ABSTRACT

Recent developments in sensing and monitoring technology allow the application of various sensors and sensor networks for tunnel maintenance. Most maintenance monitoring techniques focus on measuring physical parameters of and within the tunnel structure it-self, with less emphasis placed on the ground conditions surrounding the tunnel structure. Soft soil, weak soil or grouted soil zones are particularly susceptible to long-term changes in ground condition and thus, extensive monitoring is essential to ensure long term tunnel stability and accurate numerical analysis. This study proposes a ground monitoring sensor system for tunnel maintenance using geophysical techniques. The proposed system uses seismic wave velocity and electrical resistivity techniques to estimate the changes in the geomechanical properties of the ground. A low cost prototype sensor was created using open source hardware and software and preliminary tests were conducted on an open area test site. The results show that the system can adequately perform seismic and electrical resistivity tests for tunnel maintenance purposes.