A method for repairing convergence deformation of shield tunnels

Abstract

The present invention relates to the technical field of soil reinforcement for underground tunnel engineering, and in particular to a method for repairing the convergence deformation of an operating shield tunnel in a soft soil area, comprising the following steps: S1 determining the diffusion range of a grouting body and the range of a plastic influence zone, S2 adding drainage measures according to the determined diffusion range of the grouting body and the range of the plastic influence zone, eliminating the excess pore water pressure caused in the pressure grouting process, increasing the grouting efficiency, and avoiding the rebound of the lateral convergence deformation of the tunnel after construction; the drainage measures include inserting a vertical pore pressure dissipation drainage body (4) in an influence zone (3) between a grouting hole (1) and a tunnel (2), and the vertical pore pressure dissipation drainage body (4) must pass through the height range of a grouting body (5); the present invention can improve the efficiency of grouting to repair deformation, and solve the problem of repeated grouting caused by rebound after grouting to repair tunnel deformation in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of soil reinforcement for underground tunnel engineering, and in particular to a method for repairing convergence deformation of an operating shield tunnel in a soft soil area. Background Art

[0002] In recent years, with the development of the national economy and the acceleration of urbanization, the construction of domestic urban rail transit has also developed rapidly. The construction of subways is accompanied by an increase in development activities along the line. The surrounding environment faced by engineering construction is becoming more and more complex, and the pressure on the operation and supervision of subway tunnels is increasing. Through long-term monitoring and maintenance of shield tunnels in soft soil areas, it is found that tunnel diseases are closely related to structural deformation. Excessive deformation of the transverse diameter of the tunnel will cause water leakage at the joints of the pipe segments or pressure loss of the pipe segments. In severe cases, it may cause tunnel collapse and cause adverse effects.

[0003] The existing technology mainly controls the lateral convergence deformation of repaired operating tunnels through grouting reinforcement. For example, a grouting pipe is vertically lowered from the ground outside the tunnel to the bottom of the tunnel, and then the pipe is pulled out to grout to control the lateral convergence deformation. The grouting holes are distributed on both sides of the tunnel and kept at a certain distance from the tunnel.

[0004] In many cities in coastal soft soil areas such as Shanghai and Ningbo, a large number of shield tunnels are usually buried in weak flow plastic clay or silty clay, and pressure grouting can easily cause excess pore water pressure in the soil layer. With the end of pressure grouting, the excess pore water pressure continues and gradually dissipates over time. Although the lateral diameter convergence deformation of the tunnel was repaired during the grouting process, with the dissipation of the excess pore water pressure, the effective stress in the soil increased, accompanied by soil compression, which may cause the lateral convergence deformation rebound of the repaired tunnel. Through long-term deformation monitoring of shield tunnels, it was found that the lateral convergence deformation of the tunnel repaired by grouting in soft soil areas accounted for about 20% to 50%, and even more so, it reached 60%. Summary of the invention

[0005] In order to overcome the defects of the above-mentioned prior art, the present invention provides a method for repairing the convergence deformation of a shield tunnel. During the grouting process, drainage measures are added to dissipate the pore pressure, which can improve the efficiency of grouting to repair deformation and solve the problem of repeated grouting caused by rebound after grouting to repair tunnel deformation in the prior art.

[0006] The technical solution of the present invention is as follows:

[0007] A method for repairing lateral convergence deformation of a shield tunnel comprises the following steps:

[0008] S1 determines the diffusion range of the grouting body and the range of the plastic influence zone.

[0009] S2 According to the determined grouting body diffusion range and plastic influence zone range, drainage measures are added to eliminate the excess pore water pressure caused by the pressure grouting process, increase the grouting efficiency, and avoid the lateral convergence deformation rebound of the tunnel after construction;

[0010] The drainage measures include inserting a vertical pore pressure dissipation drainage body in the influence area between the grouting hole and the tunnel, and the vertical pore pressure dissipation drainage body must pass through the height range of the grouting body.

[0011] Furthermore, in the above-mentioned method for repairing the lateral convergence deformation of a shield tunnel, the diffusion range of the grouting body in step S1 must be determined based on the grouting volume and the height of the grouting body. If there is no bag grouting, it is assumed that the grouting body is evenly diffused to form a cylindrical slurry.

[0012] Furthermore, in the above-mentioned method for repairing the lateral convergence deformation of a shield tunnel, the range of the plastic influence zone in step S1 is based on the small hole cylindrical expansion theory. It is assumed that the grouting body is cylindrical in the soil, and the compaction grouting process is equivalent to expanding a small hole with a radius of r in an infinite soil body, forming a stress influence zone around the hole, which is the plastic influence zone.

[0013] Furthermore, in the above method for repairing the lateral convergence deformation of a shield tunnel, the grouting body diffusion radius r and the plastic influence zone radius r p The relationship is

[0014] In the formula, r p is the influence radius of the plastic zone; E is the elastic modulus of the soil; v is the Poisson's ratio; c u It is the undrained shear strength of soil.

[0015] Furthermore, in the above-mentioned method for repairing the lateral convergence deformation of a shield tunnel, the vertical pore pressure dissipation drainage body is one or more drainage materials selected from the group consisting of a water collection well, a pipe well, a vertical plastic drainage board, cardboard, a sand pile, a bagged sand well, and a gravel pile.

[0016] Furthermore, in the above-mentioned method for repairing the lateral convergence deformation of a shield tunnel, the drainage measures must be set within the plastic influence zone near the tunnel side.

