Shield tunnel model test stratum deformation measuring device and measuring method

Abstract

This invention discloses a measurement device and method for measuring ground deformation in a shield tunnel model test, belonging to the technical field of shield tunnel model testing. The measurement device includes a distributed fiber optic sensor, guide rod pads, displacement guide rods, differential displacement gauges, and gauge bases. Both ends of the distributed fiber optic sensor are connected to two guide rod pads, one end of each of the two displacement guide rods is connected to one guide rod pad, and the other end of each displacement guide rod is connected to the pointers of two differential displacement gauges. The two differential displacement gauges are mounted on two gauge bases. The measurement method includes: filling the model box with soil and installing the measurement device for ground deformation in the shield tunnel model test; and calculating the ground deformation using a matrix. This invention can achieve deformation measurement at multiple locations within the ground, and the measured data has the advantages of continuity and long-distance measurement, providing complete ground deformation characteristics for analyzing the interaction mechanism between the shield tunnel structure and the ground.

Description

Technical Field

[0001] This invention belongs to the field of shield tunnel model testing technology, specifically relating to a measuring device and method for measuring ground deformation in shield tunnel model testing. Background Technology

[0002] Large cross-sections and complex engineering conditions have become the current development trend of shield tunnels. The structural analysis and design methods based on small and medium cross-section shield tunnels in the past are difficult to adapt to the structural mechanical performance problems of large cross-section shield tunnels under complex engineering conditions. Therefore, it is urgent to explore the structural mechanical performance laws of large cross-section shield tunnels and establish analytical methods that can fully consider the structural characteristics of large cross-section shield tunnels.

[0003] In the study of the mechanical properties of shield tunnel structures, similar model tests are a highly effective research method in tunnel research because they allow for the acquisition of mechanical laws governing tunnel structures and provide a direct view of failure modes while controlling experimental costs. The focus of large-section shield tunnel model tests is on the interaction mechanism between the tunnel structure and the strata under load. However, in past studies, limited by testing methods, researchers have typically focused on the deformation or strain of the tunnel structure, paying less attention to the deformation state of the strata. Therefore, to further analyze the mechanical properties of large-section shield tunnels and the interaction mechanism between the structure and the strata, it is necessary to design a measurement device and method for strata deformation.

[0004] Currently, traditional methods for measuring ground deformation in shield tunnel model tests have shortcomings. For example, invention application No. "201510748018.4" discloses an experimental device for measuring the deformation and strain of ground near shield tunnel construction. The device includes a box-shaped structure with at least two transparent sides. Two opposite sides of the box have through holes. A steel block is mounted on one side of the box, with one through hole having a larger diameter than the other. The box also has a first steel pipe passing through the two through holes and a second steel pipe passing through the larger diameter through hole. The second steel pipe is located outside the first steel pipe and is movably connected to it. The steel block has a hollow internal structure, with a movable block movably connected inside. A camera is mounted outside the box. This invention uses experimental equipment to simulate the shield tunnel construction process, uses the camera to photograph the cross-section of the entire tunnel and the longitudinal section of half the tunnel, and uses image processing technology to calculate and analyze ground deformation.

[0005] The aforementioned invention application utilizes a camera to capture images of geological changes and then uses image processing technology to calculate and analyze geological deformation. However, the camera cannot capture internal geological changes and cannot measure deformation at different locations within the geological strata. The measurement locations are very limited and cannot meet the needs of practical applications. Summary of the Invention

[0006] The purpose of this invention is to provide a measuring device and method for measuring the deformation of the strata in a shield tunnel model test with comprehensive measurement capabilities, in order to solve the above-mentioned problems.

[0007] The present invention achieves the above objectives through the following technical solutions:

[0008] A measuring device for ground deformation in a shield tunnel model test includes a distributed optical fiber sensor, guide rod pads, displacement guide rods, differential displacement gauges, and gauge bases. The two ends of the distributed optical fiber sensor are respectively connected to two of the guide rod pads. One end of each of the two displacement guide rods is connected to one of the two guide rod pads, and the other end of each of the two displacement guide rods is connected to the pointers of the two differential displacement gauges. The two differential displacement gauges are respectively mounted on two gauge bases.

