公路隧道欠厚二次衬砌的统计特征及其安全分析

二次衬砌是公路隧道主体结构的最后一道安全屏障,针对其欠厚缺陷开展相关研究具有重要现实意义。本文首先通过大量资料的统计,分析了公路隧道二次衬砌欠厚的程度、空间分布和地质分布等形态参数特征;继而在此基础上,确定了数值计算模型;然后,运用数值模拟方法,对欠厚二次衬砌在不同缺陷部位和程度等参数下的安全性进行了分析。结果表明:公路隧道欠厚二次衬砌的形态特征复杂多变,总体上欠厚部位主要分布于拱部和Ⅳ级围岩,洞口段最为密集,且欠厚程度超过33.3%的部位不足10%;隧道欠厚衬砌的安全系数与欠厚程度呈正相关降低,且安全系数对欠厚厚度的敏感程度较欠厚宽度大,其空间安全性也与欠厚位置紧密相关;边墙隅角处和拱顶是欠厚衬砌的安全控制部位。

Analysis of Statistical Characteristics and Safety of the Secondary Lining with Thickness Lack for Road Tunnel

The secondary lining is the last safety barrier of the main structure of the highway tunnel,and it has important practical significance to research the thickness lack defect of the lining.Firstly,through a large number of data statistics,some morphological parameters characteristics were analyzed,including thickness lack degree,spatial distribution and geological condition for the lining;then,the numerical calculation model was set up;finally,the safety of the secondary lining with thickness lack under different defection location and degree conditions was analyzed by numerical simulations.The results show:the morphological parameters characteristics of the secondary lining with thickness lack are complex.Generally these linings mainly distributed in the arch sections and the Ⅳ level surrounding rock sections,and those most intensive are in the portal sections.Those positions whose thickness lacking degree exceeding 33.3％ are less than 10％;The safety factor of the secondary lining with thickness lack is positively decreased by the thickness lack degree,and the safety factor is more sensitive to the thickness than the width;The space security is closely related with the thickness lack position;The side wall comer and the vault are the controlling part of the secondary lining with thickness lack for safety.