中文摘要：

为研究主动围压状态人工冻结砂土的动态力学性能,利用直径50 mm变截面分离式霍普金森压杆试验装置,以取自山东济宁某矿-94.52 m处冻结砂土为研究对象,对长径比为0.5的冻结砂土试件进行主动围压状态下的冲击压缩试验,分析了主动围压和应变率对冻结砂土动态力学性能的影响。研究结果表明,无围压状态下,冻结砂土动态应力-应变曲线可分为弹性阶段、塑性阶段、黏性阶段和破坏阶段,冻结砂土呈脆性破坏;主动围压状态下,应力-应变曲线塑性阶段明显增长,无黏性阶段,冻结砂土呈微裂破坏。相同条件下,主动围压状态下冻结砂土的动态抗压强度均高于无围压状态,且随着围压的增大,动态抗压强度逐渐增大;当应变率为220 s~（-1）,温度为-15℃时,主动围压为0.5、1.0、1.5、2.0 MPa的动态抗压强度为无围压状态下的119%、140%、158%和181%。不同主动围压下的应力-应变曲线表现出汇聚现象,汇聚点趋向于无围压状态。冻结砂土的动态抗压强度随应变率的提高而增加。

英文摘要：

Dynamic compression tests were carried out to investigate dynamic properties of artificial frozen sand under active confining pressure. In the experiments, a variable cross-section split Hopkinson pressure bar（SHPB） apparatus with a diameter of 50 mm was employed. Frozen sand was sampled from-94.52 m level at a coalmine in Jining, Shandong province, and the ratio of length to diameter of the cylindrical frozen sand specimen was 0.5. The influence of confining pressure and strain rate on dynamic properties for artificial frozen sand was analyzed as well. The results show that under uniaxial loading condition, the stress-strain curve can be divided into four stages, i.e., elastic stage, plastic stage, viscous stage and failure stage. Moreover, the corresponding failure mode is brittle. However, under confining pressure, the plastic stage has been extended, there is no viscous stage and crack failure occurred. Dynamic compressive strength of artificial frozen sand under confining pressure is greater than that under uniaxial loading condition, and increases with the increase of confining pressure. When the strain rate is 220 s~（-1） and the temperature is -15 ℃, under the confining pressures of 0.5 MPa, 1.0 MPa, 1.5 MPa and 2.0 MPa, dynamic compressive strengths are 1.19, 1.40, 1.58 and 1.81 times that under uniaxial loading condition, respectively. Strain convergence phenomenon occurs under different confining pressure conditions, and the convergence position tends to uniaxial loading condition. The dynamic compressive strength increased with the increase of strain rate.