优先流对土壤水文及滑坡触发的影响

强降雨条件下,岩土中的优先流可通过裂缝、裂隙、生物孔隙等多种大孔隙通道向下快速传播,造成深层土壤孔隙水压力增大和潜在滑动面上抗剪强度的减小。因此,优先流与滑坡触发有密切的关联。结合双重渗透模型与无限边坡稳定分析方法,以四川省都江堰市银洞子沟滑坡风险区的人工降雨滑坡实验为例,根据土壤含水量及孔隙水压力观测数据,模拟强降雨条件下滑坡体内土壤水动力过程,并分析优先流对滑坡触发的影响。结果表明,强降雨条件下的土壤含水量及孔隙水压力快速响应与优先流相关,将双重渗透模型与无限边坡稳定分析方法相耦合,可以量化优先流对边坡稳定性的影响,为滑坡泥石流灾害预警提供更可靠的结果。

The Impact of Preferential Flow onSoil Hydrology and Landslide-triggering

Under high-intensity rainfall, preferential flow in rock and soil can rapidly transport downward through cracks, fissures, biological pores, etc. causing the increase of pore water pressure in deep soil and the decrease of shear strength on potential sliding surface. Therefore, preferential flow is intimately related to landslide triggering. In order to investigate the impact of preferential flow on landslide-triggering, field experiments were conducted in YinDongZi gully, DuJiangYan, Sichuan Province. A parsimonious hydro-mechanical model is developed by coupling a dual-permeability model with an infinite slope stability analysis approach. Based on the measurement of soil water content and pore water pressure, the model simulates the soil moisture dynamics in landslide under the heavy rainfall, which assist the analyzes of the influence of preferential flow on landslide triggering. It concludes that the rapid response of soil water content and pore water pressure under heavy rainfall is closely related to preferential flow, coupling of dual-permeability model and infinite slope stability analysis method enable the direct quantification of the influence of preferential flow on slope stability, which can obtain more reliable landslide-triggering predication.