岩石及びコンクリートにおける歪みに基づく破壊基準の実験的研究

抄録

A strain-based criterion can possibly serves as a direct and convenient approach for the stability assessment of geo-structures. The purpose of the present study is to experimentally verify the applicability of 2 strain-based failure criteria: 1) critical tensile strain criterion (Fujii, 1994) and 2) critical strain criterion (Sakurai, 1982) to rocks and concrete.Effects of confining pressure, pore pressure, intermediate principal stress, strain rate on the critical tensile strain εTC andcritical strain ε0 have been investigated by triaxial tests and true triaxia tests for 2 kinds of Shirahama sandstone and 4kinds of concretes with different aggregate sizes. The experimental results show that tensile strain εTC and the criticalstrain ε0 are not affected significantly by confining pressure, intermediate principal stress, strain rate and maximum aggregatesize under low confining pressure and intermediate principal stress. However, the critical strain ε₀ become higherthan the maximum strain at failure ε_1f when σ₂>100MPa, which suggests that critical strain criterion (Sakurai, 1982) mayover-estimate load-carrying capacity of structures. In view of this, a new definition of the critical strain has been proposed, which takes the effect of intermediate principal stress into considerations. The proposed definition has a clearerphysical meaning and affected by the intermediate principal stress to a less extent than the original one.