A tunnel pipe support deformation measurement device and support effect evaluation method

Abstract

The present invention discloses a tunnel pipe-roof support deformation measurement device and a support effect evaluation method, which measures the deformation of the tunnel pipe-roof through a fiber grating strain sensor, and evaluates the support effect of the pipe-roof according to the deformation of the pipe-roof. The tunnel pipe-roof support effect evaluation method of the present invention can make up for the problems that the traditional method includes the evaluation of initial support when using clearance convergence as the evaluation index of the pipe-roof support effect, fails to evaluate the effect of the pipe-roof separately, and cannot evaluate whether the pipe-roof is overused. It can reflect the deformation process of the pipe-roof and evaluate the effect of the pipe-roof support separately, judge the effect of the pipe-roof as an advanced support in the surrounding rock, increase the feedback of the effect of the pipe-roof support, and provide reference for similar projects.

Description

Technical Field

[0001] The invention relates to the technical field of highway tunnel construction, and in particular to a tunnel pipe-roof support deformation measuring device and a support effect evaluation method. Background Art

[0002] The surrounding rock of the tunnel entrance is usually poor. To ensure construction safety, pipe sheds are usually used as supports for pre-reinforcement. Clearance convergence is usually used as an evaluation index for the effect of pipe shed support, but clearance convergence is an evaluation index for the safety of initial support under support. It evaluates the combined effect of pipe shed support and initial support, but fails to evaluate the effect of pipe shed alone. It is impossible to evaluate whether the pipe shed is overused, so it is impossible to optimize the pipe shed support parameters in the support. Summary of the invention

[0003] In view of the fact that the current evaluation method for the effect of pipe-roof support is unable to evaluate the effect of the pipe-roof alone, the present invention provides a method for measuring the deformation of the pipe-roof support during tunnel construction after the pipe-roof construction and a method for evaluating the effect of the pipe-roof support.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for evaluating the support effect of a pipe-roof support comprises the following steps:

[0006] Step 1: After the pipe shed support construction is completed, the initial position of each monitoring point on the arch steel pipe is obtained;

[0007] Step 2, obtaining the first position of each monitoring point when the tunnel is excavated to each monitoring point of the arch steel pipe;

[0008] Step 3: When the tunnel excavation length exceeds the set distance from each monitoring point of the arch steel pipe, the second position of each monitoring point is obtained;

[0009] Step 4, obtaining the initial support vault settlement of the corresponding section of each monitoring point of the vault steel pipe after tunnel excavation;

[0010] Step 5: Determine the internal vertical deformation of the surrounding rock at each monitoring point according to the initial position and the first position of each monitoring point;

[0011] Step 6: Determine the vertical deformation of the arch steel pipe at each monitoring point according to the initial position and the second position of each monitoring point;

[0012] Step 7: Determine the pipe-roof support effect value of the section corresponding to the monitoring point based on the initial support arch settlement, the vertical deformation inside the surrounding rock, and the vertical deformation of the arch steel pipe in the section corresponding to the monitoring point, and evaluate the support effect of the pipe-roof support based on the pipe-roof support effect value.

[0013] Preferably, in step 1, a plurality of monitoring points are equidistantly arranged along the axial direction of the arch steel pipe, and a displacement monitoring device is arranged at each monitoring point.

[0014] Preferably, the displacement monitoring device is a fiber grating strain sensor.

[0015] Preferably, the monitoring point in step 1 is set on the arch steel pipe at the center of the tunnel arch.

[0016] Preferably, in step 5, the vertical deformation inside the surrounding rock is determined based on the difference between the initial position and the first position.

[0017] Preferably, in step 6, the vertical deformation of the arch steel pipe is determined according to the difference between the initial position and the second position.

[0018] Preferably, in step 7, the mean value of the pipe-roof support effect value of each monitoring point is calculated, and the support effect of the pipe-roof support is evaluated based on the mean value of the pipe-roof support effect.

