Multi-point monitoring of unstable slope with low cost sensor network

Abstract

A low-cost and simple monitoring method for early warning of rainfall-induced landslides has been proposed by the authors. Tilting angles in the surface layer of slope are mainly monitored in this method. A set of equipment has been developed for practical use, which is equipped with a MEMS (Micro Electro Mechanical Systems) tilt sensor and a volumetric water content sensor. In several case studies with this system, including a slope failure test conducted on a natural slope by applying artificial heavy rainfall, it detected distinct behaviors in the tilting angles in the pre-failure stages. Considering these behaviors, the authors has proposed to issue precaution at a tilting rate of 0.01 degrees per hour, and warning at that of 0.1 degree per hour, for conservative decision. The development of this system reduced the cost for slope monitoring reasonably. However, the number of available equipment for each slope is still limited due to financial restriction, and therefore, engineers need to select the position of sensors carefully for effective early warning. This paper introduce authors' recent attempt to develop more low-cost sensor network for slope monitoring. The cost for each sensor node was reduced by around one-third, and consequently, slopes can be monitored at many point, resulting in more meticulous observation of slope behaviors.