This paper interprets the hydromechanical behaviour of a steep, forested, instrumented slope during an artificial rainfall event, which triggered a shallow slope failure 15 h after rainfall initiation. The soil's mechanical response has been simulated by coupled hydro-mechanical finite-element analyses, using a critical state constitutive model that has been extended to unsaturated conditions. Failure occurs within a colluvium shallow soil cover, characterised as a silty sand of low plasticity. The hydraulic and mechanical parameters are calibrated, based on an extended set of experimental results, ranging from water retention curve measurements to triaxial stress path tests under both saturated and unsaturated conditions. Rainfall is simulated as a water flux at the soil surface and suitable boundary conditions account for the hydromechanical interaction between the soil cover and the underlying bedrock. The results are compared with field data of the mechanistic and the hydraulic responses up to failure and are found to provide a very satisfactory prediction. The study identifies water exfiltration from bedrock fissures as the main triggering agent, resulting in increased pore pressures along the soil–bedrock interface, reduced available shear strength and cause extensive plastic straining, leading to the formation and propagation of a failure surface.

中文翻译：

---

人工降雨引发的表面滑坡的水力力学分析：Ruedlingen田间试验

本文解释了人工降雨事件期间陡峭，林木，仪器仪表倾斜的水力力学行为，这在降雨开始后15小时引发了浅层边坡破坏。土壤的机械响应已通过使用耦合至非饱和条件的临界状态本构模型，通过耦合的流体力学有限元分析进行了模拟。崩塌发生在崩塌的浅层土壤覆盖层内，其特征是低可塑性的粉质砂土。在扩展的实验结果的基础上，对水力和机械参数进行了校准，范围从保水曲线测量到饱和和非饱和条件下的三轴应力路径测试。模拟降雨是土壤表面的水通量，合适的边界条件解释了土壤覆盖层与下层基岩之间的水力相互作用。将结果与直至故障的机械和水力响应的现场数据进行比较，发现该结果可提供非常令人满意的预测。这项研究确定了水从基岩裂隙中渗出是主要的触发剂，导致沿土壤-基岩界面的孔隙压力增加，可用抗剪强度降低并引起大量的塑性应变，从而导致破坏面的形成和传播。将结果与直至故障的机械和水力响应的现场数据进行比较，发现该结果可提供非常令人满意的预测。这项研究确定了水从基岩裂隙中渗出是主要的触发剂，导致沿土壤-基岩界面的孔隙压力增加，可用抗剪强度降低并引起大量的塑性应变，从而导致破坏面的形成和传播。将结果与直至故障的机械和水力响应的现场数据进行比较，发现该结果可提供非常令人满意的预测。这项研究确定了水从基岩裂隙中渗出是主要的触发剂，导致沿土壤-基岩界面的孔隙压力增加，可用抗剪强度降低并引起大量的塑性应变，从而导致破坏面的形成和传播。