新型拉压复合型锚杆锚固性能研究Ⅱ：模型试验

针对传统拉力型和压力型锚杆存在受力集中、锚固体与岩土体界面黏结强度发挥不充分、抗拔承载力偏低的问题,研发了一种新型拉压复合型锚杆。通过对传统锚杆及拉压复合型锚杆开展模型试验,对比研究了不同锚杆的极限抗拔承载力及其锚固性能。结果表明：拉压复合型锚杆极限抗拔承载力比传统拉力型锚杆大幅提高,拉压长度比为1∶2和2∶1时,分别提高79%和161%,且具有更好的位移延性和抗变形能力;拉压复合型锚杆峰后残余抗拔承载力显著提高,传统拉力型和压力型锚杆稳定残峰比最大值均不超过0.40,锚头相对拔出变形ξ_s=2.5%时,残峰比平均值分别为0.292和0.259;TC360-12锚杆和TC360-21锚杆稳定残峰比最小值分别不低于0.45和0.60,ξ_s=2.5%时,残峰比平均值分别为0.545和0.790;拉压长度比为2∶1的拉压复合型锚杆即将破坏时,受拉锚固段和承压锚固段协同承载能力更强,界面黏结强度得到充分发挥,锚杆极限抗拔承载力更高。

Analysis of anchorage performance on new tension-compression anchorⅡ: model test

The new tension-compression composite anchor (TC-anchor) is developed to overcome the shortcomings of the traditional tensile-type anchor (T-anchor) and pressure-type anchor (C-anchor), such as stress concentration, insufficient bonding strength between anchorage body and soil mass, and low uplift bearing capacity. The ultimate uplift bearing capacity and anchorage performance are analyzed comparatively based on the model tests for T-anchor, C-anchor and TC-anchor. The results show that, in contrast with T-anchor, the ultimate uplift bearing capacities of TC-anchor significantly increase by 79% and 161% respectively for the tension-compression anchorage length ratios (TCAL-ratio) of 1:2 and 2:1. The TC-anchor has better displacement ductility and deformation resistivity, and its residual uplift bearing capacity increases significantly. The maximum ratios of the residual uplift bearing capacity to the ultimate one (RU-ratio) of T-anchor and C-anchor are both not more than 0.40, with the average values of 0.292 and 0.259 for relative out deformation of anchor head ξ_s=2.5%. The tension and compression anchorage segments of TC-anchor with TCAL-ratio of 2:1 have stronger coordination-bearing capacity. When the TC-anchor is closed to failure, the bonding strength between grouting body and concrete failure plays sufficiently. So the ultimate uplift bearing capacity of TC-ancor with TCAL-ratio 2:1 is higher.