堆积体内部裂隙对降雨入渗的影响

降雨条件下滑坡体稳定性与裂隙诱发入渗密切相关。为了探究裂隙发育对堆积体降雨入渗的影响,以澜沧江某巨型堆积体坡表发育的裂隙现象为出发点,设计了均质堆积体和主-次裂隙堆积体2种模型。通过室内物理模拟试验及数值分析,并结合土体中的含水率、基质吸力、湿润锋迁移速度及深度的变化趋势可得出以下结论:裂隙型堆积体在降雨1 h和观测23 h的整个时间段内,其湿润锋迁移变化趋势可归纳为入渗加速→峰值→入渗减速→趋向于0;裂隙的存在为雨水入渗提供了有利的通道,雨水可到达土体深部,形成暂态饱和区,随降雨结束又逐渐消散;降雨在裂隙型发育的堆积体中的入渗过程可分为4个阶段,即前期完全入渗、裂隙下方强烈入渗、补偿加速入渗及水平侧渗。研究结果可为后续滑坡复活机理和稳定性评价提供参考。

Effect of Fissures in Accumulation Body on Rainfall Infiltration

Slope stability under rainfall is closely related to fissure-induced infiltration. In an aim of investigating the effect of fissure development on rainfall infiltration in deposits, two models were designed for the fissures developed on the surface of a huge accumulation body along the Lancang River: a model of primary-secondary fissures, and a homogeneous model for reference. Only the shape characteristic of fractures in the actual deposit was considered for the sake of ideal model size. The changes in the moisture content, matric suction, moving speed and depth of wetting front of soil were obtained through laboratory physical model tests and numerical analysis. In the whole time period of one-hour rainfall and 23-hour observation, the migration trend of wetting front can be summarized as infiltration acceleration, peak value, infiltration deceleration, and tending to zero in sequence. Thanks to the favorable channels provided by fissures, rainwater could reach the deep of the soil and form a transient saturation zone which gradually dissipates as the rainfall ends. The infiltration of rainfall in fissured deposits can be divided into four stages: complete infiltration in the early stage, intense infiltration below the fissures, compensated accelerated infiltration, and horizontal infiltration.