Yield characteristics of Q3 loess in true triaxial tests
FANG Jinjin1，SHAO Shengjun1，LI Rong1，FENG Yixin2
(1. Institute of Geotechnical Engineering，Xi?an University of Technology，Xi?an，Shaanxi 710048，China；
2. School of Civil Engineering，Henan Polytechnic University，Jiaozhuo，Henan 454000，China)
Abstract：A series of isotropic consolidation and shear tests under different intermediate principal stress ratio b and constant water content were performed on unsaturated intact loess with various initial suctions using the true triaxial apparatus. The yield curves in the p-s plane and the shear yield curves in the p-q plane of the unsaturated intact loess were studied. A unified expression of suction increase and loading collapse was established in p-s plane. The yielding characteristics of the unsaturated intact loess were discussed under different ratios of b. The yield suction is a constant related to the density and structure of soil. The curve of suction increase and loading collapse was universally described as a parabola. The shear yield curves are arcs in the p-q plane and are part of the yielding cone surfaces in the three-dimensional net principle stress spaces. The yielding surfaces at k0 state in the net principle stress spaces intersect with the circular conical surfaces with the increase of the ratio b，and the unsaturated loess under the condition of k0 yielded with the decrease of the matrix suction and the increase of the intermediate principle stress ratio b.
2016, Vol. 35 
