Shallow-buried tunnel pipe roofing stress monitoring system

Abstract

The utility model discloses a shallow-buried tunnel pipe curtain stress monitoring system which comprises an arc-shaped pipe curtain arranged below an overburden layer, the arc-shaped pipe curtain is composed of a plurality of steel pipes arranged side by side, the length direction of the steel pipes is in the passing direction of a tunnel, and the contour line of the arc-shaped pipe curtain is consistent with the vault of the tunnel; a plurality of vibrating wire type stress sensors are arranged along the length direction of each steel pipe, the vibrating wire type stress sensors are mounted between clamping seats and arc-shaped buckles, and the clamping seats are welded above the steel pipes; and a signal line of the vibrating wire type stress sensor is electrically connected with an external signal acquisition device. An array type monitoring system surrounding the whole pipe roofing in all directions is formed, the stress state of the pipe roofing is sensed comprehensively, and then all-direction ground surface settlement information is obtained.

Description

A Shallow Tunnel Pipe Curtain Stress Monitoring System Technical Field

[0001] This utility model relates to the field of tunnel engineering construction technology, specifically a stress monitoring system for shallow buried tunnel pipe curtain. Background Technology

[0002] In the construction of shallow-buried tunnels in cities, when the overlying soil is disturbed, the soil within the disturbance area will experience settlement exceeding the allowable limits, threatening the normal operation of existing highways. Therefore, monitoring surface settlement parameters and controlling surface deformation has become a problem that must be solved in the construction of shallow-buried tunnels.

[0003] Chinese patent application number 202311360396.6, entitled "Surface Settlement Monitoring Device and Method," provides a surface settlement monitoring device and method. The device includes a filling layer, a support member, a protective cover, a monitoring unit, and an acquisition unit. The filling layer, support member, and monitoring units are connected sequentially, and all components, including the filling layer, support member, and some monitoring units, are installed within burial holes drilled in the ground surface. The protective cover is placed over the burial holes, with the monitoring units facing the protective cover. The monitoring units monitor the displacement of the support member and transmit the displacement to the acquisition unit. This surface settlement monitoring method can only sample certain locations on the ground surface for monitoring. The monitoring results are significantly affected by the selection of sampling points, making it impossible to obtain comprehensive surface settlement information. Furthermore, it presents significant challenges for subsequent construction. Summary of the Invention

[0004] This invention provides a shallow-buried tunnel pipe curtain stress monitoring system, which solves the problem of difficulty in sensing the pipe curtain stress in the CD method excavation section under an existing highway.

[0005] The present invention utilizes a pipe jacking system for stress monitoring. Pipe jacking, as one of the most effective means of controlling surface deformation, is frequently used in projects with high quality requirements. After the pipe jacking is installed, the overlying soil of the tunnel is subjected to the superposition of its own weight and other vibration loads, which exert forces on the pipe jacking structure. The internal deformation of the overlying soil has a linear correlation with the deformation of the pipe jacking. Therefore, monitoring the stress state of the pipe jacking can indirectly reflect the safety status of the overlying soil of the tunnel.

[0006] The technical solution of this utility model is as follows:

[0007] A shallow-buried tunnel pipe curtain stress monitoring system includes an arc-shaped pipe curtain installed below the overburden layer. The arc-shaped pipe curtain is composed of several steel pipes arranged side by side, with the length direction of the steel pipes along the tunnel's travel direction. The outline of the arc-shaped pipe curtain coincides with the tunnel's arch. Several vibrating wire stress sensors are arranged along the length direction of each steel pipe. The vibrating wire stress sensors are installed between a mounting bracket and an arc-shaped clip, with the mounting bracket welded to the top of the steel pipe. The signal lines of the vibrating wire stress sensors are electrically connected to an external signal acquisition device.

[0008] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, a wedge-shaped protective shell is installed above the vibrating wire stress sensor, and a wiring hole is provided at the tail end of the wedge-shaped protective shell, through which the signal line of the vibrating wire stress sensor passes.

[0009] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, adjacent steel pipes are connected by male and female couplings.

[0010] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, a cable management groove is welded to the upper part of the female buckle. A cable routing hole is set at the position corresponding to the cable routing hole, and the signal line enters the cable management groove through the cable routing hole.

