| With the national economic growth and urban development needs,the development of urban rail transit system has been put on the agenda by more and more cities.During the construction of the subway system in the city,the safety problems in the construction process have been widely valued.Among them,the water inrush disaster is one of the major geological disasters common in the tunnel construction process.Once the water inrush disaster occurs,it will affect the progress of the project and cause the loss of life and property.Therefore,it is very important to prevent and control the water inrush disaster in the process of tunnel construction.In this paper,the tunnel between Jialingjiang Road Station and Xiangjiang Road Station of Qingdao Metro Line 13 is taken as the research object.The stability of the tunnel through the fault fracture zone is analyzed by theoretical analysis and numerical simulation.The factors that may cause water inrush disasters are studied,and disaster prevention and control measures are proposed.The specific research contents are as follows :(1)By studying the types of tunnel water inrush disasters,the influence factors of water inrush disasters including geological conditions,meteorological conditions and other conditions are analyzed.The evolution mechanism of tunnel water inrush disasters is analyzed from macro and micro perspectives.It is concluded that the occurrence of water inrush disasters often includes two or more tunnel water inrush evolution modes.(2)Based on the actual engineering background,a model of tunnel crossing fault fracture zone is established to analyze the influence of excavation disturbance on tunnel stability.The excavation nodes are located in different sections of the tunnel construction process,and the results are different.The distribution of plastic zone,pore water pressure,surrounding rock stress and deformation are also different.At the interface of different strata,the plastic zone in the fault fracture zone is the most widely developed and distributed.The pore water pressure rises sharply at the fault fracture zone and the interface between the fault fracture zone and the grade V surrounding rock.The maximum principal stress of the surrounding rock decreases obviously in this section.The settlement of the vault and the arch bottom reaches the maximum value of6.49 mm and 5.86 mm in this section.At the interface of the fault fracture zone and the stratum,the stability caused by the construction excavation is obviously affected.(3)At the center of the fault fracture zone,the effects of different pore water pressures on the stability of the tunnel were studied by setting three working conditions of 0.3 MPa,0.4 MPa and 0.6 MPa.With the increase of pore water pressure,the distribution of plastic zone in the center of fault fracture zone continues to expand,the water pressure gradient around the tunnel continues to increase,and the settlement of vault and arch bottom increases with the increase of pore water pressure.By controlling the pore water pressure variable,it can be seen that when the pore water pressure increases,the tunnel is more prone to surrounding rock damage during construction,resulting in sudden water inrush disaster.(4)According to the development of plastic zone and the change of stress and deformation of surrounding rock in numerical simulation,the grouting reinforcement scheme is designed,and the grouting reinforcement effect is verified by numerical simulation.After grouting reinforcement,the plastic zone in the range of tunnel grouting circle disappears.At the fault fracture zone,the pore water pressure decreases,the properties of surrounding rock become stronger,the permeability decreases,and the settlement of vault and arch bottom decreases,which proves the feasibility of grouting scheme. |
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