A tracer migration test carried out around the KD-90 drift in the Kamaishi Mine, Japan was analyzed usingthe computer code “Don-Chan”. Geological structure developing in the rock mass near this drift was carefullystudied for making a 3-D channel network model. It was found that two major fracture sets are developing in therock mass and that the lineations observed on the fracture planes mainly develope in the perpendicular directionto the intersection line between these fracture sets. Those nature of the fracture system implies that these fracturessets were initially formed as the conjugate sets and the stress conditions acting on the rock mass have not somuch changed. A channel network was constructed on the basis of those features of the fracture system. Thetracer migration was fairly well analyzed by the “Don-Chan” code. The applicability of this code was also examined.
We had construct a railway tunnel at the site where the occurance of landslides was feared and in addition there were some private houses. We concerned ourself about bad influences on landslide behaviors and the houses due to shocks caused by blastings used for the construction. The maximum blasting shock occurs during a center cut explosion, which is the first explosion in a borehole among many ones filled with dynamite. First, we designed a criterion to evaluate the risk of landslides on the basis of vibration velocities of the blasting shocks. Next, by the survey of blasting-induced vibrations before and during the construction. we examinedthe permissible volume of center cut dynamite in comparison with the criterion. As a result, the tunnel was successfully excavated with no influence on the houses and landsliding due to blast shock. This report describes the method of investigation and analysis, and the results of observation of landslides during the actual construction.
Generally, clay is not applied to the pressurized injection by a grouting pump, because of clay's weakness and instability as a grouting material. However, it is conversely possible to reduce permeability of extensive rock mass by pouring dilute clayey water into the rock for a long time, because clay has non-hardening characteristic. Authors developed a non-pressurized clay grouting method by using the above-mentioned characteristics and applied this to the construction of underground oil storage caverns. Outline of clay grouting and results are described in this paper.