Numerous studies have demonstrated that the strength and deformation characteristics of coarse-grained materials are significantly influenced by the initial particle size distribution (GSD). However

research on constitutive models for coarse-grained materials that consider this influence is still limited. In this study

we introduced an initial GSD index

ϑ

which reflects the ease of particle breakage and links the initial GSD to the ultimate GSD. We systematically investigated and elucidated the mechanism by which ϑ affects the peak shear strength ()

peak strain ()

and the position of the critical state line (CSL) on the e-p plane. The results regarding the effect of ϑ on qp and  indicate that as ϑ increases

qp decreases

whereas  increases. Based on these findings and the hump-shaped quadratic curve model proposed by Shen Zhujiang

we established a tangent Young’s modulus that considers the effects of initial GSD and confining pressure. The study on the effect of ϑ on the CSL position reveals that a decrease in ϑ leads to a downward shift and a counterclockwise rotation of the CSL. Subsequently

within the framework of critical state soil mechanics (CSSM)

we proposed a state-dependent tangent Poisson’s ratio that considers the effects of initial GSD and confining pressure. For a specific type of coarse-grained material

the model only requires a set of model parameters

and the model’s high accuracy is evidenced by the good agreement between the modeling results and the experimental data.