Geological Disaster Prevention And Control Measures Of Shield Construction In Kunming Metro In Karst Development Area

The subway shield passes through the karst development area,the complex geological environment conditions make the construction more difficult,and the influence of karst on the subway shield is a fundamental problem to evaluate the stability of surrounding rock and carry out the optimal design.The shape and size of karst and the relative position with the tunnel also have different influence on the subway shield construction.In this paper,the problem of metro shield in karst development area of Kunming Metro Line 6 is discussed.The mechanism and characteristics of karst development are studied.With the help of PLAXIS 2D finite element analysis software,a finite element model is established to study the influence of different shape,size and relative position of karst on metro shield,and the karst treatment measures and metro shield construction parameters are proposed.The results show that the karst development is affected by the formation lithology,geological structure and rainfall conditions;the karst development in the top,side and bottom of the tunnel,to varying degrees,has an impact on the metro shield;different karst shape and size and relative position of karst will change the surrounding rock stress field,displacement field and surface settlement;grouting measures should be adopted in the karst development area At the same time,grouting effect should be ensured.At the same time,select a suitable shield machine,and monitor the shield machine construction process in real time to control the ground settlement and ensure the construction safety.The research results can provide some reference for the design and construction of metro shield in karst areas.