The binary medium model hasbeen widely studied in unfrozen geomaterials

however

it is still not wellstudied for frozen soil. In order to investigate the strength-deformationcharacteristics of frozen silty sand in triaxial test

the binary medium theoryis introduced to interpret the stress-strain relationship of frozen soil. Thereare plenty of parameters for existing binary medium model

and thedetermination of parameters is with complexity. A binary medium model isproposed based on simplified breakage parameter. The triaxial tests of frozensoil were performed under five kinds of fine particle content and four kinds ofconfining pressure conditions

and the validity of proposed model was examinedby test results. It is revealed that the stress-strain relationship can bedivided into three stages with the increase of axial strain

namely

linearelasticity stage

elastoplastic stage

and strain softening stage. Based onbinary medium model

all three stages can be well explained by thetransformation theory of bonding element and friction element. Under theidentical confining pressure conditions

both deviatoric stress and the maximumvalues of bulk expansion decrease

while the shear strength decreases linearlywith the increase of fine particle content. Considering cross-section areacorrection

the silty sand with different fine particle contents presentssoftening characteristics

and the volume deformation shows the pattern from shrinkageto expansion with the increase of axial strain. The turning points of the three stages of deviatoricstress development are in good agreement with the extreme point of volumeshrinkage and the turning point of volume expansion. Comparingthe measured deviatoric stress in triaxial tests with the calculated by binarymedium based on simplified breakage parameter

it is believed that the proposedmodel is able to simulate the stress-strain relationship of frozen silty sandin triaxial tests.