Dynamic characteristics of warm frozen soil under direct shear test-comparison with dynamic triaxial test

A series of dynamic direct shear tests and triaxial tests were conducted to investigate the dynamic properties of the warm frozen soil along the Qinghai-Tibet railway. The relationship between dynamic shear stress and dynamic shear strain of frozen soil under relatively high negative temperature is given according to the test results. The influences of cooling temperature, vertical pressure, confining pressure and vibration time on both dynamic shear modulus and dynamic damping ratio are discussed. The test results indicate that the dynamic stress-strain relationship in warm frozen soil at different cooling temperatures can be described by Hardin-Drnevich constitutive model. The maximum dynamic shear modulus increases with decreasing cooling temperature and increasing vertical and confining pressures; however, it exhibited a slightly decreasing tendency with increase in vibration time. On the other hand, the maximum damping ratio decreases with decreasing temperature and increasing vertical pressure and confining pressure, but showed a minor increasing tendency with increasing vibration time. The multiple regression method was used to assess the relationships between dynamic parameters and influence factors.