During the excavation process of foundation pit and tunnel, or soil under vehicle load, wave load and other loads, the amplitude of principal stress acting on the soil changes constantly, meanwhile principal stress axes rotate constantly. It can be seen that rotation of principal stress axes (RPSA) has a large influence on the mechanical properties of soil. 

However, there is no a constitutive model for frozen soil considering the influence of RPSA at present, a constitutive model for frozen saline soil considering the influence of RPSA is proposed in this study. 

Recently, a research group led by Prof. LAI Yuanming from the Northwest Institute of Eco-Environment and Resources of Chinese Academy of Sciences proposed a constitutive model for frozen saline soil and study the mechanical and deformation properties of frozen saline soil under RPSA.  

They proposed a plastic modulus formula considering the effects of hydrostatic pressure, generalized shear stress, and anisotropy and presented a dilatancy equation which can reflect the effect of intermediate principal stress coefficient. 

It is found that the proposed model not only can reflect the effect of the increase of principal stress amplitude on the mechanical and deformation behaviors of frozen saline soil, but also can describe the effect of RPSA on the mechanical and deformation behaviors of frozen soil. 

This study has been published in the International Journal of Mechanical Sciences in an article entitled “A bounding surface model for frozen sulfate saline silty clay considering rotation of principal stress axes”.