Wireless MEMS-based system for real-time geotechnical instrumentation of active slopes

Landslides, lateral spreading and other similar forms of ground failures due to natural disasters, such as heavy rains, floods and earthquakes, continue to be catastrophic events with extreme economic and societal costs, despite our increased understanding of the mechanisms of failure and large ground deformation, primarily because these events occur without much warning. Realtime monitoring programs are essential to develop warning systems of impending danger from active landslides in any site specific or regional hazard program. Unfortunately the current state-of-the-art in real-time monitoring of active slopes is either based on very expensive monitoring systems or on measurement of ground surface displacements. The work presented in this paper is a major step in the direction of establishing autonomous monitoring technology for soil and soil-structure systems. The MEMS-based in-place inclinometer system, ShapeAccelArray (SAA), is capable of simultaneously measuring 3D soil acceleration and 3D permanent ground deformation up to a depth of one hundred meters, with an accuracy of ±1.5mm per 30m. Each sensor array is connected to a wireless sensor node to enable real-time monitoring as well as remote sensor configuration. This paper presents a brief description of the design of this sensor array and results from full-scale liquefaction and lateral spreading testing, as well as preliminary results from field tests of an active slope in California aimed at validating the measured accelerations and displacements.