地下侵蚀对结晶片岩滑坡活动的影响——以日本善德滑坡为例

Effects of Underground Erosion on the Crystalline Schist Landslide:Example of Zentoku Landslide of Japan

为了研究和评价降雨对滑坡活动的影响过程及其作用,利用地表伸缩计、三维地表位移观测计以及地下水流量和地下侵蚀观测计等现场监测仪器,对一典型的日本结晶片岩滑坡善德滑坡内部的地下侵蚀特征以及地下侵蚀与该滑坡活动之间的关系进行了定量的分析和研究。研究结果表明,季节性集中强降雨是导致地下侵蚀发生的主要原因。善德滑坡地下侵蚀主要有连续土砂排泄和集中土砂排泄2种侵蚀类型,而结晶片岩滑坡的异常活动主要与暴雨引起的集中土砂排泄型地下侵蚀作用有关。通过对地下侵蚀和滑坡活动之间关系的分析发现,地下侵蚀对善德滑坡不同滑体活动的影响作用表现出不同的特征。其中,厚度为10～20m的浅层滑体,地下侵蚀的影响作用最为显著,而对于具有深层滑动面的滑体(>20m)其影响作用并不明显。

In order to study the effects of precipitation on the landslide activities,the underground erosion of a typical crystalline schist landslide of Japan-the Zentoku landslide and its relation with the landslide movement are studied by employing extensometers,three-dimensional displacement meters and underground sediment discharge meters on the site.Based on the results of long-term observation,two main types of underground erosion are defined.The observation data indicate that the seasonal concentrated heavy rainfall is the main factor of inducing the significant underground erosion that can cause the abnormal activities of Zentoku landslide.The relation between underground erosion and sliding mass movement shows that the effects of underground erosion present different features on different sliding blocks.Especially,for the sliding block being of shallow sliding plane（10-20 m）,the influence of underground erosion is most outstanding.