不同围岩条件下锚杆肋间距与锚固力优化研究

Optimisation of bolt rib spacing and anchoring force under different conditions of surrounding rock

为研究不同围岩条件下锚杆肋间距与锚固性能的关系,基于厚壁理论,对肋间距分别为12、24、36、48 mm的左旋螺纹钢锚杆锚固试件在套筒壁厚4.5 mm和6.0 mm条件下进行拉拔试验,通过测试拉拔力、拉拔力大于100 kN的位移量、套筒周向应变、耗能值等参数,探讨了不同围岩条件下锚杆肋间距与锚固性能的关系。试验结果表明:在不同的套筒中,即不同围岩条件下,随着肋间距的增加,锚杆拉拔力大于100 kN的位移量、套筒周向应变、拉拔耗能值相应增大;肋间距为24 mm时,锚杆拉拔力最大,相同肋间距的锚杆在围岩强度较大的条件下拉拔力较大;壁厚为4.5 mm的套筒周向应变均大于壁厚为6.0 mm的套筒,即不同围岩条件对锚杆控制其变形能力有重要影响;在不同围岩条件下,增大肋间距均可以提高锚杆的锚固性能。

This study investigated the relationship between bolt rib spacing and anchorage performance under different conditions of surrounding rock. Based on the thick-walled cylinder theory, pull-out tests were carried out on sinistral rebar bolt specimens with the spacing of 12, 24, 36, and 48 mm, which were anchored in the steel sleeves with wall thicknesses of 4.5 and 6.0 mm, respectively. Results of the drawing force, the displacement of drawing force more than 100 kN, the circumferential strain of the sleeves and energy dissipation were obtained. Experimental results show that the displacement of drawing force more than 100 kN, the circumferential strain and the energy dissipation value of the sleeve increase with increasing the rib spacing in different sleeves（different surrounding rock conditions）, respectively. The pulling force of anchor rod is found to be the highest when the rib spacing is 24 mm. While with the same rib spacing, the stronger the surrounding rock is, the larger the pulling force is. The circumferential strain of the sleeve with a 4.5 mm thick wall is larger than that of 6.0 mm, which indicates that the effect of surrounding rock is significant on the deformation ability of bolts. Moreover, the anchorage performance can be improved by increasing the rib spacing under different surrounding rock conditions.