[0019] Preferably, the calculation method of the pipe-roof support effect value is as follows:

[0020] wi=xi / (yi+zi)×100%

[0021] Among them, xi is the vertical deformation of the surrounding rock corresponding to the ith monitoring point, yi is the vertical deformation of the steel pipe corresponding to the ith monitoring point, and zi is the initial support arch settlement corresponding to the ith monitoring point.

[0022] Preferably, step 7 also includes the following process, optimizing the structure of the pipe-roof support according to the support effect.

[0023] A pipe-roof support deformation measuring device for a pipe-roof support support effect evaluation method comprises a vault steel pipe and a plurality of fiber grating strain sensors equidistantly arranged along its axial direction, wherein the fiber grating strain sensors are attached to the outer wall of the vault steel pipe, and the vault steel pipe is located at the top of the center of the tunnel vault.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] The present invention provides a method for evaluating the support effect of pipe-roof support, in which multiple monitoring points are set on the arch steel pipe, and the vertical deformation of the initial support arch settlement, the vertical deformation inside the surrounding rock and the vertical deformation of the steel pipe of the section corresponding to each monitoring point are obtained, and then the pipe-roof support effect value of the section corresponding to the monitoring point is obtained, and the support effect of the pipe-roof support is evaluated according to the pipe-roof support effect value, which can make up for the traditional method of using clearance convergence as the pipe-roof support effect evaluation index, and the evaluation index includes the evaluation of the initial support, so it is impossible to objectively evaluate the effect of the pipe-roof, and thus the optimization basis of the pipe-roof support cannot be provided. The evaluation method of the present invention measures the deformation process of the pipe-roof to achieve the evaluation of the effect of the pipe-roof support, judges the effect of the pipe-roof as an advanced support in the surrounding rock, increases the feedback of the effect of the pipe-roof support, and provides an optimization basis for the pipe-roof support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a front view of the tunnel pipe roof arrangement of the present invention.

[0027] Figure 2 It is a side view of the tunnel pipe roof arrangement of the present invention.

[0028] Figure 3 Layout diagram of fiber Bragg grating strain sensor.

[0029] In the figure: 1-arch, 2-tunnel outline, 3-tunnel entrance, 4-tunnel face, 5-arch steel pipe, 6-first monitoring point, 7-monitoring point, 8-fiber Bragg grating strain sensor, 9-initial support monitoring point. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0031] See also Figure 1-3 A method for evaluating the support effect of a pipe-roof support comprises the following steps:

[0032] Step 1: After the pipe-roof support construction is completed, the initial position of each monitoring point 7 on the arch steel pipe 5 is obtained.

[0033] Specifically, pipe-roof support is a type of tunnel support, generally used for supporting the tunnel portal 3, to avoid collapse accidents caused by weak surrounding rock during tunnel excavation, and to effectively improve the safety of construction. The pipe-roof support is composed of a plurality of parallel arch steel pipes, an arch sleeve 1 is set at the arch of the tunnel portal, the arch steel pipe passes through the arch sleeve 1 and is inserted into the rock mass of the tunnel arch along the tunnel excavation direction, and a plurality of arch steel pipes are arranged in parallel at intervals along the cross-sectional shape of the tunnel arch. Since the length of the arch steel pipe is relatively long, the length of the arch steel pipe is generally greater than 40m, so a plurality of monitoring points are set on the arch steel pipe along its axial direction, and a fiber grating strain sensor 8 is set at each monitoring point and numbered, A0, A1, ...An. A plurality of deformation monitoring points are arranged at equal intervals, and the first monitoring point 6 is at a certain distance from the tunnel portal. The arch steel pipe with a measuring device is inserted into the rock mass of the tunnel along the tunnel excavation method and is located above the tunnel arch.

[0034] The top of the tunnel profile 2 is an arc-shaped vault structure, so the area with the maximum tunnel deformation is the center of the tunnel vault. Therefore, the vault steel pipe with the fiber grating strain sensor 8 is set on the top of the center of the tunnel vault, and the initial position a0, a1, ...an of each monitoring point is obtained.

[0035] In this embodiment, a plurality of monitoring points are equidistantly arranged on the arch steel pipe, and the distance between adjacent monitoring points is less than or equal to 5 times the diameter of the steel pipe.

