State Key Laboratory of Frozen Soils Engineering Northwest Institute of Eco-Environment and Resources CAS Lanzhou Gansu 730000 China;
State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining and Technology Xuzhou Jiangsu 221116 China;
Da Xing''anling Observation and Research Station of Frozen-Ground Engineering and Environment Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Jiagedaqi Heilongjiang 165000 China;
frozen soil; hollow cylinder apparatus; intermediate principal stress coefficient; failure criterion; directional;