Prototype Wireless Sensing Nodes for Monitoring Substructure and Subsurface Conditions

With the aging highway infrastructure, growing demands for usage, and constrained funding for repair and rehabilitation, a reliable and cost-effective monitoring of the highway infrastructure has become more important than ever. As highway infrastructure failure or deterioration in many cases is associated with its substructure and subsurface conditions, this study explores the feasibility of integrating a sensing unit–a radio frequency module–and a miniature accelerometer to monitor the subsurface conditions, such as moisture content and possible movements or motions. The prototype of the sensing unit was evaluated through a laboratory flume test that simulates flowslide in a box with a length of 91.4 cm (3 ft), a width of 30.5 cm (1 ft), and height 30.5 cm (1 ft). Two wireless sensing nodes were embedded in the midheight of the soil while other wired accelerometer and piezometers were also installed. Measurements of received signal strength from the radio module on the sensing node revealed the change of water content or water intrusion in the soil. It was also found that the sensing node was able to remotely detect the water content change in comparing to the point measurements from the piezometers. Measurements from the wired accelerometer coincide with pore water pressure measurements and captured the initiation of the flowslide.