Safety Analysis Of Underground Water-sealed Caverns Under Earthquake Action

With China’s economy and society entering the stage of medium and high-speed growth,the country’s demand for oil and gas and other important strategic resources is growing,and the demand for reserve projects is also increasing.In this regard,underground caverns have natural advantages.According to the traditional thinking,the underground structure is confined by deep rock and soil,and its seismic performance is relatively good,and the research on seismic mitigation of underground space structure is far less than that of above ground.In this paper,based on a certain underground cavern project in Qingdao,combined with field survey data,design scheme and so on,through theoretical derivation and numerical simulation,the dynamic response analysis of surrounding rock of the cavern is carried out.Main work: through the deformation of surrounding rock under lateral,vertical and bidirectional ground motions,the stress distribution law and displacement variation law in the change process are studied;the influence of dynamic action on the anchorage system in engineering is studied.The main conclusions are as follows:1.Under the action of ground motion,the deformation of surrounding rock at vault and joint is the biggest,which is the weak area of the whole structure.2.The influence of lateral ground motion on the cavern is the biggest,and it has the tendency of deformation and failure,so it needs to be strengthened;under the vertical ground motion,the influence is small;under the bidirectional ground motion,the maximum principal stress of surrounding rock at the monitoring point is increased by about 15%,which indicates that the bidirectional ground motion has more destructive effect on the cavern structure.3.In the project,the designer provides two bolt support schemes with different spacing,which are scheme a-"1.5mx1.5m" and scheme B-"1.5mx2.0m".The results show that the maximum principal stress of the surrounding rock of the main tunnel after reinforcement is reduced by 4%;under the same conditions,the maximum principal stress of the surrounding rock at the entrance of the connecting passage is 12% less than that of the scheme B,which indicates that the stability of the surrounding rock after reinforcement has been greatly improved;the effect of scheme a is better,and the calculation result is safer.