Abstract: In order to study mechanical characteristics of heterogeneous soils under different conditions, the authors conducted a series of ring shear tests, and compared the differences of shear mechanical characteristics between loess, sand, and heterogeneous soils composed of sand and loess. A comparative analysis was carried out on the differences and their generation mechanisms. The study results showed that under different drainage conditions, the change form of shear stress and shear strength of heterogeneous soil composed of sand and loess were significant different from those of loess or sand during the mutual shearing process. At the same shearing rate, when compared with those of single loess and single sand, the shear strength of sand-loess under different drainage conditions was decreased by 71% and 51%, respectively. During the shearing process, the heterogeneous soil composed of sand and loess presented the shearing mechanical characteristics of cohesive soil. The mechanical characteristic differences between heterogeneous soils and single loess or single sand under different drainage conditions are mainly related to the interaction between sand and loess on the shearing surface and pore water state inside soil body.

Key words: ring shear test, loess, heterogeneous soil, shear speed, pore water