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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.
Studying the dynamic mechanical properties of frozen soils is of great significance for artificial freezing construction of underground engineering, etc. In this paper, the mechanical properties of frozen soil subjected to uniaxial dynamic loading are studied using split Hopkinson pressure bar (SHPB) 8, -13, -17, -23 and -28 ℃ for a total of 6 negative temperature of the frozen soil, the strain rate range of 350 ~ 1200s-1 obtained under the corresponding conditions of frozen soil stress-strain relationship of frozen soil uniaxial dynamics The stress-strain curve has the characteristics of brittleness.It is found that the permafrost has the effect of temperature and strain rate, the strength of which increases with the decrease of temperature and strain rate, and the ultimate strain increases with the increase of strain rate.The lower the temperature of permafrost, the strain rate The higher the strain rate is, the more obvious the temperature effect is in the frozen soil.The viscoelastic damage constitutive model proposed in this paper can well describe the stress-strain relationship of six frozen soils.