2019 Volume 75 Issue 1 Pages 26-39
The authors developed a new survey method, called Tunnel Seismic Probe Drilling (T-SPD), in which drilling vibration data are used (for the evaluation of ground conditions). T-SPD only needs drilling a borehole on a side wall to set receivers as preparation works. Since drilling vibration data is recorded during drilling, T-SPD doesn't prevent a drilling work (at the tunnel face). So far, we have conducted field demonstration tests of the T-SPD using a middle-long boring with a drill capacity of 50 - 150m at three tunneling projects and confirmed its effectiveness. In this paper, we will report the results of two field demonstration tests using an ultra-long controlled boring with a drill capacity of 1,000m. The T-SPD results shows a relatively good agreement with verification data such as P-wave velocity distributions estimated from the ground surface and from the tunnel floor (in other survey methods). In addition, T-SPD can properly evaluate the ground situation where the drilling energy might have been overestimated because of considerable jamming.