基于高密度电法的天然边坡水分运移规律研究

地下水是滑坡变形与失稳的重要影响因子,目前关于天然边坡水分运移过程的研究多借助传感器监测或数值模拟,但尚不能充分满足无扰、快捷的测量要求。针对该类问题,以天然边坡为研究对象,利用高密度电法结合时域反射技术,通过测量边坡土体含水率与电阻率,构建两者的对应关系,据此反演并分析边坡介质地下水的分布特征及迁移规律,验证高密度电法技术在探究天然边坡水分运移规律的有效性。现场试验结果显示:研究边坡土体含水率与电阻率呈明显对数关系;该边坡有效入渗或蒸发深度为2 m,大于该深度范围内,边坡土体含水率随深度增加逐渐减小;中雨强度下埋深为1.3~2.0 m范围内土体含水率激增的主要原因在于后缘裂缝的优势流补给;边坡高含水率(低电阻区)与低含水率(高电阻区)过渡区与后期滑坡滑动面位置高度吻合。

Study on moisture migration in natural slope using high-density electrical resistivity tomography method

Groundwater is an important factor affecting landslide deformation and instability. At present, the research on water transport process of natural slope mostly relies on sensor monitoring or numerical simulation, which can not fully meet the requirements of non-disturbance and fast measurement. In this study, a natural slope is tested using high-density electrical resistivity tomography (ERT) method and time-domain reflectometry (TDR) to obtain the water content in the slope, and the relationship between electrical resistivity of soil and water content is revealed. Furthermore, the distribution and migration characteristics of underground water in slope are inverted and analyzed. Sequentially, the capability of ERT in capturing moisture migration and distribution is verified. Results of in-situ tests show that: water content of soil has obvious logarithmic relation with soil’s resistivity. Moreover, the effective infiltration or evaporation depth of this slope is 2 m, and water content gradually decreases when the depth is greater than 2 m. The main reason for the sharp increase of water content between 1.3m-2m depth under moderate rainfall intensity is the preferential flow through a crack at the back edge of slope. It is also found that the transition zone between highest water content (lowest resistance zone) and lowest water content (highest resistance zone) is highly consistent with the position of sliding zone in subsequent failure of slope.