Investigating the failure mechanism of loess-mudstone landslides with a high water content interface subjected to earthquakes through the shaking table test

Abstract

Loess mudstone landslides are widespread on the Loess Plateau of China and are primarily triggered by earthquakes or heavy rainfall. Field investigations have revealed the presence of a high-water-content layer at the interface, which often serves as a sliding surface for these landslides. However, the dynamic responses and failure mechanisms of these landslides during earthquakes remain unclear. We conducted a comparative shaking table test on Model 2 (the loess-mudstone slope with a high-water-content interface layer) and Model 1 (the loess-mudstone slope without a high-water-content interface layer) to investigate the failure mechanism of the slope under the influence of earthquakes. The test results revealed that water accumulated at the interface, creating a layer with a high water content that resembled a mudflow after shaking. This layer plays a critical role in the dynamic response and failure mechanisms of landslides. Under seismic loading, the pore water pressure within this layer increases to a positive value, reducing the effective stress of the loess. The acceleration amplification factor in the loess layer was approximately 16 % higher in Model 2 than in Model 1, indicating that Model 2 experienced larger inertial forces. Significant seismic subsidence and X-displacement were recorded in Model 2. Additionally, an increase in the electrical resistivity was observed under 0.8 g, suggesting the development and propagation of cracks within the slope. These findings indicate that the high water-content layer loses its strength and starts to slide initially, which then drags the overlying loess layer, resulting in the generation of penetrated tensile cracks, large X-displacement, and subsidence. The slope experiences slippage and tensile cracking failures. This study provides valuable experimental evidence that enhances our understanding of the failure mechanism of this type of landslide.