轴向及环向变形加载控制方式对花岗岩力学及声发射特性影响的试验研究

    EXPERIMENTAL STUDY ON THE INFLUENCE OF AXIAL AND CIRCUMFERENTIAL DEFORMATION LOADING CONTROL MODES ON THE MECHANICAL AND ACOUSTIC EMISSION CHARACTERISTICS OF GRANITE

    • 摘要: 加载控制方式是影响岩石力学性质重要因素之一。采用轴向变形控制和环向变形控制两种加载方式,对花岗岩试样开展变形速率为0.005·s-1条件下的单轴压缩试验,分析两种加载控制方式对花岗岩强度、应力及应变门槛值、能量演化及声发射特性等的影响规律。结果表明,与环向变形控制方式相比,轴向变形控制加载条件下:试样的峰值强度、损伤应力、起裂应力分别高12.8%、15.1%、13.1%;峰值轴向应变、损伤轴向应变及起裂轴向应变分别大12.5%、14.3%、15.2%,而峰值环向应变、起裂环向应变分别小24.2%、16.7%;峰值总能量大23.9%,储能能力Re大2.6%;声发射累计计数及累计能量分别高48.8%、106.1%,声发射b值大14.1%;通过声发射AF-RA值分析发现,两种加载控制方式对裂纹类型的影响不显著。研究结果对于深入揭示脆性岩石破裂机制具有重要意义。

       

      Abstract: The loading control mode is one of the key factors affecting the mechanical properties of rocks. In this study, two loading control modes—axial deformation control and circumferential deformation control—were used to conduct uniaxial compression tests on granite specimens at a deformation rate of 0.005·s-1. The effects of different loading control modes on the mechanical and acoustic emission(AE)characteristics of granite were explored. The influence of these modes on peak strength, stress and strain thresholds, energy evolution, and AE characteristics of granite was analyzed. The results show that the peak strength, crack damage stress, and crack initiation stress of specimens under axial deformation control are 12.8%, 15.1%, and 13.1% higher, respectively, compared to those under circumferential deformation control. The peak axial strain, axial damage strain, and crack initiation axial strain are 12.5%, 14.3%, and 15.2% larger, respectively, while the peak circumferential strain and crack initiation circumferential strain are 24.2% and 16.7% smaller, respectively. The total energy is 23.9% higher, and the energy storage capacity(Re) is 2.6% greater under axial deformation control. Furthermore, the cumulative count and cumulative energy of acoustic emissions are 48.8% and 106.1% higher, respectively, and the AE b-value is 14.1% larger. Analysis of the AE AF-RA value indicates that the two loading control modes do not significantly affect the fracture type of the samples. These research findings are of great significance for further understanding the fracture mechanism of brittle rocks.

       

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