Research of long-term mechanical displaced behavior of soft rock

Inoue, Hiroyuki*; Minami, Kosuke*

When it thinks about a stratum disposition system of high-level radioactive waste, it is important to evaluate the long-term mechanical displaced behavior of the near field bedrock which is boundary condition of the engineered barrier that should be evaluated based on the reality. In this research, three following examination was carried out for reliability improvement of long-term dynamic deformation behavior estimate. (1)We evaluated the sedimentary rock of Horonobe where we used Okubo model as while changing hydraulic condition and temperature condition. (2)We carried out the model experiment that inner pressure acted on in order to grasp a movement of near field bedrock. (3)We examined model to evaluate that. As a result, the following things were provided. (1)Sedimentary rock of Horonobe is easy to cause strength degradation for being wet and dry cycles. When the rock is saturated after drying, it is broken along potential cracking. The rock reacts for a change of moisture content sensitively. In addition, a variation of the strength occurs in a little depth remainder. This diffuseness gave the strong influence on failure time. (2)Big plastic deformation may not do elasto-plasticity behavior according to theory for stress modification of rock mass. (3)We think with one of the factor that it produces remainder in prediction and real creep hour that there is as "m = n (conatnt of Okubo model)" simply. Therefore we collect data after peak, and it is necessary to grasp "m /n ". In addition, it is necessary to improve "n" in the model which we can change by environment and stress state on the way.