Evaluation of dynamic stability and analysis of reinforcement measures of a landslide under seismic action: a case study on the Yanyangcun landslide

Earthquakes are a major landslide trigger, and evaluation of the dynamic stability of landslides under seismic action is very important. The Yanyangcun landslide, which is located at route marker K92 of the Xianggelila to Lijiang expressway in Yunnan Province, China, was chosen as a case study. Using the three-dimensional finite difference method and the unbalanced thrust method, three mechanical indices of the sliding zone, including the volume ratio of the elastic or plastic elements, the permanent displacement, and the residual thrusts of the slices, were calculated to evaluate the progressive failure and dynamic stability of the landslide when exposed to different intensities of seismicity. The safety factor of the landslide with reinforcement measures was also assessed. The critical peak seismic acceleration was about 2.29 m/s², between earthquake intensity of VIII degree and IX degree. The landslide experienced progressive failure by means of shear at the leading edge, tension at the trailing edge, and immobilization of the middle part. The middle part of the sliding zone underwent a “locking effect,” which could effectively resist the immobilization of the plastic zones of the leading edge and the trailing edge. With reinforcement measures, the dynamic stability of the landslide under VIII degree and IX degree events satisfied the allowable safety factor of the local specifications. The results provide guidance for disaster prevention and aseismic design for the Yanyangcun landslide, and can also be used as reference information for dynamic stability evaluation of other landslides threatened by earthquakes.