切羽前方弾性波探査の探査精度についての基礎的検討

抄録

TSP survey is one of the geophysical explorations for estimating characteristics of geology ahead of a tunnel face by using the seismic wave. Since this survey has the advantage of relatively wide survey area and of being able to carry out in short time, it has been used under construction site. The result of a comparison of TSP and the geology shows that a concentration area of seismic reflection surfaces corresponds with a fracture zone.
In this paper, we discussed TSP survey accuracy. As a result of the survey and the geology data analysis, an error in predicted position of the fracture zone ahead of tunnel face by TSP is approximately 5m except for some survey data. The main factor of the error with a view of the geology might be a uniformity of rock hardness in the survey area. It shows that it is necessary to pay attention to the assumed Vp for TSP analysis. Therefore, to improve TSP survey reliability, the existing geological data obtaind before the survey should be important.