Regional soil body reinforcement construction method between small-clear-distance shield tunnels

Abstract

The invention discloses a regional soil body reinforcement construction method between small-clear-distance shield tunnels. The regional soil body reinforcement construction method comprises the following steps that materials of the shield tunnels constructed on site, the shape of the shield tunnels, the distance between shield tunnel soil bodies and parameters of soil layers are obtained; a three-dimensional shield tunnel model is established based on the obtained data, and soil stress distribution parameters are obtained through model simulation; based on the soil stress distribution parameters, an area with the most concentrated stress above the newly-built shield tunnel is divided into a strong reinforcement area, stress sub-concentrated areas located on the two sides of the periphery of the strong reinforcement area are divided into medium-strong reinforcement areas, and areas located on the two sides of the periphery of the medium-strong reinforcement areas are divided into weak reinforcement areas; and the strong reinforcement area is reinforced through double-liquid type mixed liquid, then the medium-strong reinforcement area is reinforced through cement paste, and finally the weak reinforcement area is reinforced through clay paste. Regional soil body reinforcement is adopted, the reinforcement strength is controlled, disturbance to the existing shield tunnel is reduced, and the engineering quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, in particular to a regional soil reinforcement construction method between shield tunnels with a small clearance. Background Art

[0002] Close-spacing tunnels are special tunnel arrangements where the thickness of the medium rock wall is less than the minimum clearance required for separate, independent twin tunnels. With the increasing number of urban subway construction projects in recent years, subway tunnel construction has faced increasingly complex conditions. This is particularly true when constructing new shield tunnels in close proximity to existing ones.

[0003] During the shield advancement process of a new tunnel, due to the uncertainty of geological conditions, such as the heterogeneity of the rock and soil, the heterogeneity of the rock and soil near soft soil layers, gravel belts or unstable groundwater belts may cause ground subsidence and deformation of the tunnel structure to varying degrees; at the same time, during the design and construction of the new tunnel, errors may occur in the positioning of parameters such as the tunnel excavation position, depth or inclination angle, especially when crossing an existing tunnel, which may cause the new tunnel to be too close to or intersect with the existing tunnel, causing disturbance to the existing tunnel and then damaging its structure, leading to safety hazards such as tunnel deformation or even collapse. Therefore, reinforcement construction is required between the new shield tunnel and the existing shield tunnel to avoid damage.

[0004] Existing tunnel construction reinforcement measures usually involve direct integral grouting reinforcement between the new tunnel and the existing tunnel. However, in actual projects, this traditional grouting reinforcement method may have significant differences in geological conditions, tunnel stress conditions, and construction impact range in different regions. In this way, integral grouting will result in an excessively large grouting range, making it difficult to control the grouting reinforcement strength. Too low a strength may lead to construction accidents, while too high a strength may lead to waste of resources. In addition, integral grouting reinforcement may cause unnecessary disturbances to the existing tunnel structure, especially when the existing tunnel structure itself is relatively fragile. Such disturbances may aggravate its damage, thereby affecting the long-term stability of the tunnel. Summary of the Invention

[0005] The purpose of the present invention is to provide a regional soil reinforcement construction method between shield tunnels with small clearance, so as to solve the problem that when a new shield tunnel passes through an existing shield tunnel for reinforcement, it is difficult to control the reinforcement strength and it is easy to cause disturbance to the existing tunnel structure.

[0006] The technical solution of the present invention is: A method for regional soil reinforcement construction between shield tunnels with small clearance includes the following steps: Obtain the material of the shield tunnel under construction on site, the shape of the shield tunnel, the distance between the shield tunnel soil bodies, and the parameters of the soil layer; A 3D shield tunnel model is constructed based on the material, shape, distance between the shield tunnel soil, and soil layer parameters of the shield tunnel being constructed on site. The soil stress distribution parameters are obtained through simulation using the established 3D shield tunnel model. Based on soil stress distribution parameters, the area with the most concentrated stress in the existing shield tunnel is divided into a strong reinforcement area, the areas with less concentrated stress on both sides of the strong reinforcement area are divided into medium-strong reinforcement areas, and the areas on both sides of the medium-strong reinforcement area are divided into weak reinforcement areas. The divided areas are reinforced separately. First, the strong reinforcement area is reinforced with a two-liquid mixed liquid, then the medium reinforcement area is reinforced with cement slurry, and finally the weak reinforcement area is reinforced with clay slurry.

[0007] Preferably, as a further improvement of the present invention, the two-liquid mixed liquid is a mixture of cement and water glass.

[0008] Preferably, as a further improvement of the present invention, during the partition reinforcement process, an arc-shaped protective shell is formed by performing grouting reinforcement construction at the boundaries of the strong reinforcement area, the medium-strong reinforcement area and the weak reinforcement area.

