非贯通节理Jennings强度准则的岩桥弱化和节理面起伏角修正

 通过对具有不同粗糙程度(以节理面起伏角表示)的共面非贯通人工节理进行不同法向应力水平下的直剪试验，研究节理面起伏角对非贯通节理剪切强度的影响，分析在剪切过程中岩桥力学参数的弱化机制。现有Jennings准则将岩桥视为完整岩块，计算所得的剪切强度与直剪试验结果存在较大偏差。在试验结果的基础上，考虑剪切过程中岩桥力学参数的弱化和节理面起伏角的影响，对Jennings准则进行修正。将修正Jennings准则计算的非贯通节理剪切强度结果与直剪试验结果对比，结果表明：修正Jennings准则的计算结果与试验结果吻合较好，能较好地预测具有规则起伏角的非贯通节理剪切强度。

MODIFICATION OF JENNINGS STRENGTH CRITERION FOR INTERMITTENT JOINTS CONSIDERING ROCK BRIDGE WEAKENING AND JOINT SURFACE UNDULATING ANGLE

The shear strength of intermittent joints in rock masses has an important influence on the stability of blocky rock system. For a single rock joint,the surface roughness is of paramount importance to its mechanical property,such as shear strength. Many theoretical criterions have been proposed to predict the shear strength of intermittent joints,of which the Jennings criterion is the most widely used one. However,in Jennings criterion,the mechanical parameters of joint surface and rock bridge are simply averaged by a weight coefficient called connectivity rate to calculate equivalent mechanical parameters and the surface roughness isn't taken into account. So the direct shear tests are carried out on artificial coplanar intermittent joints with different surface undulating angles under different normal stresses to investigate the influence of undulating angle on the strength of intermittent joint and analyze the mechanism of the weakening of rock bridge mechanical parameters. Based on the direct shear test data,modifications are made to the Jennings criterion by considering the weakening of the mechanical parameters of rock bridge and the surface undulating angle during shear process. And comparisons between the results computed with modified Jennings criterion and the shear test data are made to evaluate the effect of modification;it is shown that the calculated results according to the modified Jennings criterion agree well with the experimental data;and the modified Jennings criterion is able to predict the shear strength of the intermittent joints with regular surface undulating angle well.