Ground Response Curve (GRC)and Excavation Damage Zone Based on an Isotropic Damage Model

摘要

Analysis of stresses and displacements around underground openings is necessary in a wide variety of civil and geotechnical,petroleum and mining engineering problems.In addition,an excavation damaged zone (EDZ) is generally formed around underground openings even in the absence of blasting effects.The dominant cause of irreversible deformations in brittle rocks is damage process.One of the most widely used methods in tunnel design is the convergenceconfinement method (CCM) for its practical application.The elastic-plastic models are usually used in the convergence-confinement method as a constitutive model for rock behavior.The common plastic models used to simulate the rock behavior,does not model the rock realistically and often the important issues such as stiffness degradation and softening are ignored.Therefore,the use of damage constitutive models in the convergence-confinement method is essential in the design process of rock structures.In this paper,the basic concepts of continuum damage mechanics are outlined.Then a solution for a circular tunnel under hydrostatic stress field,with consideration of a damage model for rock mass has been developed.The ground response curve was calculated based on an isotropic damage model,The radius of excavation damage zone was evaluated with the proposed damage model.The convergence-confinement method based on damage model can consider the effects of post-peak rock behavior on the ground response curve and excavation damage zone.The rock brittleness effect on the ground response curve and excavation damage zone can be considered with developed damage model in the convergence-confinement method.