Flowslides and debris flows in granular soils pose a serious threat to human life and man-made structures. Due to rainwater infiltrating into superficial unsaturated soils, rainfall is the most common triggering factor of such landslides, causing a decrease in matric suction and hence in soil shear strength. Early warning systems based on accurate analyses of groundwater response to meteorological factors are widely used to mitigate landslide risk. In such a context, the accuracy of the model adopted to calculate the groundwater field is closely related to the reliability and meaningfulness of hydraulic soil characterization. In this paper, an extensive laboratory investigation regarding the hydraulic behaviour of pyroclastic unsaturated deposits from a vegetated slope monitored on Mount Faito (Campania, Southern Italy) is presented to highlight the importance of hydraulic hysteresis and the presence of roots in shallow soils. Water retention properties and hydraulic conductivity functions were determined, focusing on a drying–wetting cycle. Tests on specimens sampled in the top ten centimetres of the soil profile were also carried out to assess the effects of plant roots on soil hydraulic properties. Inverse analyses were used to estimate the parameters of a hysteretic hydraulic model. Finally, parametric numerical analyses, carried out via a finite element code, were used to highlight the potential effects of the hydraulic characterization on the stability of sloping pyroclastic covers, including all above factors.

颗粒状土壤中的滑坡和泥石流对人类生命和人造结构构成严重威胁。由于雨水渗入表层非饱和土壤，降雨是此类滑坡最常见的触发因素，导致基质吸力降低，从而导致土壤抗剪强度降低。基于准确分析地下水对气象因素的响应的预警系统被广泛用于减轻滑坡风险。在这样的背景下，地下水场计算模型的准确性与水力土壤表征的可靠性和意义密切相关。在本文中，对法伊托山（坎帕尼亚，坎帕尼亚，意大利南部）的介绍是为了强调水力滞后的重要性和浅层土壤中根的存在。确定了保水性和水力传导函数，重点关注干湿循环。还对在土壤剖面顶部 10 厘米处取样的样本进行了测试，以评估植物根系对土壤水力特性的影响。逆分析用于估计滞后水力模型的参数。最后，通过有限元代码进行的参数数值分析用于突出水力特征对倾斜火山碎屑盖稳定性的潜在影响，包括所有上述因素。确定了保水性和水力传导函数，重点关注干湿循环。还对在土壤剖面顶部 10 厘米处取样的样本进行了测试，以评估植物根系对土壤水力特性的影响。逆分析用于估计滞后水力模型的参数。最后，通过有限元代码进行的参数数值分析用于突出水力特征对倾斜火山碎屑盖稳定性的潜在影响，包括所有上述因素。确定了保水性和水力传导函数，重点关注干湿循环。还对在土壤剖面顶部 10 厘米处取样的样本进行了测试，以评估植物根系对土壤水力特性的影响。逆分析用于估计滞后水力模型的参数。最后，通过有限元代码进行的参数数值分析用于突出水力特征对倾斜火山碎屑盖稳定性的潜在影响，包括所有上述因素。逆分析用于估计滞后水力模型的参数。最后，通过有限元代码进行的参数数值分析用于突出水力特征对倾斜火山碎屑盖稳定性的潜在影响，包括所有上述因素。逆分析用于估计滞后水力模型的参数。最后，通过有限元代码进行的参数数值分析用于突出水力特征对倾斜火山碎屑盖稳定性的潜在影响，包括所有上述因素。