| With the continuous advancement of urban construction,the traffic density has gradually increased,and the urban traffic flow has shown an exponential increase.Above-ground road traffic and viaducts can no longer meet saturated urban travel.Therefore,the development of underground transportation has gradually played an important role,and subway travel has gradually eased the city's traffic pressure.Guangzhou City is China's Geological Museum.Karst areas are widely distributed,and the construction of subway projects in composite karst formations has great risks.During the construction of the shield tunnel,the caverns are deformed and collapsed,which further causes the segment tunnel deformation,surface subsidence,and caves.The construction accidents such as mud burst and water gushing have become one of the most feared geological disasters in subway construction.Therefore,this article will take the construction of the Guangzhou Metro in the karst area as the engineering background.The main research contents are as follows:1.Summarize the current status of research at home and abroad,systematically explain the interaction between shield tunnels and karst caves in karst areas and the impact of karst cave collapse on the surrounding environment.Combined with the urgent needs of current urbanization construction,the overall direction of this research is established.2.Analyze the development mechanism and process of karst,and summarize the karst geological distribution in Guangzhou area and the karst summary revealed by subway shield karst drilling,and then establish the collapse theory of karst cave according to the limit equilibrium method,and theoretically analyze the stability of karst cave.3.The finite element analysis software MIDAS GTS and the single factor variable method are used to analyze the influence of the shield tunnel passing through the karst cave at different locations in the compound karst area under a variety of different conditions.,Get the risk impact of different tunnel construction through karst caves.4.The cave collapse caused by the shield tunnel during the excavation or operation process,and then affects the surrounding environment of the tunnel and the surface.Through the analysis of cave collapse under different cave sizes,cave locations and tunnel burial depths,it is concluded that the cave collapse affects the tunnel and surrounding The law of environmental impact,and propose corresponding construction guidance measures.5.Summarize the shield tunneling technology and the selection and advantages and disadvantages of the shield machine in the karst area,analyze the construction methods adopted for the tunnel construction in the composite karst area,and propose the prevention and control measures for the shield construction method in the composite karst area. |
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