东天山隧道Ⅳ级围岩大断面隧道全断面施工技术

Full-Section Construction Technology of Large-Section Tunnel of Grade Ⅳ Surrounding Rock in East Tianshan Tunnel

以新疆哈密东天山隧道左洞出口段为施工背景,对Ⅳ级围岩下大断面隧道的全断面施工方法进行了研究,优化了爆破参数,降低了爆破振动,减少了围岩损伤,实现了安全快速初支,通过现场试验及试验效果分析,得到了适合现场的安全、快速施工方法。研究结果表明:采用钻爆法施工时,对中风化、微风化凝灰质砂岩的Ⅳ级围岩大断面、全断面爆破法隧道成形质量好,与台阶法、中隔壁法(CD法)和交叉中隔壁法(CRD法)相比,简化了工序,降低了循环时间,提高了施工速度,保持了隧道自承能力,实现了全断面初支一次成型,经济、社会效益明显,更加适合现场实际,同时为类似工程提供了参考与借鉴实例。

Based on the construction of the left tube exit section of the East Tianshan Tunnel in Hami of Xinjiang Autonomous Region,a full-section construction method for the large cross-section tunnel in rock of gradeⅣis studied.The blasting parameters are optimized,the blasting vibration is reduced,the surrounding rock damage is decreased,and a rapid initial security support is achieved.Through field tests and analysis of test results,a safe and rapid construction method suitable for the site is achieved.The results of the study indicate that when the drilling and blasting method is used,the quality of tunnels formed by full-section blasting is good for large sections of GradeⅣsurrounding rocks of moderately weathered and slightly weathered tuffaceous sands.Compared with the bench method,the middle wall construction method(CD method)and the center cross diagram(CRD)method,the process is simplified,the cycle time is reduced,the construction speed is improved,and the self-supporting capacity of the tunnel is maintained.The method realizes a complete molding of the first branch,which has obvious economic and social benefits,and is more suitable for the actual situation of the site.At the same time,it provides reference examples for similar projects.