考虑节理粗糙度的锚固节理岩体剪切试验

Shear Test of Bolted Joint Rock Masses Considering Joint Roughness

为研究粗糙度对锚固节理岩体剪切特性及锚杆抗剪作用的影响,提出了基于Synfrac软件与3D雕刻技术的岩石节理面三维重构方法,开展了不同节理粗糙度系数(JRC值)和不同法向应力下的锚固节理岩体剪切试验,研究了节理面剪胀效应对锚杆轴力、变形与破坏模式的影响,并在静力分析的基础上提出了考虑节理剪胀的锚杆抗力公式。试验结果表明:随着JRC值的增加,节理的剪胀效应使锚杆的轴向变形增大,从而使锚杆发挥出更大的轴力,提高了锚杆对节理面的剪切强度贡献(锚杆抗力);锚杆轴力增大的同时使锚杆从拉剪破坏模式转变为拉弯破坏模式。根据试验结果,在静力分析的基础上,引入了巴顿公式中的剪胀角,提出了考虑JRC值和法向应力的锚杆抗力公式,公式预测结果与试验结果吻合良好,平均相对误差为7.6%。

To study the influence of roughness on the shear characteristics of bolted joint rock masses and the shear resistance of bolts, a three-dimensional reconstruction method for rock joint surfaces based on Synfrac software and three-dimensional carving technology was proposed. A shear test of a bolted joint rock mass under different joint roughness(JRC) values and different normal stresses was conducted. The influence of the joint dilatancy effect on the axial force, deformation, and failure mode of the bolt was studied, and a resistance formula was proposed considering joint dilatancy based on static analysis. The experimental results show that, with the increase in JRC, the dilatancy effect of the joint increases the axial deformation of the bolt, so that the bolt exerts a greater axial force, and increases the contribution of the shear strength(bolt resistance) that bolts to the joint surface. When the axial force of the bolt increases, the bolt changes from a tension-shear failure mode to a tension-bending failure mode. Based on the experimental results, the dilatancy angle in the Barton formula was introduced based on the static analysis, and a bolt resistance formula considering JRC and normal stress was proposed. The predicted results of the formula were in good agreement with the experimental results, and the average relative error was 7.6%.