城市地铁隧道击穿安全影响分析及其应对措施

Analysis of Breakdown Safety Influence of Urban Subway Tunnel and Its Countermeasures

研究目的:近年来,各地轨道交通隧道受外部作业影响导致被击穿的情况越来越多,对轨道交通安全运营造成严重威胁,虽然各类隧道被击穿情况不尽相同,但在隧道衬砌安全影响分析与结构补强处理等方面存在很多相同之处,需尽快明确各类修补措施的优缺点并提出改进方案,建立标准化处理措施,确保既有线安全运营。研究结论:(1)将隧道上半断面碎裂情况按区分类,拱顶左右30°范围为内侧受拉区域(Ⅰ区),拱腰以上40°范围为内侧受压区域(Ⅲ区),隧道中心线两侧30°~50°范围为内侧拉压转换区域(Ⅱ区);(2)小范围破损时,隧道短期内可基本维持稳定,但会逐渐引起隧道上方地层荷载模式的转变,可能导致隧道拱顶区域内力值急剧增加、管片裂缝宽度显著增大,宜尽快对破损位置进行修补;(3)明确了常用洞内外修补措施的优缺点与结构加固原则:小范围碎裂应以洞内修补为主,给出了洞内钢板粘贴加固方法及其关键技术;大范围碎裂可考虑基于竖井(或基坑)的洞外修补方法,提出了基于上尖下圆拱形转换构件的竖井方案,将竖井内回填土竖向荷载最大程度转化为水平向荷载;(4)竖井洞外修补方案,管片破碎至竖井开挖阶段,拱顶弯矩增大、轴力减小,影响结构安全;管片破碎修复部位,在回填土荷载作用下,内力(弯矩)可能出现翻转,由内侧受拉转变为外侧受拉,可能会加剧管片内侧裂缝或局部碎裂现象;(5)本研究成果可用于各类隧道结构的修补或加固处理。

Research purposes: Nowadays, tunnels broken down by outer activities are more and more common in urban areas during construction and operation phase. Safety operation and surroundings will be seriously affected correspondingly. The lining broken circumstances are different. However, there are many similarities in tunnel safety analysis and structure reinforcement. The lining repair methods and its relevant improvements should be made clear as soon as possible, and the standardized lining repair methods should be established as soon as possible to meet the safety operation requirements of rail transit.Research conclusions:(1) Three typical lining fragmentation modes are put forward. The inner tension area is within 30° on both sides of tunnel vault, namely section Ⅰ. The inner compression area is within 40° above arch waist, namely section Ⅲ. The tension and compression conversion area is in the range of 30°~50° on both sides of the tunnel vault, namely section Ⅱ.(2) Tunnel safety can be basically ensured due to little range of lining fragmentation, but continuous influences on earth load mode change will be resulted, and significant increase of lining stress and crack width may be induced correspondingly, so it is advisable to repair the damaged position as soon as possible.(3) Advantages and disadvantages of common lining repairing measures, and the corresponding lining reinforcement principle are put forward. The reinforcement of little range of fragmentation should be carried out in tunnel, and the construction method and key technologies for steel plate reinforcement is made clear. The reinforcement method based on shaft or pit foundation is put forward for large range of fragmentation. The up-peaked and down-round arch-transit structure is put forward in shaft method, and the vertical load of backfill soil can be transferred into horizontal load.(4) As for shaft repair method, segment moment will increase and axial force will decrease from segment broken stage to shaft excavation stage, and lining safety will be influenced. The lining bending moment may turn over in fragmentation position after soil backfilling process. The inner tension will change to lateral tension, and the fracture and fragmentation will be aggravated.(5) The research results can be used for all kinds of tunnel remediation.