软土盾构隧道横断面变形规律及控制限值研究

Research on the Law and Controlled Limit Value of Transverse Deformation for Shield Tunnel in Soft Clay

研究目的:盾构隧道横断面变形对结构安全具有深刻的影响,变形过大会导致隧道接缝张开及渗漏、管片开裂,甚至导致横断面限界不足、隧道结构承载能力散失等,而盾构隧道修复加固代价高昂,为了确定合理的管片修复时机,在保证隧道安全性的同时兼顾经济性,需对隧道横断面变形规律及限值展开研究。研究结论:本文在隧道变形影响因素分析的基础上,得出如下结论:(1)横断面变形的根源在于隧道竖向和水平荷载比的增大;(2)以南京地铁二号线盾构隧道管片结构为背景,采用数值模拟的方法研究了隧道横断面变形规律,建立了不同拼装方式下隧道水平直径变形量与接缝最大张开量、最大螺栓应力、最大混凝土应力之间的关系,进而提出了隧道横断面变形控制限值:对于通缝隧道,水平直径变化量大于123 mm时螺栓达到极限强度值,对于错缝隧道,大于127 mm时螺栓达到极限强度值,此时隧道安全性将受到极大威胁;(3)本研究成果可为隧道横断面变形管控措施及修复时机的确定提供参考。

Research purposes： The transverse deformation of shield tunnel may deeply threaten the safety of tunnel structure. Excessive deformation may lead segment joints to open and leak and segments to craze. The deformation may even eause insufficient cross - section limit and the missing of structural - load - carrying capacity of the tunnel. On the other hand, it costs a lot to repair and reinforce the shield tunnel. In order to determine the proper moment to repair segments and ensure the safety of tunnel structure as well as economical efficiency, it is necessary to study the deformation law and limit value of the transverse section of the tunnel. Research conclusions： Based on the analysis of the influencing factors to causing the transverse deformation, the following conclusions was proposed： （ 1 ） The root of transverst deformation is increase of vertical and horizontal load ratio. （2）The shield tunnel properties of Nanjing Metro Line 2 was adapted to analyze the relationship between the variation of tunnel horizontal diameter andmaximum rate of joint opening, tress rate of both bolt and concrete using numerieal simulation, furthermore the controlled limit value of transverse deformationwas got, the bolt tress achieve maximal strength when the variation of tunnel horizontal diameter reach 123 mm for sequential segment seams,and 127 mm for staggeredsegment seams, which means severely threaten to the safety of shield tunnel. Finally the preeontrol and governance methodswere delivered to different influencing factors. （3）The research results can provide references to determine the controlling methods and restoration moment of the transverse deformation