Estimation of water level collected in an empty tunnel using cross-borehole pulse radar

Abstract

Cross-borehole pulse radar has been employed to explore an empty tunnel using the fast propagation of its excited pulse through the air region inside the tunnel. However, a partially water-filled tunnel is not properly interpreted yet. An effective conversion model to estimate the water level collected in an empty tunnel is developed using the finite-difference time-domain (FDTD) simulation data. As the collected water level inside the tunnel increases, the depth at the fastest time of peak (TOP) deviates exponentially from that at the fasted time of arrival (TOA). This conversion model renders the collected water level inside the tunnel to be estimated with average error of 0.044 m.