[0009] Preferably, to facilitate installation and improve deformation synchronization between the distributed optical fiber sensor and the soil, the shield tunnel model test stratum deformation measuring device further includes a model box. The model box has protruding mounting portions on its opposite side walls. Two gauge mounts are respectively installed on the two mounting portions. The distributed optical fiber sensor is fixedly connected to a strip of geotextile via silicone rubber to form a strip-shaped sensor assembly. The two ends of the distributed optical fiber sensor are recessed compared to the two ends of the geotextile. Two guide rod pads are respectively bonded to the two ends of the geotextile. The two guide rod pads are respectively welded to the lower ends of two vertical displacement guide rods. The pointers of the two differential displacement gauges are respectively connected to the upper ends of the two displacement guide rods. The two displacement guide rods, the two guide rod pads, and the sensor assembly are all located inside the model box, with the two displacement guide rods close to their corresponding mounting portions.

[0010] Preferably, in order to prevent the soil from affecting the free movement of the displacement guide rods, the measuring device for the stratum deformation of the shield tunnel model test also includes a sleeve, with the two displacement guide rods passing through the central through holes of the two vertical sleeves respectively, and a gap being left between the inner wall of the sleeve and the outer wall of the displacement guide rod.

[0011] Preferably, for easy and quick installation, the base is a magnetic base and is installed on the corresponding mounting part by magnetic force.

[0012] A method for measuring ground deformation in a shield tunnel model test includes the following steps:

[0013] Step 1: Fill the model box with soil. Once the soil level reaches the height corresponding to the required detection location, install the shield tunnel model test stratum deformation measuring device on top of the soil. Connect the distributed fiber optic sensor to the control device outside the model box via wires. After installation, continue filling with soil until the design height is reached. Then, apply pressure to the soil using a pressurizing device to form a stratum. The control device here can be a microcontroller, processor, electrical control box, etc., as long as it contains a microprocessor chip and has signal processing capabilities.

[0014] Step 2: Calculate the formation deformation using the following matrix:

[0015]

[0016] Among them, y1, y2…y n These are the displacement values ​​of a cross section corresponding to a certain detection point on the sensor assembly and the distributed optical fiber sensor, respectively, obtained by the distributed optical fiber sensor, where y0 and y... n+1 The displacement values ​​at both ends of the geotextile are obtained by differential displacement gauges, n is the number of detection points on the distributed fiber optic sensor, h is the thickness of the geotextile, z is the spatial resolution of the distributed fiber optic sensor, and ε1, ε2, ε3…ε n These are the formation strains corresponding to a specific detection point on the distributed optical fiber sensor.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention places distributed optical fiber sensors within the soil of the stratum. Multiple detection points on the distributed optical fiber sensors can detect displacement at corresponding locations within the soil. The displacement at both ends of the distributed optical fiber sensors is transmitted to a differential displacement gauge via guide rod pads and displacement guide rods. Finally, the strain of the stratum deformation in the shield tunnel model test is obtained through matrix calculation. This invention enables deformation measurement at multiple locations within the stratum, providing comprehensive measurement coverage. Furthermore, the measured data has the advantages of continuity and long-distance measurement, providing complete stratum deformation characteristics for analyzing the interaction mechanism between the shield tunnel structure and the stratum. The manufacturing method is simple, allowing for the rapid fabrication of multiple measuring devices with convenient arrangement, significantly reducing the setup time of experimental components and saving experimental time costs. With slight modifications to the manufacturing materials, this invention can be extended to practical engineering applications for health monitoring of underground structures such as tunnels. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of the measuring device for ground deformation in the shield tunnel model test according to the present invention;

[0020] Figure 2This is a radial cross-sectional view of the sensor assembly of the measuring device for ground deformation in the shield tunnel model test according to the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings:

[0022] like Figure 1 and Figure 2 As shown, the measuring device for stratum deformation in the shield tunnel model test of the present invention includes a distributed optical fiber sensor 82, guide rod pads 7, displacement guide rods 5, differential displacement gauges 4, and gauge bases 3. The two ends of the distributed optical fiber sensor 82 are respectively connected to two guide rod pads 7, one end of the two displacement guide rods 5 is respectively connected to two guide rod pads 7, and the other end of the two displacement guide rods 5 is respectively connected to the pointers of the two differential displacement gauges 4. The two differential displacement gauges 4 are respectively mounted on two gauge bases 3.

