Abstract To study the influence of freeze-thaw weathering on dynamic tensile properties and damage mechanism of rock material, the porosity and T2 spectrum distribution of rock samples underwent different freeze-thaw cycles were obtained by nuclear magnetic resonance (NMR), and the variation of micropores and macropore that caused by freeze-thaw cycles were calculated by T2 spectrum and then analyzed. In addition, the dynamic splitting tensile test was carried out on rock samples by using split Hopkins pressure bar (SHPB), and dynamic tensile peak strength, Young's modulus and peak strain were gained and analyzed. Dynamic tensile strength degradation prediction model was established to predict the damage of rock caused by freeze-thaw weathering. Results show that the porosity of the rock sample increases with freeze-thaw cycles increase, the freeze-thaw damage on rock microstructure is mainly caused by the expansion of micropores into macropores, while the initiation of micropores is the secondary reason. With freeze-thaw cycles increasing, the peak strain increases, the dynamic Young's modulus decreases. In addition, the effect of freeze-thaw weathering deteriorates the rock's anti-deformation ability and durability.

中文翻译：

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冻融风化作用下花岗岩的动态劈裂拉伸试验

摘要 为研究冻融风化对岩石材料动态拉伸特性和损伤机理的影响，采用核磁共振（NMR）方法获得岩石样品孔隙度和T2谱分布，并得到不同冻融循环的岩石样品的孔隙率和T2谱分布，通过T2谱计算冻融循环引起的微孔和大孔，然后进行分析。此外，利用劈裂式Hopkins压力棒(SHPB)对岩样进行动态劈裂拉伸试验，获得并分析了动态拉伸峰值强度、杨氏模量和峰值应变。建立动态抗拉强度退化预测模型，预测冻融风化对岩石的破坏。结果表明，随着冻融循环次数的增加，岩石样品的孔隙度增加，岩石微观结构的冻融破坏主要是由微孔扩展为大孔引起的，而微孔的萌生是次要原因。随着冻融循环次数的增加，峰值应变增加，动态杨氏模量降低。此外，冻融风化作用使岩石的抗变形能力和耐久性变差。