of two adjacent point grouting bodies is 2-2.5 m.

2. The method of claim 1, wherein: The center line between the center points of the hole bottoms of the multiple inclined grouting holes at the positions corresponding to each ring of the existing tunnel is arranged perpendicularly to the center axis of the tunnel.

3. The method of claim 2, wherein: The shortest horizontal distance between the vertical grouting body and the existing tunnel along the horizontal axis direction of the existing tunnel is 3-3.5 m, the vertical distance between the horizontal center line of the vertical grouting body and the horizontal axis of the tunnel is 1 m, and the length of the vertical grouting body is 5-6 m.

4. The method of claim 3, wherein: When grouting in the inclined grouting hole, grouting is sequentially carried out from the side far from the foundation pit to the side of the foundation pit, and the output data of the monitoring equipment is observed during grouting, and grouting is stopped when the grouting amount of each point reaches the expected grouting amount.

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