True triaxial shear tests of remolded loess under different matrix suctions

In order to investigate the shear characteristics of remolded loess under suction-controlled true triaxial condition, firstly, soil-water characteristic curve of remolded loess was tested by using the unsaturated soil oedometer, so the relationship between moisture content and matrix suction of remolded loess was obtained. Then, true triaxial shear tests under consolidated drained conditions of remolded unsaturated loess were carried out with matrix suction of 50, 100 and 200 kPa. In the true triaxial shear tests, the net mean stress was kept at 300 kPa and the intermediate principal stress parameters(b-values) were respectively 0, 0.25, 0.50, 0.75 and 1.00. The relationship curves of major principal strain, intermediate principal strain and minor principal strain versus deviatoric stress from true triaxial test results were given. The effects of matrix suction and intermediate principal stress parameter on the stress-strain response of remolded loess were studied. It could be concluded that the shear strength of remolded loess increased with the increase of matrix suction. And it could be summarized that the shear strength of remolded loess decreased with the increase of intermediate principal stress parameter(b-value). The stress-strain curves gradually transformed from strain-hardening type to ideal elastic-plastic type with the increase of intermediate principal stress parameter(b-value). The strength failure line of the remolded loess on π-plane was given. The failure line expanded outward with the increase of matrix suction. Matrix suction might affect the position, size and shape of the failure line. Besides, the test results of different matrix suction were more similar to those predicted by Lade-Duncan criterion. © 2020, Science Press. All right reserved.