[0009] Preferably, as a further improvement of the present invention, the grouting reinforcement construction includes the following steps: Locate the location of the jet grouting holes; Pre-buried grouting pipes in the grouting holes; Reinforcement is done by high-pressure jet grouting through the grouting pipe.

[0010] Preferably, as a further improvement of the present invention, there are multiple groups of pre-buried grouting pipes, and the multiple groups of pre-buried grouting pipes are evenly distributed along the axial direction of the existing shield tunnel, and the spacing between adjacent groups of pre-buried grouting pipes is 2m. Each group of pre-buried grouting pipes includes six pre-buried grouting pipes, and is arranged radially along the existing shield tunnel, and the angle between two adjacent pre-buried grouting pipes is 15°.

[0011] Preferably, as a further improvement of the present invention, the step of obtaining soil stress distribution parameters by simulating the established three-dimensional shield tunnel model includes the following steps: The measured shield tunnel material, shield tunnel shape, distance between shield tunnel soils, soil layer parameters, established tunnel material properties, and imposed boundary condition constraints are substituted into the 3D shield tunnel model. The 3D shield tunnel model obtains the optimal boundary condition parameters through simulation calculation and adjustment of various parameters. The three-dimensional shield tunnel model is simulated according to the optimal boundary condition parameters to obtain the soil stress distribution parameters of the three-dimensional shield tunnel model.

[0012] Preferably, as a further improvement of the present invention, the reinforcement construction process further includes the following steps: Monitoring equipment components are deployed in the existing shield tunnel. During the construction of the new shield tunnel, the existing shield tunnel is monitored throughout the entire process through the monitoring equipment components. The shield excavation parameters of the new shield tunnel are adjusted according to the monitoring results, and the reinforcement plan is changed in real time.

[0013] Preferably, as a further improvement of the present invention, the monitoring equipment components are arranged in multiple groups at intervals along the axial direction of the existing shield tunnel, and each group of monitoring equipment components includes a multi-point displacement meter and a soil pressure sensor. The multi-point displacement meter is used to monitor the displacement changes of the surrounding rock around the existing shield tunnel, and the soil pressure sensor is used to monitor the soil pressure distribution around the existing shield tunnel.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Model the construction process of a new shield tunnel passing over an existing shield tunnel, calculate in advance the soil stress distribution parameters near the construction process of the new shield tunnel passing over the existing shield tunnel model, determine the impact range based on the modeling analysis, and reinforce the soil within the impact range in different areas, thereby reducing the disturbance to the existing shield tunnel during shield construction.

[0015] 2. The use of regional soil reinforcement can effectively alleviate safety pressures during construction, ensure project quality, and improve construction efficiency. It is applicable to tunnel geological conditions with complex terrain conditions. In addition, reinforcement materials can be selected according to project needs, achieving cost savings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flowchart of a method for regional soil reinforcement construction between shield tunnels with small clearance.

[0017] Figure 2 The figure is a schematic diagram of the construction structure of a method for reinforcing soil in different regions between shield tunnels with small clearance according to the present invention.

[0018] Figure 3 The present invention provides a cross-sectional schematic diagram of the arrangement of grouting pipes for a construction method for regional soil reinforcement between shield tunnels with a small clearance. DETAILED DESCRIPTION

[0019] The following combination Figures 1 to 3, a detailed description of the specific embodiments of the present invention is provided. In the description of the invention, it should be understood that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limiting the present invention.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of the invention, unless otherwise specified, "plurality" means two or more.

[0021] Example like Figure 1 As shown, an embodiment of the present invention provides a method for regional soil reinforcement construction between shield tunnels with small clearance, comprising the following steps: S1. Obtain the material of the shield tunnel under construction on site, the shape of the shield tunnel, the distance between the shield tunnel soil bodies, and the parameters of the soil layer.

[0022] S2. Based on the materials, shapes, and distances between soil bodies and soil layer parameters of the shield tunnel constructed on-site, a three-dimensional shield tunnel model was constructed using Plaxis3D modeling. The materials, shapes, and distances between soil bodies of the shield tunnel were simulated. The measured parameters, established material properties, and boundary condition constraints were substituted into the three-dimensional shield tunnel model. Through simulation calculations, various parameters were adjusted to obtain the optimal values, which were the corresponding optimal boundary condition parameters. The soil stress distribution parameters of the three-dimensional shield tunnel model were obtained based on the optimal boundary condition parameters.

[0023] Specifically, the simulation scheme is determined by optimizing the boundary condition parameters. The soil stress distribution parameters of the entire 3D shield tunnel model are obtained from the simulation results.