[0023] Preferably, to facilitate installation and improve deformation synchronization between the distributed optical fiber sensor 82 and the soil, the shield tunnel model test stratum deformation measuring device further includes a model box 1. The model box 1 has protruding mounting portions 2 on its opposite side walls (more mounting portions 2 can be provided depending on application needs). Two gauge bases 3 are respectively mounted on the two mounting portions 2. The distributed optical fiber sensor 82 is fixedly connected to the strip geotextile 83 via silicone rubber 81 to form a strip-shaped sensor assembly 8. The two ends of the distributed optical fiber sensor 82 are recessed compared to the two ends of the geotextile 83. Two guide rod pads 7 are respectively bonded to the two ends of the geotextile 83. The gaskets 7 are welded to the lower ends of the two vertical displacement guide rods 5 respectively, and the pointers of the two differential displacement gauges 4 are connected to the upper ends of the two displacement guide rods 5 respectively. The two displacement guide rods 5, the two guide rod gaskets 7 and the sensor assembly 8 are all located inside the model box 1, and the two displacement guide rods 5 are close to the corresponding mounting parts 2 respectively. In order to prevent the soil from affecting the free movement of the displacement guide rods 5, the measuring device for the stratum deformation of the shield tunnel model test also includes a sleeve 6. The two displacement guide rods 5 pass through the central through holes of the two vertical sleeves 6 respectively, and a gap is left between the inner wall of the sleeve 6 and the outer wall of the displacement guide rod 5. In order to facilitate quick installation, the base 3 is a magnetic base and is installed on the corresponding mounting part 2 by magnetic force.

[0024] The specific manufacturing method of the aforementioned sensor component 8 is as follows: First, straighten the distributed optical fiber sensor 82 and the geotextile 83. The two ends of the distributed optical fiber sensor 82 are slightly recessed compared to the two ends of the geotextile 83. Place the distributed optical fiber sensor 82 in the center of the surface of the geotextile 83 and ensure they are tightly bonded. Use silicone rubber 81 to bond the contact surfaces of the distributed optical fiber sensor 82 and the geotextile 83. Simultaneously, continue to apply silicone rubber 81 above the distributed optical fiber sensor 82 to form a certain thickness, which protects the distributed optical fiber sensor 82. Figure 2 As shown, this process can increase the friction between the distributed optical fiber processor 82 and the soil in the stratum, thereby improving the deformation synchronization between the two.

[0025] Figure 1 Also shown is the shield segment test piece 9 set inside the model box 1, which is used to simulate the tunnel assembled from shield segments in a shield tunnel. This is a conventional test equipment.

[0026] Combination Figure 1 and Figure 2 The method for measuring ground deformation in a shield tunnel model test according to the present invention includes the following steps:

[0027] Step 1: Fill the model box 1 with soil (not shown in the figure). When the soil height reaches the height corresponding to the required detection position, install the shield tunnel model test stratum deformation measuring device on the soil. Connect the distributed fiber optic sensor 82 to the control device (not shown in the figure, a conventional device) outside the model box 1 through wires. After installation, continue filling the soil until the design height is reached. Then, pressurize the soil to the set pressure through a pressurizing device (not shown in the figure, a conventional pressurizing device, such as a hydraulic jack) to form a stratum (the stratum here is a test stratum used to simulate the real stratum).

[0028] Step 2: Calculate the formation deformation using the following matrix:

[0029]

[0030] Among them, y1, y2…y n These are the displacement values ​​of a certain section corresponding to a certain detection point on sensor assembly 8 and distributed optical fiber sensor 82, respectively, obtained by distributed optical fiber sensor 82, where y0 and y n+1 The displacement values ​​at both ends of the geotextile 83 are obtained by the differential displacement gauge 4, n is the number of detection points on the distributed optical fiber sensor 82, h is the thickness of the geotextile 83, z is the spatial resolution of the distributed optical fiber sensor 82, and ε1, ε2, ε3…ε n These are the formation strains corresponding to a certain detection point on the distributed optical fiber sensor 82.

