Sorption of radionuclides on fractured rocks are of importance to understand the migration behavior in crystalline rocks such as granite, in which fractured zones are likely to be major migration paths. In the present study, sorption of cesium on fractured granite was measured by batch and column sorption experiments, and compared with that on fresh granite.
The distribution coefficients for fractured granite, obtained by the batch sorption experiments, were one to two orders in magnitude larger than those for fresh granite. The larger sorption in fractured zones implies that migration of elements in fractured zones could not be as significant as that expected by the higher groundwater velocity. The cesium migration through fresh granite-packed columns could be described by one-dimensional advection-dispersion equation, in which sorption equilibrium was attained.

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In order to investigate the fatigue properties of rocks under cyclic stress, the fatigue test was carried out on four kinds of rocks: OGINO tuff, KIMACHI sandstone, EMOCHI andesite and AKIYOSHI marble. The main results obtained in this study are summarized as follows:
(1) The strain at the maximum stress increases gradually with the increasing cycles. There is no sign of approaching failure and the specimen failes abruptly. This behaviour may be explained by the failure form in tension where failure occurs normally in a direction perpendicular to the applied tensile stress.
(2) The width of stress-strain hysteresis loop of rock under the cyclic tension has a tendency to narrow with the increasing cycles.
(3) The S_r-N curves of OGINO tuff, KIMACHI sandstone and EMOCHI andesite can be expressed by the experimental equation. As to the endurance limit of these rocks, the obtained values are about 69, 75 and 60% of tensile strength respectively.
For AKIYOSHI marble, the S_r-N curve has not been presented clearly, and it is impossible to determine its ex- perimental equation.

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Large-scale collapses are often observed in rock slopes called “dip slope of type II” by author. In this type, the angle of geological separation is larger than it's sliding friction angle, and is smaller than that of the rock slope. When the angle of separation exceeds the angle of the rock slope, the slope is classified into the “dip slope of type III”. In this case, even if the cohesion becomes zero, the rock will never slide as long as the basement of slope is destroyed because the sliding is occurred in the direction that the basement resists against sliding movement.
This angle of dip slope corresponds to the maximum limit of danger for sliding to occur, and is called “critical factor of danger”. Ratio of a factor and the critical factor is defined as “hazard index”, and provides us a criterion to judge the danger of sliding collapse.
When the index is applied to a hill behind of Asagishi railway station and to rock slopes in the vicinity of this station, it was proved that the index provides us with a rough criterion of sliding danger.

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