Dynamic response and deformation failure mechanism of fault-controlled slope in Qinghai-Xizang Plateau under strong earthquake action

<p indent="0mm">In the eastern margin of the Qinghai-Xizang Plateau, the rugged mountainous terrain and complex geological conditions, coupled with active tectonic movements and well-developed fault zones, lead to frequent fault-controlled high-elevation landslides. These pose severe challenges to major infrastructure planning and construction, as well as threats to human life and property. However, the current understanding of the dynamic response and deformation-failure mechanisms of fault-controlled landslides remains largely confined to geological surveys and numerical simulations. Large-scale physical model tests grounded in real-case scenarios are still lacking. This study takes the Mogangling landslide as a prototype, employing a similarity ratio of 1:50 in a series of shaking table tests. The results reveal a pronounced nonlinear elevation amplification effect in both slope surface and internal slope acceleration responses. Along the horizontal direction of the fault zone, the fault exerts a significant amplifying influence on horizontal acceleration, with the peak horizontal acceleration (PHA) amplification factor reaching its maximum at the fault location, whereas its impact on vertical acceleration is negligible. When the input seismic intensity exceeds 0.3<italic>g</italic>, dynamic earth pressure peaks on both the hanging wall and footwall of the fault zone increase rapidly, with the hanging wall pressures consistently higher than those on the footwall. At the same elevation, displacement responses on the left slope (which contains the fault zone) are significantly greater than those on the right slope (which lacks a fault zone). The horizontal displacement response also exhibits a clear elevation amplification effect. As loading conditions progress, the fundamental frequencies of both slopes decrease, and the slope containing the fault zone consistently shows lower fundamental frequencies and a faster reduction rate. High-speed camera analyses of deformation-failure mechanisms in the fault-controlled slope under seismic loading indicate that slope failure primarily occurs in the hanging wall of the fault zone, dominated by tensile failure. A superficial, slope-surface-penetrating crack develops at the rear of the sliding mass in the upper portion. The hanging wall slope undergoes substantial downslope collapse, while the footwall remains relatively undeformed, clearly demonstrating the differential deformation on either side of the fault. With incremental loading, the fault-controlled slope gradually forms a continuous potential slip surface extending from the upper slope surface down to the front of the fault zone. Using a real-case scenario from the Sichuan–Xizang region, this experiment elucidates the dynamic slope response and deformation-failure mechanisms of fault-controlled high-elevation landslides under seismic action. The findings offer theoretical support for railway planning, construction, and disaster prevention and mitigation in adjacent areas.