[0011] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, vibrating wire stress sensors are arranged at equal intervals on the steel pipe, with an arrangement spacing of 3m.

[0012] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, the vibrating wire stress sensor is arranged at the outer normal direction of the center contour line of the arc-shaped pipe curtain.

[0013] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, the signal acquisition device is electrically connected to the data terminal and the early warning system.

[0014] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, the steel pipe has a diameter of 402mm and a length of 6m.

[0015] In the aforementioned shallow-buried tunnel pipe curtain stress monitoring system, the wedge-shaped protective shell is welded onto the steel pipe.

[0016] This utility model has the following advantages compared with the prior art:

[0017] 1. This utility model indirectly reflects the safety status of the overlying soil layer of shallow-buried tunnels by monitoring the stress state of the tunnel duct curtain. Compared with traditional surface settlement monitoring, it has a higher monitoring frequency, does not require road space, and can ensure the normal operation of existing highways.

[0018] 2. This utility model forms an array-type monitoring system that surrounds the entire pipe curtain by arranging sensors at equal intervals on each pipe curtain, thus comprehensively sensing the stress state of the pipe curtain and obtaining comprehensive information on ground subsidence.

[0019] 3. This utility model arranges a wedge-shaped protective shell above the vibrating wire stress sensor and protects the sensor signal line with a cable management groove, which effectively improves the survival rate of the sensor during the monitoring process and improves the reliability of the system.

[0020] 4. This utility model collects data via a data acquisition device and uploads it to a data terminal. The monitoring frequency is 5 minutes per time. The data terminal is connected to an early warning system, which can draw a three-dimensional stress state curve of the pipe jacking in real time, set early warning values, and analyze the stress state of the pipe jacking in real time. By locating the early warning measurement points, safety hazards can be addressed in a timely manner, ensuring the safe operation of existing highways and tunnels. Attached Figure Description

[0021] Figure 1 is a schematic diagram of the monitoring principle of this utility model;

[0022] Figure 2 is a schematic diagram of the sensor and fixing device of this utility model;

[0023] Figure 3 is a schematic diagram of the wedge-shaped protective shell structure of this utility model;

[0024] Figure 4 is a schematic diagram of the sensor and wedge-shaped protective shell assembly of this utility model;

[0025] Figure 5 is a schematic diagram of the cable management groove structure of this utility model;

[0026] Figure 6 is a schematic diagram of the sensor and wiring method of this utility model;

[0027] Figure 7 shows typical test results of this utility model.

[0028] The attached diagram is labeled as follows: 1-steel pipe; 2-vibrating wire stress sensor; 3-clip seat; 4-pin; 5-screw fixing hole; 6-screw; 7-wedge-shaped protective shell; 8-baffle; 9-wiring hole; 10-signal line; 11-line hole; 12-cable groove; 13-signal acquisition device; 14-data terminal; 15-early warning system; 21-tunnel overburden layer; 22-tunnel initial support; 23-arc-shaped buckle; 24-male buckle; 25-female buckle; 26-arc-shaped pipe curtain. Detailed Implementation

[0029] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0030] Pipe jacking is a commonly used form of advanced support in tunnel construction. It is a key technology for the unearthed excavation of tunnels or large underground structures in areas with weak strata, shallow buried sections, or areas with extremely high requirements for surface settlement control (such as under densely built-up urban areas). It consists of multiple large-diameter steel pipes or concrete pipes that are horizontally jacked along the outside of the tunnel or underground structure excavation outline. By forming an advanced support shell before excavation, it can withstand external earth pressure and water pressure, thereby controlling surface settlement, preventing excavation face collapse, reducing disturbance to the surrounding environment, and protecting adjacent buildings and structures.

