CN-122019925-A - Method for determining safe distance between broken surrounding rock and water-rich high-pressure karst cave

Abstract

The invention discloses a method for determining a safe distance between broken surrounding rock and a water-rich high-pressure karst cave, and belongs to the field of underground structural engineering. The method aims to solve the problems that in the prior art, the error is large, numerical simulation is complex and time-consuming, and the safety distance calculation is inaccurate due to the fact that the multi-factor coupling effects such as blasting disturbance and water pressure are not fully considered. The technical scheme is characterized in that the safe distance is divided into three parts, namely the thickness of a damaged zone at the excavation side of a tunnel, the thickness of a protective layer and the thickness of an affected zone at the karst cave side, the thicknesses of the three parts are respectively determined through analysis and calculation methods of multi-field coupling such as fusion blasting stress wave, explosive gas, karst cave water pressure permeation, stress wave reflection and the like, and finally the three parts are overlapped to obtain the accurate safe distance. The invention improves the calculation precision and efficiency of the safe distance, and is suitable for risk control of projects such as tunnels, mines, underground caverns and the like.

Inventors

• WANG XIAOHUI
• HU KAIXU
• LI SHAOBO
• Jiao Hongkun
• Lian Yunbiao
• ZHANG GUOHUA
• WANG YONGYU
• XU TAO
• JIANG LIQING
• WANG LIEN
• WANG BIAO
• LI KE
• ZHANG NUOYA
• PU KE
• BAO RUI
• Zou Junchuan

Assignees

• 中铁七局集团有限公司
• 中铁七局集团武汉工程有限公司
• 中国地质大学（武汉）

Dates

Publication Date

20260512

Application Date

20260212

Claims (10)

1. 1. A method for determining a safe distance between a broken surrounding rock and a water-rich high pressure karst cave, comprising the steps of: Acquiring physical and mechanical parameters of surrounding rock and geometric parameters of karst cave in an engineering area; decomposing the safe distance into the thickness of a damaged zone at the tunnel excavation side, the thickness of an intermediate protection layer and the thickness of an affected zone at the karst cave side; Calculating the thickness of the damaged zone on the excavation side of the tunnel according to the physical and mechanical parameters of the surrounding rock, the geometric parameters of the karst cave and the blasting parameters, wherein the calculation process couples the action effect of blasting stress waves and explosive gas; calculating the thickness of the karst cave side influence zone according to the physical and mechanical parameters of the surrounding rock, the geometric parameters of the karst cave and the water pressure of the karst cave, wherein the calculation process couples the action effect of the osmotic water pressure and the reflection of the stress wave; determining the thickness of the intermediate protection layer; And adding the calculated thickness of the damaged zone on the tunnel excavation side, the thickness of the middle protection layer and the thickness of the affected zone on the karst cave side to determine the final safe distance.
2. 2. The method of claim 1, wherein the step of determining the position of the substrate comprises, The process of decomposing the safe distance comprises the step of linearly superposing the safe distance as the thickness of a surrounding rock damaged zone caused by tunnel excavation, the thickness of an affected zone caused by the existence of a karst cave and the thickness of a protective layer between the two.
3. 3. The method of claim 1, wherein the step of determining the position of the substrate comprises, Calculating the thickness of the damaged zone on the excavation side of the tunnel comprises the steps of respectively determining a crushing zone range formed by blasting shock waves, a damage zone range caused by stress wave disturbance and a crack expansion zone range generated by the action of explosive gas, superposing the damage zone range and the crack expansion zone range, and subtracting the superposed crushing zone range to obtain the final thickness.
4. 4. The method of claim 3, wherein the step of, Determining the range of the damage area caused by stress wave disturbance comprises the steps of establishing surrounding rock yield conditions based on Hooke-Brownian strength criteria, substituting stress wave attenuation rules generated by blasting into the yield conditions for solving so as to obtain the critical radius of the damage area.
5. 5. The method of claim 3, wherein the step of, Determining the range of the crack expansion zone generated by the action of the explosive gas comprises the steps of establishing a composite stress intensity factor model containing the original rock stress and the explosive gas pressure based on fracture mechanics theory, determining the expansion length of the crack when the crack is stopped according to the fracture toughness of the rock, and further obtaining the range of the zone.
6. 6. The method of claim 1, wherein the step of determining the position of the substrate comprises, Calculating the karst cave side influence zone thickness comprises the steps of respectively determining a permeability damage area range caused by the permeability of karst cave water pressure and a fracture area range generated by reflection of blasting stress waves on karst cave walls, overlapping the permeability damage area range and the fracture area range, and deducting the radius of the karst cave to obtain the final thickness.
7. 7. The method of claim 6, wherein the step of providing the first layer comprises, Determining the range of the permeability failure zone comprises constructing a surrounding rock microcell balance equation considering the action of permeability, combining a mole-coulomb strength criterion, and solving the position of an elastoplastic state transition boundary to obtain the range of the zone.
8. 8. The method of claim 1, wherein the step of determining the position of the substrate comprises, The karst cave water pressure is the sum of undisturbed hydrostatic pressure, additional hydrostatic pressure caused by seasonal rainfall and dynamic water pressure induced by tunnel construction disturbance.
9. 9. A computer terminal device, comprising: one or more processors; A memory coupled to the processor for storing one or more programs; when executed by the one or more processors, causes the one or more processors to implement the steps of the method of any of claims 1-8.
10. 10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method according to any of claims 1-8.

