| In the development of hydropower in Southwest my country,due to the characteristics of the topography of the dam site,the relevant layout of the underground tunnel project is often considered as one of the first choices of the designer.At the same time,the "dual carbon" development goal established by the state has promoted the layout of pumped storage power stations across the country.Due to the design characteristics of upper and lower reservoir diversion tunnels and underground powerhouses,this type of power station construction requires the use of underground tunnel engineering to realize the project.Target.However,the construction of underground tunnels is faced with problems such as large construction scale,closed space environment,complex structural settings,fragile geological structure,and harsh working environment,and there are frequent hidden dangers of landslides.Once a sudden landslide accident occurs during the operation,it will cause huge loss of life and property,and bring severe challenges to the construction managers.Therefore,this paper adopts catastrophe theory to carry out research on the coupling evolution of collapse risk in underground tunnel construction.Dynamically identify and screen the collapse risk factors of underground tunnel construction,establish a risk coupling catastrophe model,and analyze the evolution process of collapse risk catastrophe,in order to provide a rational reference for the effective prevention and control of related landslide accidents.The main research contents and conclusions are as follows:(1)Construct a collapse risk index system for underground tunnel construction.The concept of landslide risk in underground tunnel construction is defined,and its characteristics are further analyzed.Based on the theory of accidental release of energy to explore the cause of accidents,the risk of collapse in underground tunnel construction is divided into 6 items,including operators and safety management,and 35 risk factors for collapse are identified and sorted out.Subsequently,the improved variable weight AHP(Analytic Hierarchy Process,AHP)method was used to realize the dynamic screening of risk factors,and the variable weight comprehensive weights of 27 risk indicators after screening were determined,which provided a scientific basis for the ranking of factor importance and the construction of index system.(2)Establish a catastrophic evolution model of landslide risk in underground tunnel construction.Using the time-state analysis method,a landslide risk coupling evolution network is built,and the coupling relationship,evolution process and system state are analyzed from three levels.Based on the catastrophe theory,the risk coupling catastrophe model is established,and the calculation process of the risk coupling degree is introduced.Select human factors and physical factors as control variables,use the cusp catastrophe model to complete the analysis of the evolution process of landslide risk mutation,explore the evolution trajectory and change law of 4 different paths,and divide the system safety state into 5 with the divergence set as the boundary condition area.(3)Carry out engineering case analysis.Taking the Baihetan underground tunnel as the object,it is determined that the coupling degree of construction landslide risk is 0.9689,and there is a medium-strength coupling effect among the factors.The construction system as a whole is located in the lower leaf with a gradual change trend and is in a relatively stable area.According to the cusp catastrophe model,three evolution paths of landslide risk are listed.Then,using the control variable method to explore the sensitivity of single factor and multiple factors,it is found that the sensitivity of hydrogeological risk is greater than the other 5 factors,and the sensitivity of physical risk is much greater than human factor,and any abnormal changes of them will greatly affect the construction of underground tunnels Safety.In order to weaken the coupling strength of factors,optimize the evolution path,improve the system state,and ensure the safety of underground tunnel construction,strict prevention and control measures are required to prevent excessive contact between humans,machines,and energy. |
