GEOLOGICAL SURVEY FOR FRACTURE ZONES IN TUNNEL

Abstract

We have applied three methods of geological survey to grasp fracture zone in tunnel under construction, and compared the results of survey methods each other. The survey methods are 1) High resolution seismic refraction method, 2) Horizontal core boring, 3) TSP (Tunnel Seismic Prediction) system. In High resolution seismic refraction method, more accurate distribution map of elastic wave velocities is obtained as compared with conventional seismic refraction method, and the location of fracture zone can be estimated from the results. In TSP system, estimated location and width of fracture zone are nearly equal to the results of horizontal core boring.