Simulation analysis of 3D stability of a landslide with a locking segment: A case study of Tizicao landslide in Maoxian County, Southwest China
Abstract. Rock bridges, also known as locking rock masses in landslides, influence the three-dimensional (3D) stability and deformation patterns of landslides. However, it is always difficult to simulate rock bridges with continuous grid models in three-dimensional landslides due to their discontinuous deformation. Tizicao landslide, located in Maoxian County, Southwestern China, is a typical landslide with a super-large rock mass volume of about 1,388.2 × 104 m3 and characterized by a locking segment. To explore a better rock bridge model to simulate 3D stability and deformation behaviors of the Tizicao landslide, three rock bridge models were introduced into the FLAC3D program, including the intact rock mass model (IRMM), the Jennings model (JM), and the contact surface model with high strength parameters (CSM-HSP). The CSM-HSP model was eventually used in the FLAC3D program to obtain the 3D deformation characteristics of the landslide. Also, the two-dimensional (2D) stability of the Tizicao landslide was analyzed using the GeoStudio program. The simulation results indicate that the Tizicao landslide is stable overall under the current conditions, owing to the existence of the locking segment in the southern front, which is consistent with the field deformations and monitoring data. The overall stability and the local deformation of the landslide are found to be influenced by the locking segment when compared to 2D and 3D stability. There is a linear relationship between the locking ratio and the factor of safety (Fos) for the 2D landslide with a locking segment, while an approximate quadratic parabola for the 3D stability. Finally, the laws of the 3D Fos varying with locking ratios and strength parameters of the locking masses and the sliding surface were analyzed. The advantages and disadvantages of the three rock bridge models in simulating the 3D stability of landslides with a locking segment were also discussed.
