CN-122017995-A - Method and terminal for determining tunnel surrounding rock pressure arch boundary

CN122017995ACN 122017995 ACN122017995 ACN 122017995ACN-122017995-A

Abstract

The invention relates to the technical field of tunnel and underground engineering construction and safety monitoring, in particular to a method and a terminal for determining the boundary of a pressure arch of a surrounding rock of a tunnel, wherein the method comprises theoretical prediction, field actual measurement and comparison verification; the method comprises the steps of constructing a tunnel surrounding rock pressure arch boundary comprehensive determination system integrating theoretical calculation and field actual measurement, defining a theoretical boundary of a pressure arch by quantifying a radius of a plastic area and a specific proportion position of a tangential stress peak value of an elastic area on a theoretical level, identifying a rock mass property mutation surface by capturing an inflection point of a wave velocity along with depth change in a dispersion curve on an actual measurement level by utilizing propagation characteristics of transient Rayleigh surface waves in a non-uniform medium, and finally, comparing and checking a theoretical prediction result with a field actual measurement result to determine a final pressure arch boundary.

Inventors

ZHU JIANLIN
QIN SU
TANG JIANDONG
Huai Weiqiang
LIU FENG
CHEN PENG
SHI FEI
SHI TUO
LI FEI
FU YONGGANG
Zhang Yongchong

Assignees

中铁西南科学研究院有限公司
中铁一局集团有限公司
中铁二十五局集团第四工程有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. A method for determining the boundary of a pressure arch of a tunnel surrounding rock is characterized by comprising theoretical prediction, field actual measurement and comparison verification; the theoretical prediction step comprises the following steps: Establishing a tunnel surrounding rock mechanical model under a non-hydrostatic pressure condition based on a mole-coulomb elastoplasticity theory; calculating the radius of the plastic region of the surrounding rock to determine the inner boundary of the pressure arch; determining the outer boundary of the pressure arch according to the radial position of the tangential stress maximum value of the surrounding rock elastic region; the on-site actual measurement steps comprise: nondestructive detection is carried out in a tunnel by adopting a transient Rayleigh wave method, vibration signals generated by exciting a seismic source are collected through a detector array, and the signals are processed to obtain a Rayleigh wave dispersion curve; According to the inflection point appearing in the relation of the wave velocity along with the depth change in the dispersion curve, determining the depth position of the inflection point appearing as the inner boundary of the pressure arch, and determining the depth position of the inflection point disappearing as the outer boundary of the pressure arch; The contrast verification step includes: comparing and analyzing the pressure arch boundary obtained in the theoretical prediction step with the pressure arch boundary obtained in the field actual measurement step, and calculating an error between the two; and on the basis that the error is within the allowable range, judging that the pressure arch boundary identified in the field actual measurement step is effective, and determining the pressure arch boundary as the tunnel surrounding rock pressure arch boundary.
2. A method of determining a tunnel surrounding pressure arch boundary according to claim 1, wherein in the theoretical prediction step: the inner boundary of the pressure arch Radius of plastic region of the surrounding rock Radius of tunnel The difference between the two, ; The outer boundary of the pressure arch Maximum tangential stress of the surrounding rock elastic region A kind of electronic device The radial position corresponding to the multiple Radius of tunnel The difference between the two, , wherein, Is a preset value.
3. The method for determining the pressure arch boundary of the surrounding rock of the tunnel according to claim 2, wherein the calculation formula of the radius of the plastic region of the surrounding rock is: , wherein, Is a vertical stress, and is a vertical stress, As a coefficient of the side pressure, In order for the wall-rock to adhere to the forces, In order to achieve the internal friction angle of the surrounding rock, In order to calculate the combined body of the steel frame and the sprayed concrete through the load-structure method and the displacement equivalent principle and provide equivalent supporting resistance for the anchor rod or the anchor cable, Is the analysis angle; Tangential stress maximum value of surrounding rock elastic region The calculation formula of (2) is as follows: ; the radial position The calculation formula of (2) is as follows: , wherein, 、 And As an intermediate parameter, a parameter which is a function of the parameter, 。
4. A method of determining a tunnel surrounding pressure arch boundary according to claim 2, wherein in the theoretical prediction step, the tunnel radius is the same as that of a non-circular tunnel Using equivalent radii calculated by the equi-area method : , wherein, The sectional area is actually excavated for the tunnel.
5. A method of determining a tunnel surrounding pressure arch boundary according to claim 1, wherein in the field measurement step, the layout of the detector array satisfies the following condition: a plurality of low-frequency detectors are linearly arranged along the measuring line and used for receiving vibration signals; The excitation source is located at a predetermined offset from the detector array and ensures that a complete rayleigh wave signal is received.
6. The method of claim 1, wherein in the step of in situ measurement, the method of generating the excitation source is as follows: Paving a rubber plate at the excitation point of the tunnel wall; and knocking the rubber plate in a hammering mode to excite transient earthquake waves.
7. The method for determining the pressure arch boundary of the surrounding rock of the tunnel according to claim 1, wherein in the step of actually measuring on site, the method for obtaining the rayleigh wave dispersion curve specifically comprises the following steps: Processing the acquired vibration signals to generate F-K domain maps of Rayleigh waves; And extracting a base-order Rayleigh surface wave from the F-K domain map, and converting the base-order Rayleigh surface wave to obtain a VR-H domain dispersion curve.
8. The method for determining the boundary of the pressure arch of the surrounding rock of the tunnel according to claim 1, wherein in the step of actually measuring on site, the method for identifying the inner boundary and the outer boundary of the pressure arch specifically comprises the following steps: analyzing the variation trend of the wave speed along with the depth in the dispersion curve; identifying inflection points showing zigzag characteristics in the change trend; and determining the inflection point appearance depth position of the zigzag characteristic as the inner boundary of the pressure arch, and determining the inflection point disappearance depth position as the outer boundary of the pressure arch.
9. The method for determining the pressure arch boundary of the tunnel surrounding rock according to claim 5, wherein the detectors adopt low-frequency moving coil electromagnetic detectors with the frequency of 4Hz, a plurality of the detectors are linearly arranged along a measuring line, the track distance between every two adjacent detectors is 0.5 meter or 1 meter, and the offset distance between the excitation source and the nearest detector is 6 meters or 8 meters.
10. A terminal for determining a tunnel surrounding pressure arch boundary, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements a method for determining a tunnel surrounding pressure arch boundary according to any of claims 1-9 when executing the computer program.