[0017] Furthermore, in the above-mentioned method for repairing the lateral convergence deformation of a shield tunnel, the drainage measure, if it is slurry bag grouting, also includes a slurry bag added to the outside of the grouting pipe, which can form a drainage channel to discharge the pore water of the soil and accelerate the consolidation of the soil, and can also limit the random diffusion of the slurry to form a complete and regular grouting body.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention can avoid the generation of excess pore water pressure during the grouting process by arranging drainage measures within the plastic stress influence zone, thereby avoiding the rebound of the expected repaired lateral convergence deformation, improving the grouting efficiency, and avoiding repeated grouting to disturb the shield tunnel in operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the lateral convergence deformation repaired by grouting outside the tunnel according to the present invention;

[0021] Among them: grouting hole 1, tunnel 2, affected area 3, vertical pore pressure dissipation drainage body 4, grouting body 5, grouting pipe 6, grouting bag 7. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0027] Example 1

[0028] refer to Figure 1 shown.

[0029] This embodiment is a method of repairing the lateral convergence deformation of a tunnel by grouting outside the tunnel. A vertical pore pressure dissipation drainage body 4 is inserted into the influence area 3 between the grouting hole 1 and the tunnel 2. The vertical pore pressure dissipation drainage body can be one or more drainage materials such as a water collection well, a pipe well, a vertical plastic drainage board, a cardboard, a sand pile, a bagged sand well, and a gravel pile. The vertical pore pressure dissipation drainage body 4 must pass through the height range of the grouting body 5.

[0030] Before implementing this example, it is necessary to clarify the buried soil layer of the tunnel, that is, the soil layer of the grouting body. According to the distance between the grouting hole and the outer edge of the tunnel, the relevant grouting parameters, such as the grouting volume and the height of the grouting body, can be determined by trial grouting. Based on this, the diffusion radius r of the grouting body can be approximately calculated. The range of the grouting plastic influence zone can be further calculated in combination with the soil layer parameters, and pore pressure dissipation measures can be set in the influence zone to improve the grouting efficiency.

[0031] For example, the shield tunnel in the soft soil area of ​​Shanghai is buried in the ④ layer of gray silty clay layer, and grouting is carried out in the ④ layer of soil to repair the lateral convergence deformation of the tunnel. Assuming that the grouting hole is 3.0m away from the outer edge of the tunnel, the grouting test determines that the grouting body height is 4.0m, and the grouting volume is about 1400L. The calculation shows that the grouting body diffusion radius r is about 0.33m. The plastic influence zone radius r is further calculated based on the ④ layer soil parameters. p It is about 2.6 to 3.0 m. Vertical pore pressure dissipation drainage bodies can be arranged accordingly.

[0032] Example 2

[0033] refer to Figure 1 shown.

[0034] This embodiment is a method of repairing the lateral convergence deformation of the tunnel by grouting with a bag outside the tunnel. The difference from the first embodiment is that a slurry bag 7 is added outside the grouting pipe 6 to limit the slurry from spreading and forming a complete grouting body 5, thereby achieving the purpose of compacting and reinforcing the soil. The slurry bag 7 can be made of geotextile and is made according to a certain diameter and length according to the determined grouting amount and grouting body height.

[0035] The above are only preferred embodiments of the present invention, and the protection scope of the present invention cannot be limited thereto. That is, any simple equivalent changes and modifications made according to the claims and the content of the invention still fall within the protection scope of the patent application of the present invention.

Claims

1. A method for repairing the lateral convergence deformation of a shield tunnel, characterized in that: The following steps are involved: S1 determines the diffusion range of the grouting body and the range of the plastic influence zone; S2 According to the determined grouting body diffusion range and plastic influence zone range, drainage measures are added to eliminate the excess pore water pressure caused by the pressure grouting process, increase the grouting efficiency, and avoid the lateral convergence deformation rebound of the tunnel after construction; The drainage measures include inserting a vertical pore pressure dissipation drainage body (4) in the influence area (3) between the grouting hole (1) and the tunnel (2), and the vertical pore pressure dissipation drainage body (4) must pass through the height range of the grouting body (5); The diffusion range of the grouting body in step S1 must be determined according to the grouting amount and the height of the grouting body. If there is no bag grouting, it is assumed that the grouting body is evenly diffused to form a cylindrical slurry; The range of the plastic influence zone in step S1 is based on the small hole cylindrical expansion theory. Assuming that the grouting body is cylindrical in the soil, the compaction grouting process is equivalent to expanding a small hole with a radius of r in the infinite soil, forming a stress influence zone around the hole, which is the plastic influence zone; Grout diffusion radius r and plastic influence zone radius r p The relationship is In the formula, r p is the influence radius of the plastic zone; E is the elastic modulus of the soil; v is the Poisson's ratio; c u is the undrained shear strength of soil; Where: grouting body diffusion radius r = 0.33m, plastic influence zone radius r p =2.6-3.0m; The vertical pore pressure dissipation drainage body (4) is one or more drainage materials selected from the group consisting of a water collection well, a pipe well, a vertical plastic drainage board, a cardboard, a sand pile, a bagged sand well, and a sand and gravel pile; The drainage measures mentioned above shall be set within the plastic influence zone near the tunnel side; The drainage measure, if it is slurry bag grouting, also includes a slurry bag (7) added outside the grouting pipe (6), which can form a drainage channel to discharge soil pore water, accelerate soil consolidation, and limit the slurry from spreading randomly to form a complete and regular grouting body (5).

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