Research On The Mechanism Of Steep Dip Layered Rock Slopes

A typical slope, Jiguanling slope, which refers to a steep dip layeredrock slope induced by underground mining, was introduced in this paper.According to the geological survey, the mechanism of steep dip layeredrock slope was analyzed, and a FLAC3d numerical model of Jiguanlingslope was built to simulate the deformation and stresses of the slopeunder different condition of underground mining. Then a three-dimensional geometric model was established for limit equilibriumanalysis, from which a method of calculating the safety factor wasobtained. Based on the program DAN3D, the whole process of Jiguanlingrock avalanche was simulated. The following conclusions were obtainedby the above research.1. By the influence of topography, geological formations andunderground mining, the failure mode of steep dip layered rock slope iscomposite. Generally, steep dip layered rocks bend towards the inclineddirection under the gravity. On the condition of underground mining, thefailure mode of rock slope behavior as toppling–slip–rock fall–landslide.2. The main factors of a steep dip layered rock slope includetopography, rock structure, litho logy, karsts, underground mining.3. Numerical simulations show that, a tension fissure graduallycracks at the edge of slope during the initial stage, while the overlyingrocks have flexural deformation. At the start of underground mining,stress of mountain redistribution occurs, leading separation of the layeredrock overlying, and the toe of rocks cracks, causing the decrease of rockstrength. When the seams in the slope are mined, deformation of theoverlying rock increases sharply, meaning the overlying rocks toppling.And the underlying rocks are pushed to slip, and then collapse, thuslandslide occurs. 4. Limit equilibrium analysis shows that in the natural state, theslope is in a steady state. Under the underground mined conditions,overlying layered rock occur toppling layer by layer, and squeeze on theunderlying key strata, which cut from the slip surface and collapse. Thesubsequent toppling rock blocks push the collapsed rocks, acceleratingthe disintegration process of rocks.5. DAN3D simulation shows that frictional model can simulatedebris flow movement of Jiguanling rock avalanche. There are someerrors between simulation results and the distribution of Jiguanling.Simulation results provide speed value for further research of surge effect.The research work presented in this thesis was supported by projectof China Geological Survey with the granted number1212011140011and National Natural Science Foundation of China(NSFC) with the grantednumber41302246.