The Analysis Of Strong Seismic Dynamic Response Of Rocky Slope Collapse

A large number of collapses was triggered by Wenchuan earthquake, one of which is located in the MaLiugou of compound Qingchuan Hui Township has distinct characteristics: the volume of most of rockfall than 5m3, and three of them are 1234.2m3,229.32m3,165.6m3,and the distribution of the accumulation bodies which are overhead throwed and have a certain distance from the collapse origin is scattered. Based on the site investigation from MaLiugou and the data of Wenchuan earthquake,the dynamic response of rocky slope under the action earthquake is analysed and researched by discrete element software 3DEC,and the following major awareness is received:(1)The movements of collapse rockfalls under the action of gravity have obvious difference. Overhead throw is a significant movement characteristic and shows great speed, big block and large distance.(2)The slopes under the action of earthquake often have a terrain amplification effect, and the following always happened at transition positions which are from gentle slope to steep slope,mountaintop where slope is steep,mountain spur and thin ridge, which are the parts where the seismic waves are easily enlarged.(3)There are tension and shear damage in the rock slope in the role of seismic waves.Vertical seismic waves make rock mass generate vertical tensile cracks and the expansion and transfixion of rock mass structural plane and horizontal seismic waves make rock mass generate shearing,then high rock mass on the upper surface of the slope are horizontally or obliquely throwed by the great acceleration due to the action of snake twist crack and ellipsoidal bulging crack,so high rock falling due to earthquake is formed.(4)MaLiugou seismic collapses of the early start falling speed 13.9m/s, initial vertical speed of 9.3m/s, horizontal distance is between the 70~80m; seismic rockfall slope rate falling to 1.5 times that of gravity falling rocks, The average increment of 20m/s; slope movement, the average multiple of 1.56 times the average increment was 11.78m/s; the final movement distance of seismic collcapses of rockfall is 3.26 times than the gravitational collapse of rockfall.(5)Discrete element software 3DEC rockfall is used to simulation the movement of seismic collapse processing, numerical simulation results show that the collapse started from the top and gradually extended to the lower part, which is different from the weight began to collapse from the bottom of the scale-up law. Different methods of seismic wave induce different collapses in a manner which determines. By vertical earthquake waves, the model produce significant tensile cracks;The horizontal seismic waves produce ballistic movement of falling rock; model for monitoring the displacement into a parabolic curve to verify the seismic collapse projectile overhead rockfall characteristics.