节理特性对岩体力学性能的影响

来源期刊:中南大学学报(自然科学版)2016年第12期

论文作者:张国凯 李海波 夏祥 李娜娜 柴少波

文章页码:4198 - 4206

关键词:颗粒流;单轴压缩;节理特性;岩体力学参数;波传播

Key words:particle flow code; uniaxial compression; joint features; mechanical properties of rock mass; wave propagation

摘    要:采用颗粒流模拟研究单轴压缩下节理特性对试件宏观力学参数、能量及波传播规律的影响,揭示裂纹扩展演化机理及破坏模式的变化规律,定义细观节理刚度比和强度比反映节理力学特性。研究结果表明:峰值强度、弹性模量、起裂应力随节理厚度增加、刚度比的下降而不断减小,泊松比随节理厚度增加而大幅度增加,节理强度比直接影响峰值强度;与张开节理相比,节理充填物降低尖端应力集中,导致试件损伤破坏程度及破坏模式的改变,同时引起宏观力学参数增大,并随节理刚度减小,逐渐趋近前者。通过在模型内设置激发源和接收器,对激发源施加速度脉冲模拟剪切波和压缩波的传播过程,节理对波幅影响远大于波速,充填节理透射系数明显大于张开节理透射系数,前者随厚度增加衰减更快,与纵波相比,横波随节理弱化衰减较快。

Abstract: The uniaxial compression test was performed by particle flow code to study the influence of joint features on the macro mechanical properties, energy and wave propagation. Simultaneously, the mechanisms of crack evolution and failure modes were illustrated. Mesoscopic stiffness ratio and strength ratio were defined to reflect mechanical features of joint. The results show that with the increase of joint thickness and the decrease of joint stiffness ratio, ultimate strength, elastic modulus and crack-initiation stress all decrease. On the contrary, Poisson ratio increases a lot with the increase of joint thickness. However, joint strength ratio only has an effect on ultimate strength. Compared with open joint, joint fillings reduce the stress concentrations at joint tips and increase the macro mechanical parameters of specimens which gradually approach the former with the decrease of joint stiffness. These all lead to the changes of damage degree and failure modes. Numerical simulation of transverse and longitudinal wave propagation was implemented by setting a transmitter and receiver in the model and applying a velocity pulse to the transmitter. The effect of joint on the amplitude attenuation is much larger than wave velocity. The transmission coefficient of filling joint is much bigger than that of open joint. Compared with longitudinal wave, transverse wave produces more amplitude attenuation.

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