Abstract Underground rock structures are frequently subjected to water erosion and dynamic disturbance simultaneously. Herein, in order to study the coupled effects of water and high strain rate on the mechanical behavior and microstructures of sandstone, we conducted a series of dynamic unconfined compressive tests on oven-dried and water-saturated sandstone core samples using a split Hopkinson pressure bar. Test results revealed that, three macroscopic final patterns, namely unbroken, axial split and pulverization, were observed. At given strain rates, the presence of water weakens the dynamic peak stress and the dissipated energy density (the ratio of energy dissipation to residual axial strain) of rock sample but enhances the elastic modulus regardless of the failure pattern. Additionally, the saturated sample owns a higher rate dependence of dynamic strength compared to the dry one under the explored range of strain rate (43.9–156.7 s−1), which indicates that water-weakening on rock strength gradually attenuates with the increase of strain rate. Interestingly, thin sections analysis microscopically showed that the failure of dry samples is characterized by the intra-granular fracturing in larger quartz grains while that of saturated samples by the inter-granular fracturing. The underlying mechanisms were interpreted with two micro-mechanical damage models.

中文翻译：

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含水饱和度对砂岩动力行为和微观结构损伤的影响：现象和机制

摘要 地下岩石结构经常同时受到水蚀和动力扰动。在此，为了研究水和高应变率对砂岩力学行为和微观结构的耦合影响，我们使用分裂霍普金森压力棒对烘干和水饱和的砂岩岩心样品进行了一系列动态无侧限压缩试验。 . 测试结果表明，观察到三种宏观最终模式，即未破碎、轴向分裂和粉化。在给定的应变率下，水的存在削弱了岩石样品的动态峰值应力和耗散能量密度（能量耗散与残余轴向应变的比率），但无论破坏模式如何，都会提高弹性模量。此外，在探索的应变速率范围（43.9-156.7 s-1）下，饱和样品与干燥样品相比具有更高的动态强度速率依赖性，这表明随着应变速率的增加，水弱对岩石强度的影响逐渐减弱。有趣的是，显微镜下的薄片分析表明，干样品的破坏以较大石英颗粒的粒内破裂为特征，而饱和样品的破坏则以粒间破裂为特征。用两个微机械损伤模型解释了潜在的机制。显微切片分析表明，干样品的破坏以较大石英颗粒的粒内破裂为特征，而饱和样品的破坏则以粒间破裂为特征。用两个微机械损伤模型解释了潜在的机制。显微切片分析表明，干样品的破坏以较大石英颗粒的粒内破裂为特征，而饱和样品的破坏则以粒间破裂为特征。用两个微机械损伤模型解释了潜在的机制。