粘性土の平面ひずみ非排水伸張試験における分岐解析とその圧縮試験との比較

抄録

This paper investigates inhomogeneous deformation behavior of clay under the plane strain undrained extension loadings based on bifurcation theory. Constitutive equations of clay are applied for a coaxial and a non-coaxial Cam-clay model. Development locations and forms of slip surfaces are estimated based on distribution of maximum shear strain at the occurrence of bifurcation. Bifurcation stress ratios with lower symmetric modes are smaller under extension loadings than any other mode. The smallest bifurcation stress ratio under extension loadings is larger than the smallest ratio under compression loadings. However, bifurcation stress ratio in extension tests is smaller than in compression tests in the case of lower symmetric modes that the influence of the allowable eccentric load is small. Slip surfaces observed under compression loadings develop from the center of the inside to the side in the end face at top and bottom. In extension tests, however, slip surfaces develop from the exterior at the point of greatest narrowing to the inside.