Decision Criteria of Slope Hazards by Multi-step Monitoring using a WSN

Expressways link every city in Japan and serve as a main lifeline in emergencies response. However, slope disasters in recent years of expressways may occur without warning due to unexpected heavy rain. This paper proposes decision criteria for slope hazards using a multi-point and multi-step monitoring system. A sensor module with a mesh networking protocol is developed. A compact battery pack gives the module an operating life of more than three years. The installation position of sensors is decided by the safety factor for the stability of a half-infinite slope. Decision criteria for slope hazards caused by heavy rain are proposed based on laboratory test results. The laboratory results agree well with field experiment results.