Abstract
To investigate the utilization of crosshole exploration using high frequency seismic wave, several in-situ measurements were carried out to clarify the rock conditions that civil engineers face in underground construction sites. As the results, the followings were concluded. (1) Measurements using high frequency seismic wave revealed good reappearance and precision. (2) Rock classification, estimation of rock damage by excavation and rock improvement by grouting were evaluated by measuring the primary wave velocity and attenuation. (3) Informations from the repeatedly measured wave velocity and attenuation were used effectively to monitor the construction process.