Description

Method for determining safe distance between broken surrounding rock and water-rich high-pressure karst cave Technical Field The invention belongs to the technical field of underground structural engineering, and particularly relates to a method for determining a safe distance between broken surrounding rock and a water-rich high-pressure karst cave. Background In the field of underground structural engineering, in particular tunnel excavation, mining and underground cavity construction, geological conditions in which broken surrounding rock and a water-rich high-pressure karst cave coexist are often encountered. Construction is carried out in the poor geological areas, and disasters such as instability of surrounding rock, cave-in, mud bursting and water gushing are extremely easy to induce, so that engineering safety and constructor life safety are seriously threatened. Therefore, the accurate calculation of the reasonable safe thickness between the tunnel wall or the excavation contour line and the hidden karst cave is a key technical link for realizing effective control of engineering risks. Currently, the method for determining the safe distance in engineering practice mainly depends on empirical formula estimation and numerical simulation calculation. The empirical formula method is generally based on simplifying assumptions and historical statistical data, and the heterogeneity of broken surrounding rock, the discreteness of mechanical parameters and the dynamic change characteristic of karst cave water pressure are not fully considered, so that the calculation result tends to have larger errors, and the construction decision of a high-risk zone is difficult to accurately guide. The numerical simulation method, for example, a three-dimensional fluid-solid coupling model is established by adopting FLAC3D and other software, and although the distribution of a surrounding rock stress field and a seepage field after tunnel excavation can be simulated and the safe distance is searched through iterative calculation, the method has obvious limitations. Firstly, the modeling process is complex, a large amount of rock and soil parameters which are difficult to accurately acquire are required to be input, and the preparation work is time-consuming and labor-consuming. Secondly, the numerical calculation is long in time consumption, and urgent requirements of a construction site on quick evaluation and real-time decision cannot be met. More importantly, the conventional numerical method focuses on two-field coupling analysis of a seepage field and a stress field, and key factors such as blasting disturbance load, damage degradation of a rock mass due to blasting and geological structures, dynamic fluctuation of karst cave water pressure caused by seasonal change and construction disturbance and the like in the tunnel excavation process cannot be systematically brought into a unified analysis frame. In addition, the selection of the safety coefficient in the prior art depends on subjective experience judgment of engineers to a great extent, and lacks an objective and quantitative determination basis directly related to the surrounding rock breaking degree, the specific scale of the karst cave and the water pressure, so that scientific balance between the safety reserve and the economic cost of engineering is difficult to achieve. In view of the above problems, the industry has sought a safe distance determination method that can not only ensure the calculation accuracy, but also improve the calculation efficiency, and can comprehensively reflect the multi-factor coupling effects of blasting, water pressure, surrounding rock damage and the like. However, due to the complexity of the interactions of the broken surrounding rock and the karst cave system, creating a set of analytical or semi-analytical computational models that can accurately describe each physical process and facilitate engineering applications faces many difficulties. This constitutes a technical bottleneck in the art that is in need of solution. Disclosure of Invention In order to solve the technical problems, the invention provides a method for determining the safe distance between broken surrounding rock and a water-rich high-pressure karst cave, so as to solve the problems in the prior art. In a first aspect, to achieve the above object, the present invention provides a method for determining a safe distance between a broken surrounding rock and a water-rich high pressure karst cave, comprising the steps of: Acquiring physical and mechanical parameters of surrounding rock and geometric parameters of karst cave in an engineering area; decomposing the safe distance into the thickness of a damaged zone at the tunnel excavation side, the thickness of an intermediate protection layer and the thickness of an affected zone at the karst cave side; calculating the thickness of the damaged zone on the excavation side of the tunnel according to the physi