引江济淮软岩钢筋、GFRP筋锚杆承载差异试验

Experiment on the difference of load bearing of GFRP and steel bars in soft-rock slopes of water diversion from Yangtze to Huai

引江济淮试验工程采用锚杆加固河道软岩边坡。通过对钢筋、玻璃纤维增强聚合物(GFRP)筋锚杆实施现场拉拔试验以及锁定观测试验,研究钢筋和GFRP筋锚固性能差异。研究结果表明,试验软岩边坡下,GFRP筋锚杆承担的极限荷载大于钢筋锚杆,具有更高的界面黏结强度,GFRP筋锚杆为杆体拉断破坏,钢筋锚杆为杆体拔出破坏;GFRP筋锚杆的有效锚固长度小于钢筋锚杆,GFRP筋杆体轴力沿深度衰减速率大于钢筋锚杆,GFRP筋锚杆与胶结体具有更好的变形协调性;GFRP筋锚杆的预应力衰减率小于钢筋锚杆,锚杆预应力衰减缘自于界面黏结蜕化,围岩扰动对锚杆预应力衰减有直接影响;GFRP筋锚杆的锚固性能优于钢筋锚杆,界面黏结状态出现蜕化的剪应力水平高于钢筋锚杆。

A soft rock slope in the testing project of water diversion canal from Yangtze to Huai is reinforced with the reinforcement bars. The pullout experiment and stress relaxation test on glass fiber reinforced polymer（GFRP） bars and steel bars were carried out in the field in order to investigate the difference of anchoring performance between the GFRP bars and steel bars. The test results show that the ultimate bearing capacity of the GFRP bar is higher than that of the steel bar in soft rock slope. The GFRP bar has higher bond strength at interface than the steel bar. The GFRP bar deformed by breaking off above the grouted zone,whereas the steel bar was pulled out of the rock under the pulling force. The effective anchorage depth of the GFRP bar is shorter than that of the steel bar,and the axial force in GFRP bar degrades faster along the depth compared to that of steel bar. Compared to the steel bar,there is better deformation coordination between the GFRP bar and the grout,i.e.,the grout deformed together with the GFRP bar. The pre-stress attenuation rate of the GFRP bars is less than that of the steel bars. The pre-stress attenuation of the bars is due to the degradation of interface bond. The disturbance of the surrounding rock has also a direct effect on the pre-stress loss. The anchorage performance of the GFRP bar is better than that of steel bar,and its shear stress level is higher than that of steel bar when the interface bond degrades.