[0031] Referring to Figures 1 to 6, the shallow-buried tunnel pipe curtain stress monitoring system of this utility model includes an arc-shaped pipe curtain 26 installed below the overburden layer. The arc-shaped pipe curtain 26 is composed of several steel pipes 1 arranged side by side, with the length direction of the steel pipes 1 along the tunnel's passage direction, and the outline of the arc-shaped pipe curtain aligning with the tunnel's arch. Several vibrating wire stress sensors 2 are arranged along the length direction of each steel pipe 1. The vibrating wire stress sensors 2 are installed between a mounting base 3 and an arc-shaped buckle 23, with the mounting base 3 welded to the top of the steel pipe 1. The signal line 10 of the vibrating wire stress sensor 2 is electrically connected to an external signal acquisition device 13. The signal acquisition device 13 sends real-time monitoring data to a data terminal 14, which is connected to an early warning system 15. The function of the data transmission terminal 13 is to store the data collected by the signal acquisition device 13 and transmit it to the early warning system 15 in real time according to the monitoring frequency. The early warning system 15 can plot a three-dimensional stress curve based on the real-time data, set stress early warning values, and provide early warnings and location information for points exceeding limits.

[0032] In Figure 1, the lower edge of the initial support 22 of the tunnel forms the tunnel's arched roof. The curvature of the arched pipe curtain 26 matches the arched roof of the tunnel. In practice, the center of each steel pipe is equidistant from the upper edge of the tunnel's arched roof. Therefore, the line connecting the center points of the cross-sections of each steel pipe also forms an arc-shaped contour line that matches the tunnel's arched roof. The vibrating wire stress sensor 2 is arranged at the outer normal direction of the center contour line of the arched pipe curtain 26. This sensor arrangement can improve the monitoring effect of the vibrating wire stress sensor, allowing for comprehensive perception of the pipe curtain's stress state, meeting the needs of pipe curtain stress monitoring in the CD method excavation section of the tunnel, and improving the safety control level of the support structure.

[0033] Referring to Figure 2, the vibrating wire stress sensor 2 includes a tube body, a sensitive element, and a signal line 10. The tube body is welded and fixed to the outer surface of the tube curtain by a locking device, which is composed of a retainer 3 and an arc-shaped buckle 23. A screw fixing hole 5 is provided on the right edge of the buckle, and the upper and lower parts of the buckle are fixed by screws 6. The retainer 3 is welded to the outer surface of the rigid tube. For easy disassembly and assembly, the left side of the buckle can also be designed with a movable structure, such as using a pin 4 to fix it to a conventional boss. In use, the arc-shaped buckle 23 can be opened at a certain angle around the left pin 4. After the sensor tube body is installed, it is then fixed by screws.

[0034] As shown in Figures 3 and 4, a wedge-shaped protective shell 7 is provided above the vibrating wire stress sensor 2. A wiring hole 9 is provided at the tail end of the wedge-shaped protective shell 7, through which the signal line 10 of the vibrating wire stress sensor 2 passes. The wedge-shaped protective shell is made of stainless steel, and its function is to protect the vibrating wire strain sensor during the pipe curtain jacking process, thereby improving the sensor survival rate and the reliability of the system.

[0035] As shown in Figures 5 and 6, the vibrating wire stress sensors 2 are arranged at equal intervals on the steel pipes 1, with a spacing of 2-3m. Adjacent steel pipes 1 are movably connected by male and female couplings 24 and 25. A cable management groove 12 is welded to the upper part of the female coupling 25. A cable guiding hole 11 is provided at the position corresponding to the cable routing hole 9 in the cable management groove 12. The signal line 10 enters the cable management groove 12 through the cable guiding hole 11. Depending on the construction conditions, the signal line passing through the cable routing hole 9 to the cable management groove 12 can be protected by using the processing waste of locking angle steel. The cable tension and wear caused by the deformation of the steel pipe under stress can be overcome by bending or reserving a certain length inside the cable management groove 12. This is a conventional method in tunnel construction and will not be described in detail here.

[0036] In this embodiment, the steel pipes of the pipe curtain have a diameter of approximately 402mm, a wall thickness of 10mm, and a single length of 6m, welded at the joints to form a continuous pipe curtain. Due to its sufficient rigidity, it is not easily affected by external vibrations, thus minimizing interference with sensor measurements. In other words, by measuring the deformation of the pipe curtain, the deformation of the overburden layer at the corresponding point can be represented. The wedge-shaped protective shell measures 300mm × 46mm × 50mm and weighs approximately 1.6kg, a very small proportion compared to the steel pipe. It is fixed to a designated position on the steel pipe with screws or welded to it. The added weight of the wedge-shaped protective shell compared to the large steel pipe does not affect the test or the system's stability. Furthermore, the wedge-shaped protective shell is separate from the stress sensor; even with added weight, it does not affect signal testing. The male and female fasteners 24 and 25 are commonly used accessories in pipe curtain construction and will not be described in detail here.

