Influence of stone content, relative density, and gradation on shear dilatancy characteristics of rock–soil mixtures

Abstract This study investigates the shear dilatancy behavior of rock-soil mixtures (RSM), sourced from the Three Gorges Reservoir area, using a triaxial testing apparatus, with a focus on the effects of stone content, relative density, and gradation. These factors are of critical importance in marine geotechnical engineering, particularly in the construction of seawalls, underwater foundations, and other coastal infrastructures. The results of this study provide valuable insights into improving the stability and longevity of marine structures under harsh environmental conditions. A triaxial testing apparatus was employed to perform consolidation drainage shear tests under various confining pressures. The results indicate that stone content, relative density, and characteristic particle size significantly affect the Duncan-Zhang model parameters and the deformation behavior of RSM. Improved shear dilatancy equations for RSM were developed, incorporating phase change stress ratios (Md) specific to different influencing factors. The proposed equations provide accurate predictions of shear contraction and dilatancy, enhancing the understanding and prediction of RSM performance in engineering applications, particularly in the context of marine geotechnical engineering. This study offers a novel approach and a valuable tool for examining soil mechanics, paving the way for further theoretical research and practical applications in both terrestrial and marine environments. Graphical Abstract Improved shear dilatancy equations, the study offers accurate predictions of shear contraction and dilatancy behavior, contributing valuable insights into the design and performance assessment of engineering structures involving RSM. HIGHLIGHTS Investigation of shear dilatancy characteristics of rock-soil mixtures (RSM). Influence of stone content, relative density, and gradation on RSM deformation and shear dilatancy. Development of improved shear dilatancy equations incorporating phase change stress ratios (Md). Accurate predictions of shear contraction and dilatancy behavior in RSM.