Description

Method and terminal for determining tunnel surrounding rock pressure arch boundary Technical Field The invention relates to the technical field of tunnel and underground engineering construction and safety monitoring, in particular to a method and a terminal for determining the boundary of a pressure arch of surrounding rock of a tunnel, and particularly relates to a method for predicting the range and the form of the pressure arch formed in the surrounding rock after the tunnel is excavated in a nondestructive mode on site. Background When the tunnel engineering passes through the weak broken rock mass, excavation unloading can cause stress redistribution of surrounding rock, so that a plastic region is expanded and a surrounding rock loosening region is formed, and the safety of a construction period and an operation period is seriously threatened. In the process, a pressure arch formed in surrounding rock is used as a key bearing structure for bearing the load of an overlying rock mass and maintaining the stability of a cavity, and the form and the distribution characteristics of the pressure arch directly influence the design optimization of a supporting structure and the long-term safety of a tunnel. Therefore, the range of the pressure arch and the mechanical characteristics thereof are accurately identified and quantitatively analyzed, and the method has important theoretical significance and engineering value for stability control of tunnel engineering. Currently, pressure arches are mainly studied with a focus on theoretical resolution and numerical simulation. Based on elastoplastics, scholars propose various criteria for pressure arch boundaries from the stress redistribution angle, such as taking a tangential stress rising area or a position with equal tangential stress before and after tunnel excavation as a boundary. However, these methods are not unified and rely on theoretical assumptions for many reasons, lacking efficient verification of field measured data. Because the pressure depth of arch is positioned in the rock mass, the boundary of the pressure depth of arch cannot be obtained through direct observation, and the traditional drilling stress test and other methods have the limitations of high cost, large disturbance, limited detection range and the like, the method brings great challenges for the field identification and quantitative analysis of the pressure arch. Disclosure of Invention The invention aims to solve the technical problems, and provides a method and a terminal for determining the boundary of a pressure arch of a surrounding rock of a tunnel, so that the accurate, efficient and nondestructive identification of the boundary of the pressure arch is realized. The invention is realized by the following technical scheme: a method for determining the boundary of a pressure arch of a surrounding rock of a tunnel comprises theoretical prediction, field actual measurement and comparison verification; the theoretical prediction step comprises the following steps: Establishing a tunnel surrounding rock mechanical model under a non-hydrostatic pressure condition based on a mole-coulomb elastoplasticity theory; calculating the radius of the plastic region of the surrounding rock to determine the inner boundary of the pressure arch; determining the outer boundary of the pressure arch according to the radial position of the tangential stress maximum value of the surrounding rock elastic region; the on-site actual measurement steps comprise: nondestructive detection is carried out in a tunnel by adopting a transient Rayleigh wave method, vibration signals generated by exciting a seismic source are collected through a detector array, and the signals are processed to obtain a Rayleigh wave dispersion curve; Identifying the inner boundary and the outer boundary of the pressure arch according to inflection points appearing in the relation of the wave velocity along with the depth change in the dispersion curve; The contrast verification step includes: comparing and analyzing the pressure arch boundary obtained in the theoretical prediction step with the pressure arch boundary obtained in the field actual measurement step, and calculating an error between the two; and on the basis that the error is within the allowable range, judging that the pressure arch boundary identified in the field actual measurement step is effective, and determining the pressure arch boundary as the tunnel surrounding rock pressure arch boundary. Optionally, in the theoretical prediction step: the inner boundary of the pressure arch Radius of plastic region of the surrounding rockRadius of tunnelThe difference between the two,; The outer boundary of the pressure archMaximum tangential stress of the surrounding rock elastic regionA kind of electronic deviceThe radial position corresponding to the multipleRadius of tunnelThe difference between the two,, wherein,Is a preset value. Optionally, the calculation formula o