冻土单轴动态加载下的力学性能

研究冻土的动态力学性能对于地下工程人工冻结法施工等具有重要意义。本文应用分离式霍普金森压杆(SHPB)，研究了冻土单轴动态加载下的力学性能，涉及-3、-8、-13、-17、-23和-28℃共6个负温的冻土，应变率范围350～1200s-1。获得了相应条件下的冻土应力应变关系。冻土的单轴动态应力应变曲线具有脆性特征。发现冻土具有温度和应变率效应，其强度随温度降低和应变率增大而增大，最终应变随应变率增大而增大。冻土温度越低，应变率敏感性越强；加载应变率越高，冻土的温度效应越显著。文中提出的粘弹性损伤型本构模型能够较好的描述6个温度冻土的应力应变关系。

Mechanical Behavior of Frozen Soil with Uniaxial Dynamic Loading

Investigation of dynamic behavior of frozen soil is of great importance to artificial ground freezing method in underground engineering, etc. In this article, split Hopkinson pressure bar (SHPB) is employed to investigate the dynamic character of artificial frozen soil under uni-axial stress condition. Tests are conducted at the temperature of -3, -8,-13,- 17,-23 and -28℃ and strain rates from 300 to 1200s-1. The stress-strain curves at different conditions were obtained. The uni-axial stress-strain curves of frozen soil show brittle character. The compressive strength of frozen soil shows positive strain-rate and negative temperature sensitivity，and the final strain of frozen soil shows positive strain-rate sensitivity over the range of strain rates and temperature employed. The thermal effect of frozen soil is greater with higher loading strain rates. The strain rates sensitivity of frozen soil is higher with lower temperature. The viscoelastic damage model mentioned in this article can describe the stress strain relation of frozen soil under dynamic loading.