To fully study the strength characteristics of frozen clay under complex stress paths such as the variation of principal stress axis direction

a series of different principle stress direction shear experiments were carried out using the frozen soil hollow cylinder apparatus at a temperature of -10 ℃ to investigate the influence of the major principal stress orientation angle a (defined in the vertical plane)

the intermediate principal stress ratio b and the mean principal stress p on the strength characteristics of frozen clay. Analyzing the generalized shear stress-generalized shear strain curves

the results showed that the strength of frozen clay was great influenced by the changes in a angle and p-value

and it was not affected by the changes in b-value. The failure strain was affected by the changes in these three parameters. The styles of stress-strain curves were all elastic-plastic strain harden curves and the range of elastic strain of the curves was about 0.5%

which was not affected by different stress paths. The strength model of frozen clay under different principle stress direction shear experiments was built through analyzing the relationship between stress and strain. Moreover

the relationship about generalized shear modulus EJt and strain was obtained

and the influence of initial shear modulus EJt0 on EJt-strain curves was also discussed. The threshold value of EJt0 was found and was about 6×105 kPa for frozen clay. The changes in a angle

b-value and p-value had great influence on the strength characteristics of frozen clay.