開発機械・岩盤力学・資源開発技術

[2504] Formulation and Implementation of Effective Stress Coefficient of Rock to FEM

^○FUJII Yoshiaki¹, DASSANAYAKE Anjula², BADRUL A.K.M.B.³, FUKUDA Daisuke¹ (1.Hokkaido University, 2.University of Moratuwa, 3.H-RISE)

司会: 陳友晴(京都大学)

Keywords:Rock、Effective stress coefficient、Formulation、FEM

The authors tried to evaluate four types of effective stress coefficients of rock; one under hydrostatic pressure (Biot's effective stress coefficient), one for peak strength, one for residual strength and one for fractured rock. The types of rock considered were Kimachi sandstone, Bibai sandstone, Inada granite and Shikotsu welded tuff. Biot's effective stress coefficient obtained by conventional hydrostatic compression test method and the coefficient for peak and residual strengths obtained by the modified failure envelope method which was newly developed by the authors decreased with confining pressure. The effective stress coefficient for fractured rock was evaluated under hydrostatic pressure for post-failure specimens and it was slightly smaller than one. An equation which represents the coefficient by stress was derived and implemented into a FEM software. This paper explains the equation and the example of calculation results.