关于隧道结构的安全推演及寿命预测

Safety Deduction and Life Prediction of Tunnel Structure

隧道的寿命一直是行业研究的重要课题,相关研究大致可分为两类:一类是基于隧道环境的材料耐久性研究,认为衬砌寿命即隧道寿命;另一类是基于材料劣化的结构安全性研究,不考虑隧道结构受力对材料劣化的影响。现结合上述两类研究提出隧道结构体系受力演变模型,以反映各种因素的相互作用及隧道结构的内力演变和安全性演变,是一种新的研究思路。研究的主要内容有两项:其一为钢筋混凝土偏压构件的安全性演变;其二为隧道衬砌结构的内力及安全性演变。前者基于目前钢筋混凝土材料耐久性的研究成果,分析了材料劣化过程对偏压构件安全性演变的影响规律;后者通过隧道结构体系受力演变模型,分析了材料劣化及病害发展过程等对隧道结构内力和安全性演变的影响规律。研究表明:钢筋混凝土材料具有良好的耐久性,正常情况下能满足隧道设计寿命的要求,结构安全受钢筋锈蚀的影响比混凝土劣化要大很多,延缓钢筋锈蚀是隧道预防性养护的工作重点之一;隧道衬砌裂缝的出现会改变结构的内力分布,但一般不至于引起结构内力的明显恶化,除非裂缝存在发展迹象;拱脚处地层弱化对隧道结构安全的危害较大,维持围岩的稳定以及衬砌背后的密实性,是保障隧道结构安全性和使用寿命的前提条件。

The service life of tunnel has always been an important subject of industry research,the related researches can be divided into 2 categories.One is the tunnel environment based durability research of material which considers life of lining as life of tunnel.The other is the material degradation based safety research of structure which does not consider the influence of tunnel structure stress on material degradation.In order to reflect the interaction of various factors and the evolution of internal force and safety of tunnel structure,the force evolution model of tunnel structure system is proposed based on the 2 categories of researches,which is a new research idea.Two main contents are contained in the research.One is the safety evolution of reinforced concrete structures under biased compression.The other is the internal force and safety evolution of tunnel lining structure.The former is based on the researches of durability of reinforced concrete materials,the influence of material deterioration on the safety evolution of eccentrically loaded members is analyzed.For the latter,the influence of material deterioration and disease development on the internal force and safety evolution of tunnel structure is analyzed through stress evolution model of tunnel structure system.It shows that(1)Reinforced concrete materials have good durability and can meet the requirements of the design life of the tunnel under normal circumstances.Structural safety is much more affected by the corrosion of steel bars than by the deterioration of concrete,and delaying the corrosion of steel bars is one of the=key points of tunnel preventive maintenance.(2)The appearance of tunnel lining cracks will change the distribution of structural internal force,but generally it will not cause the obvious deterioration of the structural internal force,unless there are signs of development of the crack.(3)Weakening stratum at arch foot does great harm to tunnel structure safety.Maintaining the stability of surrounding rock and compactness behind lining are the precondition to guarantee the safety and service life of tunnel structure.