Experimental analysis on the mechanical properties of soil−rock mixed fillers with different rock contents on a high embankment

Abstract

The mechanical properties of soil–rock mixed filler are the key factors influencing the high rockfill embankment stability. However, they remain unclear, given the complexity of soil–rock mixed filler structure. To analyze the stability of high rockfill embankment in the construction and operation phases, under the engineering background of a high rockfill embankment with a filling height of 50.6 m in the national highway 316 project within the Qinba mountainous area in China, a series of large-scale triaxial consolidated drained shear tests were performed on two soil–rock mixed fillers with 40% and 70% rock contents. Their stress–strain relation, deformation, and strength characteristics were observed. The applicability of Duncan–Chang model was also determined on the basis of the above tests. Results demonstrate that the stress–strain curve and volumetric strain of the filler with 40% rock content are strain hardening type and shear shrinkage type. The filler with 70% rock content has a weak strain softening, and its volumetric strain is first shear shrinkage and then shear dilation. The filler with 70% rock content has larger peak and critical frictional angles than the filler with 40% rock content. The tangential Poisson’s ratios of the E–B and E–μ models are obtained. The former can approximately reflect the volumetric strain characteristics of the filler with 40% rock content. The latter can approximately reflect those of the filler with 70% rock content. Yet, both models fail to describe the influence of confining pressure on the volumetric strain. The study results provide a reference for the stability analysis of high rockfill embankment engineering and provide parameters for constructing the constitutive model of soil–rock mixed fillers.