A tunnel discrete element influence analysis method based on muon imaging

Abstract

The application provides a tunnel discrete element influence analysis method based on muon imaging, and relates to the technical field of tunnel engineering, and comprises the following steps: obtaining initial parameters of a rock-soil body; adopting a muon imaging method to obtain a disturbance range and disturbance body parameters caused by tunnel excavation completion; performing discrete element analysis based on the initial parameters of the rock-soil body, the disturbance range and the disturbance body parameters to obtain predicted stratum deformation. The above method is based on high-precision muon imaging detection, detectors are arranged in front of a shield to obtain the disturbance body range and parameters after the influence of shield construction, and the final influence degree of tunnel construction on surrounding buildings is obtained according to the volume, density and other characteristics of the disturbance body in combination with the stratum, burial depth, hole diameter and the like of the tunnel, the characteristics of discrete elements and the non-continuous medium characteristics of the rock-soil body are utilized to quantitatively evaluate the safety risk caused by construction; and the building deformation amount predicted according to the discrete element model can guide the adoption of economic and reasonable building protection and reinforcement measures.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology, and in particular to a discrete element method for tunnel influence analysis based on muon imaging. Background Technology

[0002] Tunnel construction inevitably causes disturbance to the surrounding strata due to strata loss during excavation and strata deformation after excavation. However, the magnitude of the strata disturbance and the degree of deformation of surrounding buildings or ground settlement are affected by factors such as burial depth, excavation diameter, and strata characteristics.

[0003] Existing research on ground disturbance during tunnel construction primarily relies on finite element analysis based on ground characteristics and the construction process to determine the extent of ground disturbance and ultimately the magnitude of the impact of tunnel construction on the surrounding environment. The finite element method is suitable for continuous media, and its advantages lie in its ease of obtaining basic data for modeling, calculation, and analysis, its relatively fast computation speed, and its wide applicability.

[0004] However, existing technologies are all pre-analyses based on geological characteristics and specific construction conditions, and cannot take into account the actual construction situation on site. The soil and rock masses around tunnel projects often exhibit discontinuous media and granular movement, so finite element calculations cannot accurately reflect the disturbance of the strata caused by tunnel construction. In particular, there is a lack of effective detection methods for cavities around the tunnel during the construction period, and the finite element method is difficult to realize the process and laws of the development of cavities towards the surface after their appearance.

[0005] Discrete element method (DEM) can analyze the motion state and position information of particles and can analyze the properties of discontinuous rock and soil masses relatively well. However, it is difficult to obtain accurate information on the distribution of strata and cavities in engineering practice. It is necessary to accurately detect the location and size of cavities or disturbances around the tunnel in order to predict the subsequent ground deformation. Summary of the Invention

[0006] The purpose of this invention is to provide a discrete element method (DEM) for tunnel construction impact analysis based on muon imaging. This method addresses the difficulty of existing tunnel construction impact analyses in accurately representing actual construction conditions and surrounding geological formations. It introduces high-precision muon imaging technology to detect geological disturbances in the early stages of tunnel construction and incorporates changes in geological density into the DEM, using these changes to characterize the disturbances. Ultimately, the analysis yields the final impact of tunnel construction on the surrounding geological formations, accurately and quantitatively assessing the safety risks caused by construction to guide safe construction practices on site. The specific technical solution is as follows: A discrete element method for tunneling impact analysis based on muon imaging, the method comprising the following steps: S100, Obtain initial parameters of the soil and rock mass; S200. The disturbance range and disturbance body parameters caused by the completion of tunnel excavation are obtained using the muon imaging method. S300. Based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body, discrete element analysis is performed to obtain the predicted stratum deformation.

[0007] Furthermore, in step S100, based on the survey work before tunnel construction, parameters such as density, porosity, compression modulus, and Poisson's ratio around the tunnel are obtained in sections.

[0008] Furthermore, in step S200, a muon detector is installed as close as possible to the bottom of the cutterhead of the tunnel boring machine or the receiving direction of the detector is adjusted to ensure that the detector can detect the upper half of the tunnel face.

[0009] Furthermore, the muon imaging method can be used to obtain the density distribution of the stratigraphic grid, explore the range of stratigraphic disturbance and stress release after tunnel construction, obtain the geometric characteristics and density properties of the disturbed body, and obtain stratigraphic parameters at different locations.

[0010] Furthermore, the ground disturbance caused by the completion of tunnel excavation is detected by a muon detector. The characteristics of the disturbance include its volume, density, and the location of the corresponding tunnel.

[0011] Further, in step S300, discrete element analysis is performed based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body. Specifically, the density of the strata before and after the disturbance is measured by the muon imaging method, the change in the original strata density is compared, the volume loss of the corresponding grid is calculated, and then the corresponding volume particles are deleted from the discrete element calculation model constructed according to the original strata before discrete element calculation is performed.

[0012] Further, in step S300, discrete element analysis is performed based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body. Specifically, after tunnel construction, the density distribution grid of the stratum is obtained from the muon imaging of the stratum, the porosity of the stratum is calculated, and the micro-parameters of the particles are obtained according to the relationship between the stratum porosity and the micro-parameters of the particles, and then substituted into the discrete element analysis.

