Effect of Interlayer Dip Angle on the Mechanical Response of Xigeda Sandstone–Mudstone Model Slopes Under Rainfall Conditions

作者：Qianping Du, Lei Deng, Zitong Wang, Chen Wang · 发表于：Water · 年份：2026 · DOI：10.3390/w18060718 · 研究领域：Landslides and related hazards、Geotechnical Engineering and Analysis、Soil and Unsaturated Flow

The strength of Xigeda strata decreases significantly upon contact with water, and the shear strength between sandstone and mudstone layers is lower than that within the individual layers. Therefore, the interlayer dip angle plays an important role in determining the failure mode of rainfall-induced landslides. To investigate the effect of interlayer dip angle on the mechanical response of Xigeda sandstone–mudstone slopes under rainfall conditions, a total of five model slope tests were conducted. Different ratios of model materials were selected for the sandstone and mudstone, and artificial rainfall with intensities representative of the Panxi region was simulated using a calibrated rainfall device. A combination of photography and instrument measurements was employed to study the seepage field, deformation field, and slope failure characteristics at five interlayer dip angles. It is shown that when the interlayer dip angle is smaller than the slope angle, an increase in the interlayer dip angle accelerates the movement of the wetting front along the weak interlayer plane. At the same time, this increase shortens the time to the occurrence of abrupt displacement and increases the corresponding displacement magnitude, which makes slope failure prediction more challenging. The shoulders of all slopes experienced displacement earliest and exhibited the largest displacement amplitude. The slope failure mode transitioned from shallow surface sliding to interlayer sliding. When t...