A large triaxial investigation of the stress-path-dependent behavior of compacted rockfill

Realistic prediction of the deformation of rockfill structures becomes increasingly important, which requires improved knowledge about the mechanical properties of rockfill materials. However, previous large triaxial tests were usually carried out with a constant cell pressure, and there is uncertainty about the behavior of rockfill along other stress paths. This paper presents the results of a series of large triaxial tests conducted on limestone rockfill specimens along different loading paths. The effect of previous loading history and moisture content has also been investigated. The results show that the stress-strain and volumetric behavior of rockfill are significantly influenced by the loading directions as well as the confining pressures. However, the stress path appears to have only minor influence on the shear strength of rockfill, while the strength envelope exhibits pronounced curvature at low confining pressures and the peak friction angle decreases approximately linearly with the logarithm of the corresponding confining pressure. The previous loading history is revealed to have considerable effect on the stress-strain behavior but small influence on the peak strength of rockfill. In contrast, the moisture content of rockfill has marked influence on both the deformation and the strength characteristics. The implications of the test results are discussed.