Analysis On Dynamic Response Of High Bedding Rock Slope Under Blasting Load

The 13 th Five-Year Plan proposes the improvement of China's modern comprehensive transportation system,the domestic high-speed railway and other infrastructure construction are developing rapidly.China is a mountainous country,there are more and more high-slope projects in the construction of transportation facilities such as railways and highways,the problem of slope dynamics is more and more complicated.In this paper,the construction stability of bedding rock slope under blasting load is studied based on the related engineering of high bedding slope in Jishou station of new Zhangjihuai high-speed railway.The main work is as follows:Through the numerical calculation of static stability,the stability of the high bedding slope of Jishou station is analyzed.The calculation shows that the engineering geological conditions and support forms of the high bedding slope have a significant impact on its stability.The gravelly soil on the surface of the slope has potential instability,which should be removed during excavation;the last step is close to the boundary of railway,with a large suspended area,resulting in a large displacement,so the rigid support form should be adopted.LS-DYNA software is used to establish the model of cutting blasting excavation,the time history curve of blasting load and distribution law of rock slope are calculated and analyzed by fluid solid coupling algorithm.The time history curve of the load obtained is taken as the input load of dynamic calculation.The FLAC software is used to establish the 3D dynamic calculation model of the slope.According to the vibration velocity of the main monitoring points of the slope,the prediction formula of the blasting vibration velocity which considering the elevation effect is established to determine the maximum single explosive quantity in the construction area.Combined with the landform characteristics and slope design height of Jishou station,three groups of slope calculation models with five steps?seven steps and nine steps are established respectively,their height are 38 meters?53.2 meters and 68.4 meters respectively.The dynamic response of slope with different height and platform width under blasting load is calculated and analyzed.The results show that the vibration velocity of rock slope under blasting load has the effect of elevation amplification,which mainly occurs in the range of 40.1 m to 89.9 m from the horizontal distance of explosion source.The vibration velocity and displacement of the foot of the high bedding rock slope are the largest.Increasing the width of the platform can reduce the vibration velocity,displacement of surface and maximum displacement of the slope,and improve the stability of the slope.In order to study the inside dynamic response of the slope,three groups of slope models with the gradient of 1:1.75,1:1.5 and 1:1 are established.The results show that there is a Surface-trend amplification effect on the vibration velocity inside the slope,the steeper the slope is,the deeper the effect range is.the effect range is positively related to the horizontal distance from the explosion source.As for the rock mass on both sides of the structural plane of the high bedding slope,the rock mass below the structural plane is more stable than the rock mass above the structural plane;When the normal stiffness and tangential stiffness of the structural plane increase,the vibration speed of the rock mass on both sides of the structural plane decreases.