Numerical analysis of the initiation and sliding process of the Yigong landslide using a continuous–discontinuous method

In 2000, a high-speed remote landslide occurred in Yigong, Tibet, China, which traveled 10 km within 10 min with a final deposit volume of 300 Mm3, forming a dammed lake and causing huge losses and environmental damage. This study aims to numerically simulate the entire dynamic process of the Yigong landslide under seismic loading, focusing on its initiation and sliding mechanism using a continuous–discontinuous method. This method, which combines the finite element method with the discrete element method, was adopted owing to its overall process capability. Triaxial compression tests on rock specimens extracted from the Yigong region were simulated using this method. The simulation parameters of the landslide were preliminarily determined based on the simulation results that matched the test results in terms of the peak strength and overall trend. A landslide under the action of an earthquake was simulated based on a landslide model established according to the geological data of the Yigong area. The simulation results provided a clear and concrete presentation of five types of cracks in the landslide body, which can explain the initiation mechanism. Moreover, the landslide process was completely presented from initiation to sliding to accumulation, as well as the final material accumulation. It is demonstrated that the continuous–discontinuous method can reproduce the landslide accumulation in terms of the height, material composition, and size with acceptable accuracy compared to field investigations. Furthermore, comparison with previous studies shows good agreement in the velocity of the upper avalanche part and deposition, which further supports the reliability of the method. Based on these results, the initiation and sliding mechanism are discussed in detail. The findings can help in understanding the deformation mechanism of landslides.