拉剪作用下节理岩体锚固力学分析模型

An analytical model of jointed rock bolts under the combination of tensile and shear loads

现有锚固理论不能反映节理岩体锚固的内在力学机制。基于节理岩体全长黏结型锚杆锚固的地质变形特征,根据加锚节理岩体超静定梁模型,将超静定梁转化为受到挤压分布力、轴力和剪切力共同作用的静定梁模型,探讨拉剪作用下节理岩体锚固的受力与变形的演化规律。基于结构力学理论,考虑锚杆横向剪切变形段荷载与变形的内在物理关系、位移相互协调关系以及由能量原理导出的平衡关系,建立拉剪作用下节理岩体锚固的力学分析模型,进一步提出拉剪荷载作用下的节理面一侧锚杆横向剪切变形段长度的计算方法。研究表明,加锚节理岩体受锚杆轴向拉力和销钉效应共同作用,节理面处锚杆轴力和剪力呈抛物线耦合关系;锚固角越大,锚杆销钉效应越显著。节理面一侧锚杆横向剪切变形段的长度随锚固角的增加而增大,但锚杆抗力随锚固角的增加而降低。与试验数据的对比分析表明,理论模型的计算结果与试验结果吻合较好,验证了该模型的合理性。研究结果可为节理岩体锚固研究及工程应用提供参考。

Current bolting theories without considering rock bolts. In this paper, the mechanical characteristics the dowel effect fail to reveal the mechanism of jointed of jointed rock bolts were discussed, and the transverse section of shear deformation of a jointed rock bolt was considered as a beam to establish the structural mechanical model. The load and deformation compatibility relationships of the transverse shear length were deduced. Based on the structural mechanics and the principle of minimum potential energy, an analytical model of jointed rock bolts was developed and an algorithm for calculating the transverse shear length on one side of the joint plane was proposed. It is revealed that the resistance of a jointed rock bolt is provided by the combination of the axial and shear forces, which act at the intersection of the bolt and joint. The resistance obeys a parabolic relationship. The larger the bolting angle, the greater the dowel effect. With increasing the bolting angle, the transverse shear length increases, but the resistance of the bolt decreases. Comparisons between the developed model and the experimental data were performed. It is shown that the proposed method agrees well with the experimental data and is thus proved to be reasonable and reliable.