[0024] For example, a new tunnel was constructed using the TMB shield method, with four simulation scenarios. The specific scenarios are as follows: Scheme 1: Using a 2m advance, excavating a total of 24m, the soil between the existing and excavated tunnels was reinforced with a concrete cube measuring 34m long, 10m wide, and 1m high. Scheme 2: Using a 3m advance, excavating a total of 24m, the soil between the existing and excavated tunnels was reinforced with a concrete cube measuring 34m long, 10m wide, and 1m high. Scheme 3: Using a 3m advance, excavating a total of 24m, no soil reinforcement was performed between the existing and excavated tunnels. Scheme 4: Using a 4m advance, excavating a total of 24m, the soil between the existing and excavated tunnels was reinforced with a concrete cube measuring 34m long, 10m wide, and 1m high.

[0025] Among them, the height range of the warning value of the soil stress distribution parameter is 2 / 3 of the tunnel cross section, such as Figure 2 As shown, the plane range of the warning value is a fan-shaped area formed by 45° on both sides above the center line of the existing shield tunnel 2 with the center of the existing shield tunnel 2 as the center of the circle.

[0026] S3. Based on the soil stress distribution parameters, the area above the newly built shield tunnel 1 with the most concentrated stress is divided into the strongly reinforced area 3, the areas with less concentrated stress on both sides of the strongly reinforced area 3 are divided into the medium-strong reinforced area 4, and the areas on both sides of the medium-strong reinforced area 4 are divided into the weakly reinforced area 5.

[0027] Specifically, according to the actual working conditions of on-site construction, finite element modeling simulation is carried out, and Plaxis3D modeling calculation is used to accurately calculate the impact range of the new shield tunnel 1 on the existing shield tunnel 2 structure during the excavation process. The impact range is 2 / 3 of the tunnel cross section. The length of the impact range is determined according to the length of the new shield tunnel 1 passing through the existing shield tunnel 2 to ensure that the impact range can completely cover the soil range that may be disturbed during the actual construction process. Figure 2 As shown, the plane range of the warning value is a fan-shaped area formed at 45° on both sides above the center line of the existing shield tunnel 2 with the center of the existing shield tunnel 2 as the center of the circle. The fan-shaped area is divided into six equal small fan-shaped areas. The two equal small fan-shaped areas in the middle are divided into strong reinforcement areas 3 as the stress concentration areas, and the small fan-shaped areas on both sides of the strong reinforcement area 3 are divided into medium-strong reinforcement areas 4 as the stress concentration areas. The small fan-shaped areas on both sides of the medium-strong reinforcement area 4 are divided into weak reinforcement areas 5.

[0028] S4, the divided areas are reinforced separately. The strong reinforcement area 3 is where the stress is most concentrated and should be reinforced first. Therefore, a two-liquid mixture of cement and water glass is used for reinforcement. It has the advantage of high strength and can meet the reinforcement stress requirements. After the mixture in the strong reinforcement area solidifies, the medium-strong reinforcement area 4 is reinforced using 425 cement slurry. Finally, ordinary clay slurry is used to reinforce the weak reinforcement area 5.

[0029] In the process of zone reinforcement, an arc-shaped protective shell is formed by performing grouting reinforcement construction at the boundaries of the strong reinforcement area 3, the medium-strong reinforcement area 4 and the weak reinforcement area 5.

[0030] Grouting reinforcement construction includes measuring and locating the position of the jet grouting holes, pre-buried grouting pipes 6 in the grouting holes, and performing high-pressure jet grouting reinforcement construction through the grouting pipes 6. The jet grouting holes are measured and located. According to the positioning in the simulation plan, the jet grouting holes are selected in the tunnel for drilling. The diameter of each drilled hole is a small hole of 50mm. The pre-buried grouting pipes 6 are 50mm in diameter and 5mm in wall thickness. Figure 3 As shown, there are multiple groups of pre-buried grouting pipes 6, which are evenly distributed along the axial direction of the existing shield tunnel 2, and the spacing between adjacent groups of pre-buried grouting pipes 6 is 2m. Each group of pre-buried grouting pipes 6 includes six pre-buried grouting pipes 6, and are arranged radially along the existing shield tunnel 2. The angle between two adjacent pre-buried grouting pipes 6 is 15°.

[0031] S5. Deploy monitoring equipment components in the existing shield tunnel 2. During the construction of the new shield tunnel 1, the monitoring equipment components are used to monitor the entire process of the existing shield tunnel 2. Adjust the shield excavation parameters of the new shield tunnel 1 and change the reinforcement plan in real time based on the monitoring results.

[0032] Among them, there are multiple groups of monitoring equipment components arranged at intervals along the axial direction of the existing shield tunnel 2. Each group of monitoring equipment components includes a multi-point displacement meter and an earth pressure sensor. The multi-point displacement meter is used to monitor the displacement changes of the surrounding rock around the existing shield tunnel 2, and the earth pressure sensor is used to monitor the soil pressure distribution around the existing shield tunnel 2. Through the above settings, real-time monitoring of the entire process of the existing shield tunnel 2 is guaranteed to ensure the safety of the existing shield tunnel 2 and the smooth construction of the shield tunnel 1, while ensuring the impact of land displacement.

