Dynamic response and failure mechanism of micropiles in accumulation landslide under earthquake

Micropile is a new type retaining structure extensively used in slope engineering due to its small footprint, low vibration and noise emissions, and simple construction process. This study aims to investigate the dynamic response and failure mechanism of micropiles employed in retaining accumulation landslide under seismic loadings through a combination of shaking table test and numerical simulation. The failure process, observed phenomena and bending moment of micropiles during the test were discussed, and the shear force distribution characteristics of micropiles were meticulously analyzed based on numerical simulation. The findings reveal that under sustained earthquake excitation, the natural frequency of the entire landslide system exhibits a gradual decrease and tends to stabilize during strong earthquakes. The dynamic bending moment of micropiles in accumulation landslide exhibits an "S" shape, with a larger magnitude at the top and a smaller one at the bottom. Furthermore, the shear force distribution demonstrates a distinct "W-shaped" pattern. The damage of micropiles mainly includes the flexural shear combination failure at the load-bearing section (occurs within 1.4 ~ 3.6 times the pile diameter above the sliding surface) and the shear failure near the sliding surface. The study is of great significance to understanding of the strengthening mechanism of micropiles under seismic action and to guiding the design of slope support.