Dynamic Stability Study Of Highway Landslide

The highway from Ya'an-Shimian-Lugu is important sections of the State Highway Network. The line through the region where have complex topography and diverse landscape. Faults development along highway, seismic activity frequently. Slope instability often induced after earthquake and damage roads severely, harm to highway and housing construction. It is a pressing problem to ensure slope stability under earthquake. In this paper, take C17 Mofanggou ancient landslide of Ya'an-Lugu highway as an example,based on full study to the engineering geological conditions, use numerical simulation methods to study dynamic response under the earthquake of ancient landslides, then analyze ancient landslide stability and propose the corresponding support measures. Main results as follows:(1 ) Use the finite difference software—Flac3D to simulate dynamic response of the ancient landslide response under earthquake. Layout 9 monitoring points in landslide body .According to numerical simulation of slope dynamic response under earthquake, we can arrive at the following understanding :①Under earthquake, maximum displacement of the ancient landslide is 1.28m, the maximum displacement along the main slip direction is 1m, the obvious deformations mainly concentrate on site that the terrain from gentleness to steepness .Landslide surface has a large amount displacement under earthquake. Vertical acceleration affect Mofanggou ancient landslide deformation greatly , when the vertical acceleration equal to horizontal acceleration, the maximum displacement of landslide is 1.91m, the displacement increased about 50% compared with the vertical acceleration is 0; The maximum displacement is 1.38m along the main sliding direction.Compared with the vertical acceleration is 0,the displacement at junction of sliding body and lower rock mass changed slightly.Therefore, vertical acceleration affect slope surface greatly. ②Maximum unbalanced force of landslide body increase gradually under earthquake, 6 ~ 7s reach its maximum value and then reduce gradually.③Displacement increase with elevation along main sliding direction. At the same elevation ,the displacements of main sliding direction is higher than two sides . At the same location, the displacement decreases with depth increasing.④Seismic acceleration amplification factor increase with the increasing of the elevation and then decreased, maximum magnification factor is 1.95 at elevation 1285m and at the moment the acceleration is 13.7m/s2; Magnification factor is less than 1 at elevation above the 1285m. Acceleration was increased and then decreased with depth, maximum horizontal acceleration amplification factor is 0.67 at the depth of 15m. Landslide thickness is about 15m, so the maximum level acceleration at the area of slip surface.⑤Shear strain increment can be divided into three regions, the elevation was :I area: 1318m ~ 1325m, II area: 1328m ~1339m, III area: 1343m ~ 1348m, the maximum shear strain increment is 0.046,concentrated in east of landslide. Shear strain increment of slope becomes larger when vertical acceleration imposed on the calculation model, as the same as vertical acceleration is 0, the maximum concentration in three regions, maximum value is 0.067, increased about 46% compared with vertical acceleration is 0,Shear strain increment between 0.007 and 0.014 near the sliding surface, unchanged essentially.⑥Landslide surface,landslide perimeter and central part of the landslide area are in a state of tension and shear failure.At elevation 1329m ~1354m, most regions in the shear state at central part of landslides.(2) Considering the dynamic response of the ancient landslide has the horizontal and vertical amplification, design the slope support measures.Through effective inspection,the control measures are effective.