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对含单裂隙岩石开展单轴压缩试验,采用PIV粒子成像测速系统实时采集试验过程中岩样照片,借助PIVProcess流场处理系统将照片转为位移矢量。基于有限元原理计算应力,提出以应力集中强度比k的变化规律划分裂隙岩石变形破坏过程的方法,分析裂隙岩石变形破坏各阶段应力场特征。研究结果表明,加载过程中k随着轴向应变的增加呈现增大-稳定-波动-持续增大的变化规律,根据k变化规律,获得几个重要应力阀值即闭合应力σ_(cc)、起裂应力σ_(ci)、损伤应力σ_(cd)值分别为(0.13~0.17)σ_p、(0.48~0.59)σ_p和(0.80~0.92)σ_p(σ_p为峰值应力);k波动变化结束后,急剧增大,宏观裂纹在应力集中区域出现;应力集中区域与宏观裂纹分布区域具有较好的一致性。研究结果有助于提升人们对岩石应力场变化的认识,为裂隙岩石破坏过程阶段划分的研究提供一个新方法。
Uniaxial compression tests were carried out on rocks with a single fracture. PIV particle imaging velocimetry system was used to collect the rock specimen during the test in real time. The PIVProcess flow field processing system was used to convert the photos into displacement vectors. Based on the finite element method, stress is calculated and a method of dividing the deformation and failure of fractured rock by the variation of stress concentration ratio k is proposed. The stress field characteristics at different stages of deformation and failure of fractured rock are analyzed. The results show that k increases with the increase of axial strain in the process of loading, which shows the increasing regularity. According to the variation of k, several important stress thresholds, namely the closure stress σ_ (cc) The fracture stressσ_ (ci) and the damage stressσ_ (cd) were (0.13 ~ 0.17) σp, (0.48 ~ 0.59) σp and (0.80 ~ 0.92) σp (σ_p are the peak stress) It increased sharply and macroscopic cracks appeared in the stress concentration area. There was a good consistency between the stress concentration area and the macroscopic crack distribution area. The results of this study will help to raise people’s awareness of the changes of rock stress field and provide a new method for the study of the division of stage of rock failure process.