降雨型滑坡浅层滑动对土体含水率变化的响应

降雨是滑坡的重要诱因,以往的研究通常以滑体含水率达到饱和作为滑坡发生的判别指标,实际上多数滑坡发生时仍处于非饱和状态。因此,有必要研究滑坡变形对含水率变化的响应,进一步揭示降雨型滑坡致灾机理。通过野外现场监测、现场模型试验和室内土柱入渗试验等多种手段深入研究土体含水率与降雨型滑坡的相关性。结果表明:①含水率变化速率是降雨型滑坡致灾的关键指标,降雨对滑坡的影响体现在降雨引起滑坡内部含水率增加速率达到峰值进而引起滑坡失稳破坏。②前期降雨过程是含水率变化速率的重要影响因素。久旱后发生高频降雨,易使土体含水率迅速增加。③强降雨是含水率变化速率增大的关键影响因素。在相同初始条件下,降雨强度越大,含水率变化速率越大,且含水率变化速率到达峰值速度越快。

Response of Shallow Sliding of Rainfall-induced Landslide to the Change of Soil Moisture Content

Rainfall is a crucial causative factor of landslide.In previous studies,water saturation is usually taken as the criterion for landslide occurrence;as a matter of fact,however,most landslides are still in an unsaturated state when they occur.The response of landslide deformation to changes in water content is investigated to further reveal the mechanism of rainfall-induced landslides.The correlation between soil moisture content and rainfall-induced landslides is examined through various methods inclusive of field monitoring,field model tests and indoor soil column infiltration tests.The results manifest that:1) The change rate of water content is a key indicator of rainfall-induced landslides.Due to rainfall impact,the rate of water content increment peaks and then results in the instability and damage of landslide.2) Rainfall process in the early stage is an important factor which affects the rate of water content change.The water content of soil is prone to surge under high-frequency rainfall after a prolonged drought.3) Heavy rainfall is the key influencing factor for the increase in the change rate of water content.Under the same initial conditions,the greater the rainfall intensity,the greater the change rate of water content,and the faster the change rate of water content reaches peak.