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单轴压缩下裂隙砂岩宏细观损伤破坏特性的试验研究
Experimental study on the damage characteristics of macro-meso damage in fractured sandstone under uniaxial compression
投稿时间:2023-08-01  修订日期:2023-09-17
DOI:
中文关键词:  裂隙砂岩  单轴压缩  PFC2D数值模拟  力学性质  声发射  细观损伤
英文关键词:fractured sandstone  uniaxial compression  PFC2D numerical simulation  mechanical properties  acoustic emission  meso-damage
基金项目:国家自然科学基金项目
作者单位邮编
胡千庭 重庆大学 400044
余长君 重庆大学 400044
李全贵* 重庆大学 400044
钱亚楠 重庆大学 400044
凌发平 重庆大学 400044
刘荣辉 重庆大学 400044
李文禧 重庆大学 400044
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中文摘要:
      裂隙岩体影响岩土工程稳定性,开展裂隙岩体研究具有重要工程意义。首先在砂岩试样上设置不同角度的单一裂隙,采用室内单轴压缩试验从宏观角度研究了裂隙砂岩损伤破坏特性。结果表明,随着裂隙倾角α的增加,试样峰值强度和弹性模量均值逐渐增大,预制裂隙对试样力学性质的削弱作用减弱;预制裂隙降低了试样AE事件的活跃水平,AE事件在α为90°时最为活跃;AE能量幂律分布指数随着α增加呈现先增后减再增的“N”型变化趋势。其次利用PFC2D建立裂隙岩体数值模型,从细观角度揭示了裂隙砂岩破坏过程微裂纹扩展规律和损伤演化过程。试样加载过程中总裂纹和剪裂纹数量随着α增加呈增大趋势,而拉裂纹数量持续增加,试样破坏是以剪切破坏为主的拉剪混合破坏;裂隙试样细观损伤演化过程中,细观微裂纹最先由预制裂隙尖端处萌生然后扩展贯通至试样上下两端,细观损伤演化过程中的微裂纹数量呈带状分布,裂纹热点分布形式与室内试验宏观裂纹扩展模式基本相一致。
英文摘要:
      Fractured rock mass affects the stability of geotechnical engineering, and it is of great engineering significance to carry out research on fractured rock mass. Firstly, single cracks with different angles were set on sandstone samples, and the damage and failure characteristics of fractured sandstone were studied from a macro perspective by indoor uniaxial compression test. The results show that with the increase of crack dip angle α, the peak strength and elastic modulus of the sample increase gradually, and the weakening effect of prefabricated cracks on the mechanical properties of the sample is weakened. The prefabricated cracks reduce the activity level of AE events, and the AE events are most active when α is 90°. With the increase of α, the power-law distribution index of AE energy shows an “N” type change trend of increasing first, then decreasing and then increasing. Secondly, the numerical model of fractured rock mass is established by PFC2D, and the micro-crack propagation law and damage evolution process of fractured sandstone failure process are revealed from the mesoscopic point of view. The number of total cracks and shear cracks in the loading process of the sample increases with the increase of α, while the number of tensile cracks continues to increase. The failure of the sample is a mixed failure of tension and shear dominated by shear failure. In the meso-damage evolution process of the fractured specimen, the meso-microcracks are first initiated at the tip of the prefabricated crack and then extended to the upper and lower ends of the specimen. The number of microcracks in the meso-damage evolution process is distributed in a band, and the distribution of crack hot spots is basically consistent with the macro-crack propagation mode of the indoor test.
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