[0036] Step 2: Obtain the first position b0, b1, ...bn of each monitoring point when the tunnel is excavated to each monitoring point of the arch steel pipe.

[0037] Specifically, when tunnel excavation construction is carried out, excavation construction is carried out from the tunnel portal 3. When the tunnel face 4 (monitoring section) and the monitoring point are located in a vertical plane, the position of the monitoring point corresponding to the arch steel pipe is obtained.

[0038] Step 3: When the tunnel excavation length exceeds the set distance from each monitoring point of the arch steel pipe, the second position c0, c1, ...cn of each monitoring point is obtained;

[0039] Specifically, during the tunnel construction process, the pipe-roof support effect of the section corresponding to each monitoring point changes dynamically. The change is more significant when the excavation section is located within 1 times the tunnel diameter before the monitoring section and behind the monitoring section. Therefore, after the tunnel length exceeds the monitoring point setting, the position of the monitoring point is obtained.

[0040] For example, the distance between the first monitoring point and the tunnel entrance is 10m. When the tunnel is excavated to 10m, the first position of the first monitoring point is obtained, and the distance is set to 8m. When the tunnel is excavated to 18m, that is, it exceeds the first monitoring point to the set distance, the second position of the first monitoring point is obtained. The second position of each monitoring point is obtained according to this method.

[0041] Step 4, obtaining the vault settlement z0, z1, ... zn of the initial support monitoring points of the corresponding sections of each monitoring point of the vault steel pipe after tunnel excavation;

[0042] The monitoring points of the arch steel pipe and the initial support monitoring points 9 are located in the same section of the tunnel and have the same number.

[0043] Step 5: According to the difference between the initial position and the first position of each monitoring point of the arch steel pipe, the internal vertical deformation x0, x1, ..., xn of the surrounding rock of each monitoring point of the arch steel pipe is obtained.

[0044] Step 6: According to the difference between the initial position and the second position of each monitoring point of the arch steel pipe, the vertical deformation y0, y1, ...yn of each monitoring point of the arch steel pipe is obtained.

[0045] Step 7: According to the vault settlement, the vertical deformation of the surrounding rock and the vertical deformation of the steel pipe at the section corresponding to the monitoring point, the pipe-roof support effect value wi of the section corresponding to the monitoring point is determined. The calculation method is as follows:

[0046] wi=xi / (yi+zi)×100%

[0047] Among them, xi is the vertical deformation of the surrounding rock corresponding to the ith monitoring point, yi is the vertical deformation of the steel pipe corresponding to the ith monitoring point, and zi is the initial support arch settlement corresponding to the ith monitoring point.

[0048] Step 8: Calculate the mean value of the pipe-roof support effect value of each monitoring point, evaluate the support effect of the pipe-roof support based on the obtained mean value of the pipe-roof support effect, and optimize the structure of the pipe-roof support based on the support effect.

[0049] Specifically, the pipe-roof support effect values ​​of each monitoring point are added and averaged to obtain the mean value of the pipe-roof support effect. The mean value of the pipe-roof support effect is compared with the preset evaluation value. When the mean value of the pipe-roof support effect is greater than the preset evaluation value, the pipe-roof support plays a supporting role. When the mean value of the pipe-roof support effect is less than the preset evaluation value, the support effect of the pipe-roof support is poor, and the structure of the pipe-roof support needs to be optimized.

[0050] The larger the mean value of the pipe-roof support effect, the better the support effect. The smaller the mean value of the pipe-roof support effect, the less effective the arch steel pipe is. This indicates that the support is excessive and the structure of the pipe-roof support needs to be modified, such as increasing the spacing between the arch steel pipes and reducing the diameter of the arch steel pipes.

[0051] A device for measuring deformation of pipe-roof support comprises a vault steel pipe and a plurality of fiber grating strain sensors equidistantly arranged along its axial direction. The fiber grating strain sensors are attached to the outer wall of the vault steel pipe, which is located at the top of the tunnel vault center of the tunnel.

