Study on strength characteristics of coarse-grained soil considering influence of mixing uniformity

In the existing research, coarse-grained soil is generally regarded as a homogeneous binary mixture, and the influence of of mixing uniformity between coarse and fine particles on its strength characteristics are ignored. Firstly, a quantitative index(Me) was proposed to describe mixing uniformity in coarse-grained soil. Secondly, through static triaxial tests, the inherent relationship between stress-strain curve, elastic modulus, failure strength and shear strength indicators and the Me were explored. Finally, based on the results of static triaxial tests, a modified Duncan-Chang model considering both confining pressure and Me effects was established, and its applicability and rationality were robustly verified. The results show that the stress-strain curve gradually transforms from strain-softening type to strain-hardening type with the increase of confining pressure. As Me decreases, it gradually develops into strain-softening type from strain-hardening type curve. When both confining pressure and Me increase, both elastic modulus and failure strength increase accordingly. The elastic modulus attenuates by 41.3% when Me decreases from 0.25 to 0, and the failure strength attenuates by more than 40% when Me decreases from 1 to 0. As Me gradually decreases, the overall skeleton-dense structure of the sample changes to the local skeleton-void structure and the local suspension-dense structure in different regions, which leads to gradual attenuation of cohesion and internal friction angle with decreasing Me. © 2024 Central South University of Technology. All rights reserved.