700m深级公路隧道超大竖井掘进工法比选——以天山胜利隧道2-2竖井为例

Comparison and Selection of Excavation Methods for Super-Large Vertical Shafts in a 700 m Deep Highway Tunnel:A Case Study of 2-2 Shaft of Tianshan Shengli Tunnel

为解决700 m深级高寒高海拔地区高速公路大直径竖井施工前施工工法难以抉择的问题,考虑到新疆严苛的环保要求,天山复杂的工程地质,钻爆法与TBM法“3洞”组合洞内通风的迫切需求,以及施工条件、工期、成本控制等诸多因素,调研国内外不同行业、不同级别井深的井筒正井法、反井法、竖井钻井法及竖向掘进机法等掘进工法,从地质适应性、工期要求、场地条件、技术成熟度、安全性、环保、成本等方面进行综合比选,结合天山胜利隧道2-2竖井工程的经验,得出主要结论如下:1)正井法、反井法、钻井法在煤矿等其他行业技术成熟,设备市场齐全,而在高速公路隧道700 m深级超大竖井施工尚属首次,施工难度极大,应引起项目决策者高度重视;2)高速公路隧道700 m深级超大竖井施工前,再次进行渗透系数、涌水量、围岩岩性、强度、破碎带位置及长度等的详勘或校核,是进行方案比选的重要前提;3)采用钻井法对应充分考虑坚硬地层导致的成本增加和工期延长等不利后果;4)超大竖井掘进机掘进设备、技术尚处在探索阶段,会因设备制造周期长以及泥浆泵更换、垂直度纠偏、刀盘漏油修复、频繁换刀等问题带来的工期不确定性和成本大幅增加,采用竖向掘进机法应慎之又慎。

The construction methods for large-diameter vertical shafts of deep highway tunnels(700 m)in cold and highaltitude areas are hard to choose.Therefore,based on severe environmental requirements of Xinjiang,China,complex engineering geologies of the Tianshan,urgent need for ventilation in the"three-hole"combination of drilling and blasting method and TBM method,as well as various factors such as construction conditions,construction period,and cost control,a survey is conducted on various shaft excavation methods such as top-down boring method,raise-boring method,drilling method,and vertical tunneling machine method with different shaft depths in different industries globally.Then comprehensive comparison is conducted in terms of geological adaptability,construction period requirements,site conditions,technical maturity,safety,environmental protection,and cost.Based on the construction experience of the 2-2 vertical shaft project of the Tianshan Shengli tunnel,some conclusions are drawn as follows:(1)The top-down boring,raise-boring,and drilling methods are mature in coal mine projects,and corollary equipment is complete,whereas they are new in 700 m-deep vertical shafts with great difficulty.(2)Before construction of the shaft,the permeability coefficient, water inflow, rock lithology, strength, location and length of fracture zone should be investigated and rechecked in detail. (3) The drilling method will increase the cost and construction period when applying in hard rocks, which should be carefully selected. (4) The super-deep vertical shaft tunneling equipment and technology are still in the exploratory stage, the cost will be drastically increased due to long equipment manufacturing period, slurry pump replacement, deviation correction, grease leakage of cutterhead, and frequent cutter replacement.