Ran LI ¹ Jiangkun He ^2* Han Zheng ² Chenyuan Zhang ² Shuai Zhang ¹

• ¹ Institute of Geomechanics, Chinese Academy of Geologi­cal Sciences (CAGS), Beijing, China
• ² Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, Sichuan Province, China

The absence of a dependable reference basis for early identification of the failure mode of loess landslide results in low accuracy of landslide hazard identification and difficulty in recognizing landslide failure patterns. In this light, this paper analyzes the pre-slip deformation and post-slip damage characteristics of the rotational-sliding Huzhu Landslide and the translational-sliding Zhongzhai Landslide using field investigations, unmanned aerial surveys, and remote sensing interpretation. The physical model tests were conducted to simulate the instability and damage process of rotational and translational loess landslides.Meanwhile, the three-dimensional models and orthophoto graphic images at different stages were obtained using the Contexcapture. This study reveals the difference in initiation modes between the rotational landslide and the translational landslide. The initial stages of rotational sliding landslides are marked by the formation of distinct tensile cracks at the trailing edge of the slope and a minor uplift at the front. As the uplift at the front progresses and numerous extension fissures develop, the slope stability reduces progressively. Upon reaching instability, the sliding velocity of the sliding mass initially accelerates before decelerating, with the majority of the mass remaining on the sliding surface and retaining relatively well structural integrity. At the trailing edge of the landslide, characteristic features such as falling scarps, fractured walls, and sunken grooves can be observed, while the front displays significant bulging phenomena.In contrast, translational sliding landslides are initially characterized by minor tensile cracks at the trailing edge and pronounced deformation at the front. As these tensile cracks penetrate, the slope is prone to sudden instability under external triggering factors. Following the onset of instability, the sliding mass undergoes rapid movement, with only a small part of the mass remaining on the sliding surface. The findings of this study provide a valuable reference for identifying potential failure modes and assessing failure mechanisms in loess landslides.