全长粘结岩锚抗拔受力特性

根据锚杆与锚固浆之间界面耦合机理,分析了岩锚抗拔状态下界面剪应力的分布特征。基于变形协调得出小荷载情况下界面剪应力随离锚固受力点距离的增大成指数衰减,并随荷载增加,界面出现4个变形段,分离段和残余变形段随着塑性区开展产生非耦应力向远端传递。耦合区界面剪应力分布与小荷载情况不同,其相关模量参数可采用综合折减系数表示。同时,提出了单孔多锚杆受力剪应力衰减模型,并通过试验证示了现场锚杆在荷载逐级加大时,剪应力峰值强度的变化规律。

Mechanical Characteristics of Fully Grouted Rock Bolts Under Axial Tensile Load

Based on the mechanical coupling at the interface between the bolts and the grout medium, an analytical model is developed for fully grouted rock bolts under tensile load. The shear stress of the interface attenuates exponentially with the increasing distance from the point of loading when the deformation is compatible and the bolts are flexible. Decoupling may start at the loading point with the applied load increasing and then propagate towards the far end of the bolt. Meanwhile, the analytical model may be modified by a factor to simulate the distribution of shear stress due to the changing modulus of loaded bolts, grout medium and rock. A case study with four bolts in one borehole confirm that the rock bolts in site have four shear sections, and it is also revealed that the peak shear strength changes with the distance fromloadingpoint, magnitude ofload and shear stress.