[0013] Furthermore, the relationship between formation porosity and particle micro-parameters is obtained as follows: before construction, uniaxial or triaxial tests are conducted on the formation to obtain soil parameters under different porosities, and then the micro-parameters of discrete element particles are calibrated to establish the relationship between formation porosity and particle micro-parameters.

[0014] Furthermore, the calibration of micro-parameters requires multiple sets of experiments, the establishment of a neural network model, and the determination of the relationship between micro-parameters and macro-parameters.

[0015] Furthermore, the microscopic parameters of the particles include normal stiffness, tangential stiffness, and coefficient of friction.

[0016] The present invention provides a discrete element method for tunneling influence analysis based on muon imaging, which has the following beneficial effects: This invention is based on high-precision muon imaging detection. Detectors are deployed in front of the tunnel boring machine (TBM) to obtain the range and parameters of the disturbed body after the TBM construction. Based on the characteristics of the disturbed body, such as volume and density, combined with the tunnel's strata, burial depth, and diameter, the final impact of tunnel construction on surrounding buildings and structures is obtained. Utilizing the characteristic that discrete element method (DEM) matches the discontinuous medium properties of soil and rock, the safety risks caused by construction are quantitatively assessed. Based on the building deformation predicted by the discrete element model, economical and reasonable building protection and reinforcement measures can be taken. Attached Figure Description

[0017] Figure 1 A flowchart illustrating a method for analyzing the discrete element impact of tunneling based on muon imaging, provided in an embodiment of the present invention; Figure 2 A schematic diagram of soil particles before undisturbed strata; Figure 3 A schematic diagram of soil particles after strata have been disturbed; Figure 4 This is a comparison image of the same cross section detected at different times. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0019] Example 1

[0020] This embodiment provides a discrete element method for tunneling influence analysis based on muon imaging. (See reference...) Figure 1 As shown, the method includes the following steps: S100, Obtain initial parameters of the soil and rock mass.

[0021] In one embodiment, based on the survey work before tunnel construction, parameters such as density, porosity, compression modulus, and Poisson's ratio around the tunnel are obtained in sections as basic data for comparative analysis.

[0022] S200. The disturbance range and disturbance body parameters caused by the completion of tunnel excavation are obtained using the muon imaging method.

[0023] In one embodiment, a muon detector is installed as close as possible to the bottom of the cutterhead of the tunnel boring machine, or the receiving direction of the detector is adjusted to ensure that the detector can detect the upper half of the tunnel face.

[0024] In one embodiment, the density distribution of the stratigraphic grid can be obtained using the muon imaging method, which can be used to explore the range of stratigraphic disturbance and stress release after tunnel construction, obtain the geometric characteristics and density properties of the disturbed body, and obtain accurate stratigraphic parameters at different locations for subsequent stratigraphic deformation prediction.

[0025] In one embodiment, ground disturbances caused by tunnel excavation are detected by a muon detector. The disturbance is characterized by its volume, density, and the location of the corresponding tunnel. The criterion for identifying a disturbance is density change; if the density change exceeds a predetermined proportion compared to the density before construction, it is considered a ground disturbance.

[0026] S300. Based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body, discrete element analysis is performed to obtain the predicted stratum deformation.

[0027] In one embodiment, discrete element analysis (DEM) is performed based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed volume. Specifically, the formation density before and after disturbance is measured using the muon imaging method. The change in the original formation density is compared, and the formation volume loss of the corresponding grid is calculated. Then, particles with the corresponding volume are deleted from the DEM calculation model constructed based on the original formation, and DEM calculation is performed again. (See also...) Figure 2 , 3 As shown, if the original mesh A has a density of ρ1 and the number of particles inside it is N1, after being disturbed, the density of mesh A changes to ρ2 after muon imaging detection. Since the properties of individual particles have not changed, the number of particles inside it is N2 = ρ2 / ρ1·N1. In finite element analysis, (N1-N2) particles can be deleted from mesh A to perform discrete element analysis.

[0028] Specifically, formation density can be obtained through pre-construction surveys or through multiple muon imaging. (See also...) Figure 4 As shown, the detection range of the muon imaging is the upper fan-shaped area, which can detect the density of undisturbed rock and soil in front of the shield cutterhead. Through multiple detections under different tunneling conditions, the density of the strata at the same location at different times can be measured.

[0029] In one embodiment, discrete element analysis is performed based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body. Specifically, after tunnel construction, the density distribution grid of the stratum is obtained from the muon imaging of the stratum, the porosity of the stratum is calculated, and the micro-parameters of the particles are obtained based on the relationship between the stratum porosity and the micro-parameters of the particles, which are then substituted into the discrete element analysis.

[0030] Since the properties of the soil and rock particles themselves remain unchanged before and after the disturbance, the loss of the formation after the disturbance is macroscopically manifested as a change in the formation porosity.

