基于摄动理论盾构隧道壁后脱空识别分析研究

隧道工程中的壁后脱空病害具有极强的隐蔽性和不确定性,针对盾构隧道中脱空损伤问题,研究了盾构隧道在脱空损伤下其动态特征的变化规律。采用摄动理论分析,建立表征脱空损伤系数η,并结合δ函数的性质,推导了脱空损伤下盾构隧道的模态特征解析式,并引入模态应变能损伤指数进行损伤定位。最后以上海地铁某盾构隧道为例,对无脱空损伤、脱空损伤条件下进行摄动理论分析及有限元分析,结果表明:无论采用摄动理论分析还是有限元分析都能较好地对脱空损伤进行动态演化分析,同时模态应变能损伤指数也能够较好地对脱空位置进行定位,可为基于动力特性的隧道脱空损伤识别和动态监测提供理论依据。

Research on the Dynamic Evolution Analysis of the Cavity Damages of Shield Tunnel Based on Perturbation Theory

Cavity defects in tunnel engineering have the characteristics of damage hidden and uncertainty.Aiming at cavity defect after tunnel wall,the dynamic characteristics of tunnel structure are put forward to illustrate the changing rules.Based on the perturbation theory analysis,coefficient ηrepresents the level of cavity defect was established,combined with the function δ,the modal behaviors of the analytical formula of shield tunnel structure were derived.The modal strain energy damage indicator was introduced to identify the cavity location.Finally,a metro tunnel in Shanghai city was taken as an example,the dynamic evolution analysis was carried out based on perturbation theory analysis and finite element analysis.The results show the modal strain energy damage indicator demonstrates that the introduced lining degradation can be successfully detected and located.The results can be used to provide theoretical basis for the dynamic monitoring of shield tunnel structure.