CCTEG Coal Mining Research Institute
State Key Laboratory ofIntelligent Coal Mining and Strata Control

锚杆安装预紧状态对其后续服役工况有重要影响。依托自主研发的锚杆力学性能综合试验台,以托盘垂直于杆体安装为例,对真实锚杆系统施加不同的预紧扭矩,测试安装预紧、轴向拉伸等静载阶段锚杆的力学响应特征,揭示杆体受力的转化机制,阐释安装工况对锚杆后续工况的影响规律。试验发现,杆体预紧力与预紧扭矩呈线性关系,杆体扭矩与预紧扭矩呈非线性关系。轴向拉伸阶段杆体扭矩持续降低,尤其以杆体弹性阶段、屈服阶段降幅最为明显,杆体强化阶段扭矩大致保持恒定。拉扭组合状态杆体的极限承载值降低,相当于杆材强度的89.65%~93%。预紧扭矩对杆体极限承载值几乎没有影响,但预紧扭矩的增加会导致极限承载点的杆体伸长量不断减小。其中,预紧扭矩450N·m时杆体延伸率较杆材降低2.2个百分点。对比各预紧扭矩方案的结果确定预紧扭矩的合理值为350N·m。力学分析发现,杆体残余扭矩产生的切应力是其承载能力及延伸率降低的主要原因,建议采用张拉预紧方式安装锚杆,以消除螺纹预紧摩擦产生的不利影响。

The pre-tightening state of rockbolt has a significant effect on its subsequent performance. Using a self-developed comprehensive experimental platform to assess the mechanical performance of rockbolts, taking the installation of the tray perpendicular to the bolt as an example, varying pre-tighte- ning torques are applied to the rockbolt system to compare the mechanical response during stages of pre- tightening installation and axial tension. The transformation mechanism of axial force on the bolt is re- vealed, and the influence of initial installation on the subsequent performance is explained as well. The experimental results show that there is a linear relationship between the pre-tightening force of bolt and pre-tightening torque, and a nonlinear relationship between the residual torque and pre-tightening torque. During axial tension stage, the residual torque of rockbolts continuously decreases, especially in the elas- tic and yield stages, where the reduction is most significant; while in the strengthening stage, the torqueremains roughly constant. The ultimate bearing capacity of bolts decreases in the combined tension- torsion state, equivalent to 89.65% - 93% of rockbolts material strength. Although the pre-tightening torque has almost no effect on the ultimate bearing capacity of rockbolts, its increase leads to a conti- nuous decrease in the elongation of the rockbotls at the ultimate bearing point. Notably, at a pre-tighte- ning torque of 450 N·m, the elongation rate of rockbolts decreases by 2.2 percentage points compared to the base material. Compared the results of different testing schemes, a reasonable value for pre-tightening torque is determined to be 350 N·m. Mechanical analysis shows that the shear stress generated by the re- sidual torque is the main reason for the reduction in its bearing capacity and elongation. It is recommen- ded to pre tighten rockbolts to eliminate the adverse effects caused by pre-tightening friction at rockbolts tail threads.

国家自然科学基金项目(52274123,52274085);开采研究院科技创新基金项目(TDKC-2022-MS-01,TDKC-2022-QN-02)