[0033] During shield tunneling construction of the new shield tunnel 1, monitoring equipment is deployed within the existing shield tunnel 2 to monitor the entire process. Based on the monitoring results, shield tunneling parameters for shield tunnel 1 are adjusted promptly to ensure the safety of the existing shield tunnel 2. Furthermore, the reinforcement scope and concrete strength are modified based on the monitoring parameters. For example, if soil displacement during tunneling exceeds the specified range, the reinforcement scope and the strength of the reinforcement materials are expanded. If there is no significant change in soil displacement during tunneling, the reinforcement scope can be appropriately reduced and more efficient reinforcement materials can be used, thereby saving materials.

[0034] In summary, this invention employs regional soil reinforcement, effectively alleviating safety pressures during construction, ensuring project quality, and improving construction efficiency. It is applicable to tunnels with complex geological and topographical conditions. Furthermore, reinforcement materials can be selected based on project needs, achieving cost savings. This method offers significant social and economic benefits.

[0035] The above disclosures are only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A method for regional soil reinforcement construction between shield tunnels with small clearance, characterized in that: The following steps are involved: Obtain the material of the shield tunnel under construction on site, the shape of the shield tunnel, the distance between the shield tunnel soil bodies, and the parameters of the soil layer; A 3D shield tunnel model is constructed based on the material, shape, distance between the shield tunnel soil, and soil layer parameters of the shield tunnel being constructed on site. The soil stress distribution parameters are obtained through simulation using the established 3D shield tunnel model. Based on the soil stress distribution parameters, the area above the existing shield tunnel (2) with the most concentrated stress is divided into a strong reinforcement area (3), the areas with less concentrated stress on both sides of the strong reinforcement area (3) are divided into medium-strong reinforcement areas (4), and the areas on both sides of the medium-strong reinforcement area (4) are divided into weak reinforcement areas (5); The divided areas are reinforced in sections. First, a two-liquid mixture is used to reinforce the strong reinforcement area (3). Then, cement slurry is used to reinforce the medium-strength reinforcement area (4). Finally, clay slurry is used to reinforce the weak reinforcement area (5).

2. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 1 is characterized in that: The two-liquid mixed liquid is a mixed liquid of cement and water glass.

3. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 1 is characterized in that: During the partition reinforcement process, an arc-shaped protective shell is formed by performing grouting reinforcement construction at the boundaries of the strong reinforcement area (3), the medium-strong reinforcement area (4) and the weak reinforcement area (5).

4. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 3 is characterized in that: The grouting reinforcement construction comprises the following steps: Locate the location of the jet grouting holes; Pre-buried grouting pipe (6) in the grouting hole; The reinforcement is carried out by high pressure jet grouting through the grouting pipe (6).

5. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 4 is characterized in that: There are multiple groups of pre-buried grouting pipes (6), which are evenly distributed along the axial direction of the existing shield tunnel (2), and the spacing between adjacent groups of pre-buried grouting pipes (6) is 2m. Each group of pre-buried grouting pipes (6) includes six pre-buried grouting pipes (6) and is arranged along the radial direction of the existing shield tunnel (2), and the angle between two adjacent pre-buried grouting pipes (6) is 15°.

6. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 1, characterized in that: The method of simulating and obtaining soil stress distribution parameters by establishing a three-dimensional shield tunnel model includes the following steps: The measured shield tunnel material, shield tunnel shape, distance between shield tunnel soils, soil layer parameters, established tunnel material properties, and imposed boundary condition constraints are substituted into the 3D shield tunnel model. The 3D shield tunnel model obtains the optimal boundary condition parameters through simulation calculation and adjustment of various parameters. The three-dimensional shield tunnel model is simulated according to the optimal boundary condition parameters to obtain the soil stress distribution parameters of the three-dimensional shield tunnel model.

7. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 1, characterized in that: The reinforcement construction process also includes the following steps: A monitoring device assembly is arranged in the existing shield tunnel (2), and during the construction of the new shield tunnel (1), the entire process of the shield tunnel (2) is monitored by the monitoring device assembly, and shield excavation parameters of the new shield tunnel (1) are adjusted and reinforcement plans are changed in real time according to the monitoring results.

8. The method for regional soil reinforcement between shield tunnels with small clearance according to claim 7, characterized in that: The monitoring equipment components are arranged in multiple groups at intervals along the axis direction of the existing shield tunnel (2), and each group of monitoring equipment components includes a multi-point displacement meter and an earth pressure sensor. The multi-point displacement meter is used to monitor the displacement change of the surrounding rock around the existing shield tunnel (2), and the earth pressure sensor is used to monitor the pressure distribution of the soil around the existing shield tunnel (2).

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