岩桥渐进弱化的Jennings抗剪强度准则

Modified Jennings shear strength criterion based on mechanical weakening model of rock bridges

Jennings抗剪强度准则以节理和岩桥抗剪强度参数按连通率加权平均的方式求取非贯通节理岩体的峰值抗剪强度,未考虑直剪试验过程中岩桥力学参数逐步弱化的影响,计算所得的抗剪强度与直剪试验结果存在较大偏差。基于人工齿状共面非贯通节理岩体的直剪试验,采用以剪切位移为变量的岩桥弱化度模型考虑岩桥力学参数弱化对抗剪强度的影响,提出改进的Jennings抗剪强度准则。考虑岩桥力学参数弱化的Jennings抗剪强度准则的计算结果更为接近试验值,表明考虑岩桥力学性质弱化是合理的。

Many theoretical criterions have been proposed to predict the shear strength of intermittent joints,of which the Jennings criterion is widely used.In Jennings criterion,the mechanical parameters of joint and rock bridge are simply averaged by a weight coefficient called connectivity rate to calculate the peak shear strength.The main limitation of Jennings shear strength criterion is that it cannot consider the mechanical weakening of rock bridges during the shear tests.The theoretical results by Jennings criterion are usually not consistent with the measured ones.A modified criterion is put forward.The modified criterion can overcome the limitations because it takes the mechanical weakening model of rock bridges.The results show that the predicted values by the modified Jennings criterion is closer to the measured data,compared to the original Jennings criterion,which indicates that the new criterion is better.Finally,the limitations of this new strength criterion are also analyzed.