软弱围岩浅埋隧道全长黏结砂浆与水泥基药卷锚杆的锚固效果对比研究

摘要

铁路隧道锚杆主要有2种锚固方式:全长黏结砂浆和水泥基药卷,前者施工质量较好,可加固杆体周围岩体,后者施工简便,能快速发挥作用,在现有施工工艺的前提下,为了比较全长砂浆与水泥基药卷这2种锚固剂在浅埋软弱破碎围岩中的锚固效果,以郑万高铁许良隧道为依托工程,采用现场试验的方法对全长砂浆锚杆与水泥基药卷锚杆的锚固效果问题进行研究,选取V级围岩段分别设置全长砂浆锚杆段50m与水泥基药卷锚杆段50m进行对比试验,且改善了全长砂浆锚杆注浆工艺,使其注浆密实度达到90％.对比试验的项目有:锚杆轴力、初支钢架应力、喷混凝土应力、水平收敛和拱顶沉降.现场实测结果表明:全长砂浆段的拱顶沉降和净空收敛在边墙锚杆施做后得到了更好的控制,得益于注浆工艺的先进性及后期强度的迅速提高,全长砂浆锚杆受力较大,且使喷射混凝土和钢架受力较均匀.相比之下,水泥基药卷段的围岩变形持续发展,受限于锚固质量及后期强度的不足,水泥基药卷锚杆受力较小,导致喷射混凝土和钢架承担较大部分的围岩压力,且不均匀.结论:在当前施工工艺和地质条件下全长黏结砂浆锚杆锚固效果较好.%There are two methods of anchoring bolt in railway tunnel construction:full grouting and concrete-based cartridge.The former has a better quality of construction and can consolidate the rock mass around the bolt,and the latter can be easily applied and come into play very quickly.To compare anchoring effect between full grouting bolt and concrete-based cartridge bolt in sallow-buried fractured rock mass on the premise of current construction technology,the paper adopts the method of field test to study the anchoring effect between fully grouted bolt and concrete-based cartridge bolt based on Xuliang tunnel on Zhengzhou-Wanzhou high-speed railway.The test selects two sections of 50m in length to product contrastive analysis,where the rock mass is V level and the grouting technology is improved so that the saturation of full grouted bolt could be 90％ or more.The contrastive items include the axis force of bolt,the stress of steel framework and shotcrete of primary support,horizontal convergence and crown settlement.The site monitoring results show that the horizontal convergence and crown settlement in the section of fully grouted are effectively controlled after the installation of bolt in side wall due to the advanced grouting technology and quickly increased strength in later period;the full grouted bolt undertakes more load,and the stress of shotcrete and steel framework is distributed uniformly.In contrast,the deformation of rock mass in the section of concrete-based cartridge develops continuously,and the bolt in the section of concrete-based cartridge undertakes less load due to the restriction of anchoring quality and insufficient strength in later period,resulting in shotcrete and steel framework taking most and non-uniform stress.It is concluded that the anchoring effect of full grouting bolt is better than that of the concrete-based cartridge as far as the current geological condition and construction technology are concerned.