[0031] The above matrix was obtained through the following reasoning:

[0032] The approximate differential equation of the deflection curve of sensor component 8 can be expressed as:

[0033]

[0034] Where E is the elastic modulus of geotextile 83, I is the moment of inertia of the cross section of geotextile 83, y(x) is the displacement value of a certain section corresponding to a certain detection point on sensor assembly 8 and distributed optical fiber sensor 82, obtained by distributed optical fiber sensor 82, y(x) is the second derivative of y(x), M is the bending moment of the corresponding section, and h is the thickness of geotextile 83.

[0035] From the above formula, we can obtain:

[0036]

[0037] From Taylor expansion, we get:

[0038]

[0039] In the formula, z is the spatial resolution of the distributed optical fiber sensor 82, and i is one of the n detection points of the distributed optical fiber sensor 82. Neglecting higher-order quantities, we can obtain:

[0040]

[0041] As can be seen from the formula, the deformation values ​​of the distributed optical fiber sensor 82 and the geotextile 82 are only related to the strain value of the distributed optical fiber sensor 82 at that location. Therefore, the displacement value can be calculated from the strain of the distributed optical fiber sensor 82 obtained by measurement using this formula. The above formula can also be expressed as n equations, as shown below:

[0042]

[0043] From the matrix representation, we can obtain:

[0044]

[0045] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of the patent of the present invention.

Claims

1. A measuring device for ground deformation in a shield tunnel model test, characterized in that: The device includes a distributed fiber optic sensor, guide rod pads, displacement guide rods, differential displacement gauges, and gauge bases. Both ends of the distributed fiber optic sensor are connected to two guide rod pads, one end of each displacement guide rod is connected to one guide rod pad, and the other end of each displacement guide rod is connected to the pointers of two differential displacement gauges. The two differential displacement gauges are mounted on two gauge bases. The shield tunnel model test ground deformation measuring device also includes a model housing. The opposite side walls of the model housing are provided with protruding mounting portions, and the two gauge bases are mounted on the two mounting portions. The distributed optical fiber sensor is fixedly connected to the strip geotextile with silicone rubber to form a strip-shaped sensor assembly. The two ends of the distributed optical fiber sensor are recessed compared to the two ends of the geotextile. The two guide rod pads are respectively bonded to the two ends of the geotextile. The two guide rod pads are respectively welded to the lower ends of the two vertical displacement guide rods. The pointers of the two differential displacement gauges are respectively connected to the upper ends of the two displacement guide rods. The two displacement guide rods, the two guide rod pads, and the sensor assembly are all located inside the model box. The two displacement guide rods are respectively close to the corresponding mounting parts.

2. The measuring device for ground deformation in a shield tunnel model test according to claim 1, characterized in that: The measuring device for ground deformation in the shield tunnel model test also includes a sleeve, with the two displacement guide rods passing through the central through holes of the two vertical sleeves respectively, and a gap being left between the inner wall of the sleeve and the outer wall of the displacement guide rod.

3. The measuring device for ground deformation in a shield tunnel model test according to claim 1 or 2, characterized in that: The base is a magnetic base and is magnetically mounted on the corresponding mounting part.

4. A method for measuring ground deformation in a shield tunnel model test, characterized in that: Includes the following steps: Step 1: Fill the model box with soil. When the soil height reaches the height corresponding to the required detection position, install the measuring device for the deformation of the stratum in the shield tunnel model test as described in claim 1 or 2 above the soil. Connect the distributed optical fiber sensor to the control device outside the model box through wires. After installation, continue to fill the soil until the design height is reached. Then, pressurize the soil to the set pressure through the pressurization device to form a stratum. Step 2: Calculate the formation deformation using the following matrix: ； in, y 1. y 2… y n These are the displacement values ​​of a certain cross-section corresponding to a certain detection point on the sensor assembly and the distributed optical fiber sensor, respectively, obtained by the distributed optical fiber sensor. y 0 and y n+1 The displacement values ​​at both ends of the geotextile are obtained using differential displacement gauges. n This represents the number of detection points on the distributed fiber optic sensor. h The thickness of the geotextile. z For the spatial resolution of distributed fiber optic sensors. ε 1. ε 2. ε 3… ε n These are the formation strains corresponding to a specific detection point on the distributed optical fiber sensor.

Images