[0037] The hardware installation steps for the above-mentioned shallow-buried tunnel pipe jacking stress monitoring system are as follows:

[0038] Step 1: Determine the tangent direction of the pipe curtain center on the overall outer contour line according to the pipe curtain construction drawings, and use the position of the male and female buckles of the pipe curtain as a reference to determine the installation position of the sensor.

[0039] Step 2: Based on the sensor installation positions determined in Step 1, weld the vibrating wire stress sensor to the outer surface of the pipe curtain, with an installation spacing of 3m. After passing the sensor signal wire through the wiring hole of the wedge-shaped protective shell, weld the protective shell.

[0040] Step 3: Gather the sensor signal lines of each pipe curtain to the edge of the female buckle and weld the cable management groove.

[0041] As shown in Figure 7, a typical measuring point of the pipe jacking was selected for analysis. The longitudinal position of this measuring point is located at the midpoint of the total length of the pipe jacking, and the circumferential position is located at the left arch waist of the tunnel. The monitoring results can reflect the longitudinal stress change trend of the outer structure of the pipe jacking. By judging the safety status of the pipe jacking structure, the safety status of the overlying soil of the tunnel can be obtained.

[0042] This utility model's shallow-buried tunnel pipe liner stress monitoring system can indirectly reflect the safety status of the overlying soil layer, i.e., the existing highway. As the most effective means of controlling surface deformation, ensuring the pipe liner itself is in a safe state guarantees the safe operation of the highway above the tunnel. Therefore, deploying a stress monitoring system on the outside of the pipe liner to comprehensively monitor its stress state effectively and efficiently achieves this goal. Technical personnel can obtain stress history curves at any measuring point on the pipe liner at any time, set safety warning values, effectively ensure the safety of construction personnel and the operational safety of the existing highway, accurately locate warning measuring points, and provide technical personnel with sufficient time to take relevant measures.

Claims

1. A shallow-buried tunnel pipe curtain stress monitoring system, comprising an arc-shaped pipe curtain (26) installed below the overburden layer, wherein the arc-shaped pipe curtain (26) is composed of several steel pipes (1) arranged side by side, the length direction of the steel pipes (1) being along the tunnel's passage direction, and the outline of the arc-shaped pipe curtain being consistent with the tunnel's arch; characterized in that: Several vibrating wire stress sensors (2) are arranged along the length of each steel pipe (1). The vibrating wire stress sensors (2) are installed between the card holder (3) and the arc-shaped buckle (23). The card holder (3) is welded to the top of the steel pipe (1). The signal line (10) of the vibrating wire stress sensor (2) is electrically connected to the external signal acquisition device (13).

2. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: A wedge-shaped protective shell (7) is provided above the vibrating wire stress sensor (2), and a wiring hole (9) is provided at the tail end of the wedge-shaped protective shell (7). The signal line (10) of the vibrating wire stress sensor (2) passes through the wiring hole (9).

3. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: Adjacent steel pipes (1) are connected by male and female couplings (24 and 25).

4. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: The upper part of the female buckle (25) is welded with a cable management groove (12). The cable management groove (12) and the cable routing hole (9) are provided with a cable guiding hole (11). The signal line (10) enters the cable management groove (12) through the cable guiding hole (11).

5. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: Vibrating wire stress sensors (2) are arranged at equal intervals on the steel pipe (1), with a spacing of 2-3m.

6. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 5, characterized in that: The angle at which the vibrating wire stress sensor (2) is arranged is the outer normal direction of the center contour line of the arc-shaped pipe curtain (26).

7. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: The signal acquisition device (13) is electrically connected to the data terminal (14) and the early warning system (15).

8. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: The diameter of the steel pipe (1) is 402mm and the length is 6m.

9. The shallow-buried tunnel pipe curtain stress monitoring system according to claim 1, characterized in that: The wedge-shaped protective shell (7) is welded onto the steel pipe.

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