IntroductionIn recent years, interest has increased concerning the environmental problem of global warming caused by carbonic acid gas exhaust from burning petroleum fuel. This is because hot dry rock energy and nuclear power plants have been increased again, and because the storage of high level radioactive waste disposal generated by nuclear power plants has been planned in rock caverns several hundred metres under the surface. Studies of these rock structures must not only evaluate the stability of rock structures themselves but also underground seepage flow caused by thermal conduction.Concerning these problems, Ohnishi et al. [1] studied details of the relations between each parameter including physical meanings in the seepage-thermomechanical coupling quasi-static problem and the discretized finite element method using Sandhu 1-2 [2]. They also investigated the discontinuous planes in which cracks and joints existing in rock mass have an important influence for evaluating the local stabilities of the excavated rock surface of slopes and underground caverns. Yoshinaka et al. [3] classified cracks and joints into the four types of small cracks: cracks, joints, shear bands and faults by focusing on the factor of length. Following this study, Sasaki[4] classified them into the two types of non-oriented small cracks and oriented joint sets and presented multiple yield models in which cracks and joints are considered as opening and slip by excavation.The authors developed the deformation-seepage-heat conduction coupled analysis code by using Ohnishi's formulations for the simple handling of nonlinearity. In order to express the influence of joint sets existing in rock mass, the compliance matrix methods presented by Cho[5] are employed. Thus, the anisotropy of deformability and permeability caused by arbitrary oriented joint sets in rock mass can be expressed and presented formulations are examined to confirm the applicability by using underground cavern models containing joint sets.