Analysis of the Ratio of Crack Opening Dependency (RCOD) by Crack Homogenization Model.

When the stresses are relieved by underground excavations, the rook mass tends to deforms perpendicular to the free surfaces and simultaneously macroscopical open cracks which is parallel to the surface are observed. In this case, the deformability of rock mass is largely dependent on the existence of open cracks, and the amount of crack opening is an important factor to the rock mass evaluation.In this study, the Ratio of Crack Opening Dependency (RCOD) is proposed as a new index to evaluate the property of cracked structure which contains many open cracks within. The RCOD is an index which is defined as the ratio of total amount of crack opening and the total deformation of cracked structure. The mechanical property of RCOD is also numerically analyzed by applying SC-DDM (stress compensation-displacement discontinuity method) to 2-dimensional crack homogenization model. Here, the alternative model of a single crack set is assumed and the relation between RCOD and effective Young's modulus of the model is analyzed. The relation between RCOD and stress intensity factor is also discussed and the rationality of the analysis is confirmed. It is shown that RCOD is an useful index which directly indicate the effective Young's modulus and the stress intensity factor of cracked structure without any values such as stresses or crack size. The possibility of application of RCOD to the field measurements is also discussed.