岩石拉伸破坏机制与应力波谱特征
Damage mechanism and stress wave spectral characteristics of rock under tension
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摘要: 岩石材料的受拉性能远不及受压性能好,其受拉的破坏机制决定着岩石工程的稳定性与安全性。为研究岩石材料受拉损伤破坏机制,通过振动理论和间接拉伸条件下声发射试验分析花岗岩损伤演化过程,并通过分形理论以及声发射信号的主频和能量分布特征来获得拉伸破坏机理。从声发射事件分布来看,当加载应力达到抗拉强度时岩样瞬间破坏,声发射事件数急剧增大,反映出明显的脆性性能。声发射事件的分形维数也随着加载应力增大而减小。间接拉伸破坏全过程声发射信号的主频集中在175~250 kHz和50~100 kHz两个频率范围,声发射信号的能量集中分布在0~312.5 kHz频段,占信号总能量的80%以上。其拉伸应力波特征和分形机理能够反映岩石材料的基本力学性能,对更进一步研究岩石的性能、增强岩石工程的安全性有重要的实验和理论意义。Abstract: The tensile property of rock is much worse than its compression performance, and the damage mechanism under tension determines the stability and safety of rock engineering. To study the tensile damage mechanism of rock, the vibration theory and acoustic emission (AE) signal tests under indirect tensile conditions are used to analyze the damage evolution process of granite. The tensile damage mechanism is obtained by using the fractal theory and the distribution of dominant frequencies and energies of AE signals. Based on the distribution of AE events, damage is instantaneous and the number of AE events sharply increases when the loading stress reaches its ultimate tensile strength (UTS), reflecting apparently brittle performance. The fractal dimension of AE events decreases as the loading stress increases. The dominant frequencies of AE signals at the indirect tensile stage are mainly concentrated at 175~250 kHz and 50~100 kHz. Their energies are intensively distributed in the band width of 0~312.5KHz. The stress wave characteristics and fractal mechanism can reflect the basic mechanical property of rock. They are of important experimental and theoretical significance for further studies on rock performance and enhancing the safety of rock engineering.