Study On Influence Of Cavities On Lining Structure Of Shanshutuo Tunnel Under Blasting Vibration

Along with the development of the railway network in China,beside the single track railway tunnel inevitably will build double line tunnel,the situation of the tunnel lining cavity are behind the widespread,both to ensure the quality of the new tunnel and construction schedule,and at the same time to ensure that both the tunnel in the newly built tunnel blasting construction under the condition of structural stability,so the research on the existing tunnel lining structure under the action of blasting hole stability influence is very necessary.In this paper,based on the Shanshutuo tunnel project,the main contents and conclusions are as follows:(1)According to the field monitoring of blasting vibration velocity data analysis to get the Shanshutuo tunnel blasting seismic wave propagation and the experience formula of the reduction rules.The obtained α and K values have a certain guiding effect on the blasting construction in the later stage of the project.(2)Using MIDAS/GTS software,a three-dimensional model was established based on the actual conditions of the Susukto tunnel.By changing the horizontal and vertical lengths of the voids,the influence of the dome void on the displacement,vibration velocity and principal stress of the tunnel lining structure under blasting was studied.Computational results show that the dome void has a significant effect on the vibration velocity and principal stress of the tunnel dome compared with the void-free tunnel.At the same time,the dome velocity and principal stress increase with the increase of void size.(3)Keeping the size of the void unchanged,study the variation of the vibration velocity and the principal stress of the tunnel lining structure under the effect of blasting when the void is located at the vault,left arch waist,and right arch waist..The calculation results show that the void plays the most significant role in increasing the vibration velocity and principal stress at its location.The left arched waist of the Susuktuo Tunnel is located on the frontal explosion side,so the left arched waist cavity is the most unfavorable to the stability of the tunnel lining structure.(4)By changing the critical height of the left arch waist cavity and the surrounding rock level of the model,the variation law of the vibration velocity and the principal stress of the tunnel lining structure under the action of blasting is studied.The results show that the smaller the critical critical height,the more the vibration velocity and the principal stress increase at the left arch waist.The worse the surrounding rock,the more obvious the effect of voids on the increase of vibration velocity and principal stress of the lining particles in the existing tunnel.