Expansive soils are widespread in the world and coincide with areas of high human activity. The main cause of deep instability of expansive soil slopes is due to their softening caused by excavation and seepage. By developing a comprehensive numerical model based on the theory of unsaturated soil, this study examines the characteristics of stress and displacement distribution of expansive soil slopes through hydraulic‐mechanical coupled numerical simulation. This study analyzes the evolution patterns of slopes with excavation unloading and seepage of water storage to reveal the mechanisms of deep‐seated instability of expansive soil slopes. The findings demonstrate that: The instability of expansive soil slopes begins at the foot of the slope and propagates along the interlayer, affecting the entire slope. Excavation leads to the softening of the expansive soil interlayer and the transfer of shear stress. During water storage, the weakening of the soil strength results in slope instability along the weak interlayer slip. Softening of the expansive soil interlayer facilitates the redistribution of shear forces in the slope and alters the distribution law of the plastic zone in the deep layer. Overly slowing down the slope leads to significant excavation unloading, which is detrimental to the slope's stability.

中文翻译：

---

基于应变软化的软弱夹层膨胀土边坡失稳机理研究


膨胀土壤在世界各地都很普遍，并且与人类活动频繁的地区相吻合。膨胀土边坡深层失稳的主要原因是开挖渗流引起的软化。本研究通过建立基于非饱和土理论的综合数值模型，通过水力耦合数值模拟研究膨胀土边坡的应力和位移分布特征。本研究通过分析边坡开挖卸荷和蓄水渗流的演化规律，揭示膨胀土边坡深层失稳机制。研究结果表明：膨胀土边坡的失稳从坡脚开始，沿夹层传播，影响整个边坡。开挖导致膨胀土夹层软化，剪应力传递。蓄水期间，土体强度减弱，导致边坡沿弱层间滑移失稳。膨胀土夹层的软化有利于边坡剪力的重新分布，改变了深层塑性区的分布规律。过度减慢边坡速度会导致开挖卸荷显着，不利于边坡的稳定性。