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首页> 外文期刊>International Journal of Mechanical Sciences >Experimental and numerical studies on compression-shear behaviors of brittle rocks subjected to combined static-dynamic loading
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Experimental and numerical studies on compression-shear behaviors of brittle rocks subjected to combined static-dynamic loading

机译：脆性岩体脆性岩体压缩剪切行为的实验性和数值研究

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The compression-shear behavior and failure mechanism of rocks under combined static-dynamic loading are of essential importance for mechanical characterization and construction safety in deep underground engineering applications. An inclined cylinder specimen is designed using a split Hopkinson pressure bar (SHPB) apparatus modified with an axial pressure chamber for laboratory studies. Specific issues on the validity of this compression-shear specimen that were not addressed previously have been numerically assessed involving the dynamic equilibrium of force and moment, stress uniformity, and interfacial friction effects. Experiments are conducted at different loading rates ranging from 500 to 4000 GPa/s and under axial pressures of 7, 21, 35, 49, and 63 MPa. Experimental results verify the dynamic equilibrium of inclined specimens in the axially constrained SHPB tests using pulse shaping techniques, which validates the data processing method newly proposed. Both the dynamic strength and total strength linearly increase with the loading rate. With the increasing pre-load ratio (ratio of the axial confining load to the unconfined compression strength of the tested material), the dynamic strength decreases, while the total strength increases and then keeps constant, where the turning point of the pre-load ratio approximates 0.7. High-speed photographs at a high loading rate illustrate that the increasing confinement can result in less shear but more tensile cracks. Particularly at a high confining condition, the inclined specimen fails by a feather-like shear fracture band where tensile secondary cracks extensively develop. The equivalent stress-strain relationships indicate the reinforcing effect of the confinement on the deformation and energy dissipation.
机译：静态负荷组合下岩石的压缩剪切行为和故障机理对于深层地下工程应用中的机械表征和建筑安全性是至关重要的。使用用轴向压力室修改的分裂霍普金森压力棒（SHPB）装置进行实验室研究设计倾斜圆筒样品。关于未解决的这种压缩剪切样本的有效性的具体问题已经在数值评估涉及动力和力矩，应力均匀性和界面摩擦效应的动态均衡。实验以不同的加载速率进行500-4000GPa / s，并且在7,21,35,49和63MPa的轴向压力下。实验结果验证了使用脉冲整形技术的轴向约束的SHPB测试中倾斜样本的动态平衡，这验证了新提出的数据处理方法。动态强度和总强度都随装载速率线性增加。随着载荷比率的增加（轴向限制负荷与测试材料的非束缚压缩强度的比率），动态强度降低，而总强度增加然后保持恒定，其中转折比的转折比近似0.7。高装载速率的高速照片说明了增加的限制可能导致较少的剪切但更拉伸裂缝。特别是在高限制条件下，倾斜标本通过羽毛状剪切断裂带，其中拉伸二次裂纹广泛发展。等效应力 - 应变关系表示限制对变形和能量耗散的增强效果。

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