Frozen soil, widely distributed on the Earth, is composed of solid mineral particles, ice inclusions, liquid water and gaseous inclusions. The mechanical properties of frozen saline sandy soil is complicated due to its complex components and sensitivity to salt content and confining pressure. 

With the fast development of artificial ground freezing, engineers have to face engineering difficulties with the appearance of frozen saline soil. Thus, there is an urgent need to study the constitutive response of frozen saline soil to describe the mechanical properties of frozen saline coarse sandy soil. 

Recently, a research group led by Prof. LAI Yuanming from the Northwest Institute of Eco-Environment and Resources (NIEER) of the Chinese Academy of Sciences explored the effects of particle breakage, pressure melting, shear dilation and strain softening or hardening on the frozen saline coarse sandy soil, to develop a phenomenological elastoplastic constitutive model of frozen saline sandy soil. 

Through a series of triaxial compression tests, engineers investigated frozen saline sandy samples with different Na₂SO₄ contents under different confining pressures, and observed a shear dilation phenomenon in the loading process of frozen saline soil. 

The test results indicated that the stress-strain curves exhibited strain softening/hardening phenomena when the confining pressures were below or above 6 MPa, respectively. With increasing confining pressure, the strength of frozen saline sandy soil firstly increased and then decreased. 

Besides, triaxial tests were conducted to reveal the particle breakage characteristics in the process of shearing. Based on the test results, a failure strength line considering the influences of soil particle breakage and ice melting is proposed. 

The study entitled "An elastoplastic constitutive model for frozen saline coarse sandy soil undergoing particle breakage" was published in Acta Geotechnica.