Slope Stability And Rockfall Hazard Evaluation Of The Hillslope At The Exit Of Wulidun

With the improvement of the development of C hina a large number of railway traffic projects have been built in the western Sichuan region.The study area of the paper is located in Wolong Town Sichuan Province.The geological conditions at the exit of the Wulidun Tunnel are complex with well-developed joints and fissures and many geological disasters.However these disasters are random and sudden,so there are great safety risks in the tunnel opening construction.The most important factors affecting tunnel construction are slope stability and rockfall.In this paper,the potential failure mode of the slope is studied on the basis of field investigation and relevant data.The stability of the slope is analyzed qualitatively and quantitatively.At the same time,Rocky For3D software is used to simulate and calculate the movement characteristics and influence range of rockfall on the three-dimensional level.It provides a certain basis for geological hazard prevention and tunnel entrance construction.Main works of the paper is followed:（1）In this paper,the characteristics of rock mass structure of the slope of Wulidun Tunnel exit are obtained through field investigation and the potential failure mode of the slope is analyzed.The slope stability is analyzed by the horizontal projection and nature stability of the slope and it is considered that the slope at the exit of Wulidun tunnel is basically stable.However,the toe of the slope,the bottom of the slope and the upper part of the gravel layer on the surface of the slope body is in an unstable state and it has high possibility of slippage and collapse.（2）Slope model is established by ANSYS software and then the model is imported to FLAC^3D to evaluate the stability of natural state,rainstorm state and earthquake state.Under the three working conditions,the slope stability from high to low is the natural>rainstorm>earthquake.The slope is stable in natural state.But it has a tendency to move in the slope gravel layer.In the heavy rain state,the location of displacement is consistent with the natural state.The earthquake has the greatest impact on the slope.The displacement and shear strain increases significantly,the gravel layer on the surface of the slope body is in an unstable state.To sum up,the simulation results are in good agreement with the field investigation.The rock layer on the slope surface is in an unstable state,which has a certain influence on the entrance construction of Wulidun Tunnel.（3）The DEM model of the study area was established based on UAV photography.The number,particle size and distribution of rockfalls are counted.Rocky For3D software was used to simulate the three-dimensional movement path of rockfalls and the movement characteristics of rockfalls are obtained.Based on the indexes of maximum movement speed,kinetic energy and block number of rockfall at the tunnel exit,the classification of rockfall disaster is evaluated as medium danger,which poses a certain threat to the exit of the tunnel.