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| 不同加载条件下含裂隙岩石裂纹扩展特征及能量演化机制试验研究 |
| Crack Propagation and Energy Evolution Mechanism of Rock Containing Pre-existing Crack Under Different Loading Conditions |
| 投稿时间：2023-05-19 修订日期：2023-09-16 |
| DOI： |
| 中文关键词: 红砂岩、裂纹路径、应变率、力学性质、能量演化 |
| 英文关键词:red sandstone crack propagation strain rate mechanical property energy evolution |
| 基金项目: |
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| 中文摘要: |
| 以相同尺寸含裂隙红砂岩为静态、动态加载试验对象,采用液压伺服刚性压力机进行试样的单轴压缩试验,利用SHPB系统对试样进行冲击加载,配合摄像系统获得不同加载条件下试样裂纹扩展路径,得到相应静态、动态应力-应变曲线,对比分析静态加载、不同强度冲击加载条件下试样的裂纹扩展模式、压缩强度、能量特征。结果表明,试样裂纹萌生、发展及最终断裂模式与预制裂隙角度、应变率关系密切,与静载试样相比冲击动载试样出现了Ⅳ型拉伸-剪切混合裂纹、离层裂纹以及更多的远场裂纹；中应变率范围内,随应变率增加含预制裂隙岩样出现了由拉伸裂纹为主向X状剪切破坏的转变；试样压缩强度与裂纹扩展模式相关,试样吸收总能量与静态、动态单轴压缩强度近似呈线性关系,不同加载条件下45°试样压缩强度均为最低；静态加载条件下,不同产状预制裂纹的存在使试样储能极限、延脆性特征受到不同程度的改变；动态加载条件下,应变率越大,试样吸能越高,破碎耗能密度、能量耗散率越大,同时试样裂纹角度对破碎耗能密度和能量耗散率的影响越显著；相对静载条件,动载条件下试样破碎耗能密度的主要影响因素更加多样和复杂。 |
| 英文摘要: |
| Red sandstone with the same size containing pre-existing single crack was taken as the research object in static and dynamic loading tests. Hydraulic press was used for uniaxial compression experiment and SHPB was used for impact test. The corresponding static and dynamic stress-strain curves were obtained. The crack propagation of samples under different loading conditions were obtained with the camera system. The crack propagation, compressive strength and energy characteristics of samples under static loading and dynamic impact loading with different speeds were analyzed. The findings show that the crack initiation, development and final fracture mode of the samples are closely related to the angle of pre-existing crack and strain rate. Compared with samples under static loading, tensile and shear mixed cracks, layer separation cracks and more far-field cracks appeared in the samples under dynamic loading. With the increase of strain rate, the samples with pre-existing crack change from tensile crack to X-shaped shear failure in the range of medium strain rate. The compressive strength of the sample is related to the crack propagation. The total energy absorbed by the sample is approximately linear with the static and dynamic uniaxial compression strength. Under different loading conditions, the compressive strength of samples with 45°crack is the lowest. Under static loading, the pre-existing crack with different angles changed the energy storage limit and the characteristics of ductility and brittleness of samples. Under dynamic loading, the higher the strain rate, the higher the sample energy absorption, the higher the energy dissipation density and energy dissipation rate, meanwhile, the influence of crack angle on dissipated energy density and energy dissipation rate is more significant. Compared with static loading, the main influence factors of dissipated energy density under dynamic loading are more diverse and complex. |
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