[0031] In a preferred embodiment, the relationship between formation porosity and particle micro-parameters is obtained as follows: uniaxial or triaxial tests are conducted on the formation before construction to obtain soil parameters under different porosities. Then, discrete element particle micro-parameter calibration is performed to establish a relationship between formation porosity and particle micro-parameters (normal stiffness kn, tangential stiffness ks, friction coefficient μ). The calibration of micro-parameters requires multiple sets of experiments to establish a neural network model, obtaining the relationship between micro-parameters and macro-parameters, which serves as basic data for subsequent analysis of disturbed formations during construction.

[0032] Specifically, based on the predicted stratum deformation, measures for building protection and reinforcement are guided. When the deformation or internal force of the protected building or structure exceeds the protection standard, the building or structure should be protected and reinforced. The timing of the protection and reinforcement is combined with muon imaging of the disturbed body, and reinforcement is carried out before the stratum reaches the protected building or structure; the method of protection is to perform supplementary grouting reinforcement on the stratum.

[0033] This invention is based on high-precision muon imaging detection. Detectors are deployed in front of the tunnel boring machine (TBM) to obtain the range and parameters of the disturbed body after the TBM construction. Based on the characteristics of the disturbed body, such as volume and density, combined with the tunnel's strata, burial depth, and diameter, the final impact of tunnel construction on surrounding buildings and structures is obtained. Utilizing the characteristic that discrete element method (DEM) matches the discontinuous medium properties of soil and rock, the safety risks caused by construction are quantitatively assessed. Based on the building deformation predicted by the discrete element model, economical and reasonable building protection and reinforcement measures can be taken.

[0034] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the invention. Any changes or modifications made by those skilled in the art based on the embodiments of the present invention and the above disclosure shall fall within the protection scope of the claims.

Claims

1. A discrete element method for tunneling influence analysis based on muon imaging, characterized in that, The method includes the following steps: S100, Obtain initial parameters of the soil and rock mass; S200. The disturbance range and disturbance body parameters caused by the completion of tunnel excavation are obtained using the muon imaging method. S300. Based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body, discrete element analysis is performed to obtain the predicted stratum deformation.

2. The method for discrete element method analysis of tunneling based on muon imaging according to claim 1, characterized in that, In step S100, based on the survey work before tunnel construction, parameters such as density, porosity, compression modulus, and Poisson's ratio around the tunnel are obtained in sections.

3. The method for analyzing the discrete element influence of tunneling based on muon imaging according to claim 1, characterized in that, In step S200, a muon detector is installed as close as possible to the bottom of the cutterhead of the tunnel boring machine or the receiving direction of the detector is adjusted to ensure that the detector can detect the upper half of the tunnel face.

4. The method for analyzing the discrete element influence of tunneling based on muon imaging according to claim 3, characterized in that, The muon imaging method can be used to obtain the density distribution of the stratigraphic grid, explore the range of stratigraphic disturbance and stress release after tunnel construction, obtain the geometric characteristics and density properties of the disturbed body, and obtain stratigraphic parameters at different locations.

5. The method for discrete element method analysis of tunneling based on muon imaging according to claim 4, characterized in that, The ground disturbance caused by the completion of tunnel excavation is detected by a muon detector. The characteristics of the disturbance include its volume, density, and the location of the corresponding tunnel.

6. The method for discrete element method analysis of tunneling based on muon imaging according to claim 1, characterized in that, In step S300, discrete element analysis is performed based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body. Specifically, the density of the strata before and after the disturbance is measured by the muon imaging method, the change in the density of the original strata is compared, the volume loss of the corresponding grid is calculated, and then the particles with the corresponding volume are deleted from the discrete element calculation model constructed according to the original strata, and then discrete element calculation is performed.

7. The method for discrete element method analysis of tunneling based on muon imaging according to claim 1, characterized in that, In step S300, discrete element analysis is performed based on the initial parameters of the soil and rock mass, the disturbance range, and the parameters of the disturbed body. Specifically, after tunnel construction, the density distribution grid of the stratum is obtained from the muon imaging of the stratum, the porosity of the stratum is calculated, and the micro-parameters of the particles are obtained according to the relationship between the stratum porosity and the micro-parameters of the particles, and then substituted into the discrete element analysis.

8. The method for discrete element method analysis of tunneling based on muon imaging according to claim 7, characterized in that, The relationship between formation porosity and particle micro-parameters is obtained as follows: before construction, uniaxial or triaxial tests are conducted on the formation to obtain soil parameters under different porosities. Then, the micro-parameters of discrete element particles are calibrated to establish the relationship between formation porosity and particle micro-parameters.

9. The method for discrete element method analysis of tunneling based on muon imaging according to claim 8, characterized in that, The calibration of micro parameters requires multiple sets of experiments, the establishment of a neural network model, and the determination of the relationship between micro and macro parameters.

10. The method for discrete element method analysis of tunneling based on muon imaging according to claim 8, characterized in that, The microscopic parameters of particles include normal stiffness, tangential stiffness, and coefficient of friction.

Images