[0052] The present invention discloses a tunnel pipe-roof support deformation measurement device and a support effect evaluation method, which measures the deformation of the tunnel pipe-roof by using a fiber grating strain sensor, and evaluates the support effect of the pipe-roof according to the deformation of the pipe-roof. The tunnel pipe-roof support effect evaluation method of the present invention can make up for the problem that the traditional method includes the evaluation of initial support when using clearance convergence as the evaluation index of the pipe-roof support effect, and cannot evaluate the effect of the pipe-roof alone and cannot evaluate whether the pipe-roof is overused. The method evaluates the effect of the pipe-roof support alone according to the deformation process of the pipe-roof, judges the effect of the pipe-roof as support in the surrounding rock, increases the feedback of the effect of the pipe-roof support, and serves as the optimization basis of the pipe-roof support structure, providing a reference for similar projects.

[0053] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for evaluating the support effect of pipe-roof support, characterized in that: The following steps are involved: Step 1: After the pipe shed support construction is completed, the initial position of each monitoring point on the arch steel pipe is obtained; Step 2, obtaining the first position of each monitoring point when the tunnel is excavated to each monitoring point of the arch steel pipe; Step 3: When the tunnel excavation length exceeds the set distance from each monitoring point of the arch steel pipe, the second position of each monitoring point is obtained; Step 4, obtaining the initial support vault settlement of the corresponding section of each monitoring point of the vault steel pipe after tunnel excavation; Step 5: Determine the internal vertical deformation of the surrounding rock at each monitoring point according to the initial position and the first position of each monitoring point; Step 6: Determine the vertical deformation of the arch steel pipe at each monitoring point according to the initial position and the second position of each monitoring point; Step 7: Determine the pipe-roof support effect value of the section corresponding to the monitoring point based on the initial support arch settlement, the vertical deformation inside the surrounding rock, and the vertical deformation of the arch steel pipe in the section corresponding to the monitoring point, and evaluate the support effect of the pipe-roof support based on the pipe-roof support effect value.

2. A method for evaluating the support effect of pipe-roof support according to claim 1, characterized in that: In step 1, a plurality of monitoring points are equidistantly arranged along the axial direction of the arch steel pipe, and a displacement monitoring device is arranged at each monitoring point.

3. A method for evaluating the support effect of pipe-roof support according to claim 2, characterized in that: The displacement monitoring device is a fiber grating strain sensor.

4. A method for evaluating the support effect of pipe-roof support according to claim 1, characterized in that: The monitoring point described in step 1 is set on the arch steel pipe at the center of the tunnel arch.

5. A method for evaluating the support effect of pipe-roof support according to claim 1, characterized in that: In step 5, the vertical deformation inside the surrounding rock is determined based on the difference between the initial position and the first position.

6. A method for evaluating the support effect of pipe-roof support according to claim 1, characterized in that: In step 6, the vertical deformation of the arch steel pipe is determined according to the difference between the initial position and the second position.

7. A method for evaluating the support effect of pipe-roof support according to claim 1, characterized in that: In step 7, the mean value of the pipe-roof support effect value of each monitoring point is calculated, and the support effect of the pipe-roof support is evaluated based on the mean value of the pipe-roof support effect.

8. A method for evaluating the support effect of pipe-roof support according to claim 7, characterized in that: The calculation method of the pipe-roof support effect value is as follows: wi=xi / (yi+zi)×100% Among them, xi is the vertical deformation of the surrounding rock corresponding to the ith monitoring point, yi is the vertical deformation of the steel pipe corresponding to the ith monitoring point, and zi is the initial support arch settlement corresponding to the ith monitoring point.

9. A method for evaluating the support effect of pipe-roof support according to claim 1, characterized in that: Step 7 also includes the following process: optimizing the structure of the pipe-roof support according to the support effect.

10. A pipe-roof support deformation measuring device for the pipe-roof support support effect evaluation method according to any one of claims 1 to 9, characterized in that: The invention comprises a vault steel pipe and a plurality of fiber grating strain sensors equidistantly arranged along the axial direction thereof. The fiber grating strain sensors are attached to the outer wall of the vault steel pipe. The vault steel pipe is located at the top of the center of the tunnel vault.

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