[en] One of the important issues to be studied by in situ experiments is how to identify and model excavation-disturbed zones (EDZ). Rock properties such as permeability and deformability in the EDZs are possibly changed from the original properties. It is necessary to understand the EDZs for assessing the performance of the geological disposal system for high level waste. The objectives of the studies on excavation disturbance are to identify rock properties and the extension of EDZs, and to understand the mechanism of rock mass response to excavation works. For these objectives, it is necessary to develop the methods of measuring and modeling EDZs. Power Reactor and Nuclear Fuel Development Corporation has carried out the in situ experiments on excavation disturbance in Tono Mine which is the site of soft sedimentary rocks and in Kamaishi Mine which is the site of granitic rocks. The studies in Tono Mine and Kamaishi Mine are reported. The numerical analysis by FEM can simulate the measured variation of rock stress and ground displacement. The size of EDZs was estimated to be 1 to 2 m from excavation surfaces. Fracture, stress redistribution and undersaturation changed rock properties. (K.I.)