(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,
Chinese Academy of Sciences,Wuhan,Hubei 430071,China)
Abstract:Unlike metals,rock materials show the Lode angle dependence and other characters in mechanical behavior as a result of frictional effect. Its yield process depends not only on generalized shear stress but also on hydrostatic pressure. In order to construct the unified yield criterion which is widely used and accordant with characters of rock,work and results are as follows. Firstly,considering shear slide and normal compaction,energy related to yield is divided into the sum of shear strain energy on combined mobilized plane together with volumetric strain energy and their formulas are also derived. Secondly,test results show that when rock yields the relationship between the two kinds of strain energy is linear. Based on the result,rock unified yield criterion is established and it can describe basic yield characters such as curves on meridian plane and Lode angle dependence. Thirdly,after the analysis of some widely used rock yield criterions,it is proposed that unified energy yield criterion is a generalized form of these yield criterions. Lastly,the yield strength is calculated and with the following criterions respectively:the unified energy yield criterion,the triple shear energy yield criterion,Mohr-Coulomb yield criterion,Drucker-Prager yield criterion,twin-shear strength theory,Hoek-Brown yield criterion and Murrell yield criterion. The result by the unified energy yield criterion is more accurate and the error is more stable as well especially under high confining pressure and hydrostatic pressure. The intrinsic mechanism of above-mentioned result is analyzed and the qualification of the traditional assumption that shear strain energy retains to be constant when rock yields is confirmed. So the unified energy yield criterion established in this paper breaks through the traditional assumption. The factor such as volumetric strain energy should be considered reasonably in the yield criterion by analyzing the influencing rule of it,which is significant for the accurate quantitative analysis of rock yield characters.
俞茂宏,何丽南,宋凌宇. 双剪应力强度理论及其推广[J]. 中国科学,1985,28(12):1 113-1 120.(YU Maohong,HE Linan,SONG Lingyu. Twin shear stress strength theory and its generalization[J]. Science China,1985,28(12):1 113-1 120.(in Chinese))
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