在役隧道结构多失效模式时变可靠性研究

隧道衬砌结构服役寿命期内的可靠性研究对隧道安全管理具有重要意义。对于混凝土衬砌而言,在服役过程中受到多种时变因素的共同作用,结构存在多种失效模式。为此,提出基于抗力衰减控制、最大裂缝宽度控制和混凝土碳化深度控制的多失效模式的服役隧道衬砌结构时变可靠度分析方法,采用概率故障树模型构建衬砌多失效模式系统可靠度分析模型,利用JC法计算结构的可靠度指标和失效概率,分析衬砌结构可靠度服役期内的变化规律和不同失效模式对可靠性的影响。将该方法进一步应用于某一病害隧道的可靠度分析中,结果表明:随着服役时间的不断增长,结构的可靠度指标不断降低,且多失效模式下的结构失效概率高于单一失效模式。拱顶处相比于其他位置失效概率较高,抗力衰减失效模式对结构可靠性影响最大。模型可以较为合理地反映结构的可靠度水平及变化规律,为衬砌结构可靠性评价提供一种科学合理的参考方法。

Study on Time-dependent Reliability of In-service Tunnel Structure under Multiple Failure Modes

The reliability study of tunnel lining structure during service life is of great significance to tunnel safety management. The structure of the concrete lining is subject to multiple failure modes in due to a variety of time-varying factors in the service process. For this reason, a time-dependent reliability analysis method for service tunnel lining structure is proposed based on multi-failure mode of resistance attenuation control, maximum crack width control and concrete carbonation depth control. Probabilistic fault tree model is used to construct the lining multi-failure mode system reliability analysis model. The JC method is employed to calculate the reliability index and failure probability of the structure, and the variation law of the reliability of the lining structure during service and the impact of different failure modes on the reliability are analyzed. The method is further applied to the reliability analysis of a defected tunnel. The results show that as the service time increases, the reliability index of the structure decreases continuously, and the structural failure probability in multiple failure modes is higher than that in single failure mode. The failure probability of the dome is higher than that of other locations, and the resistance decay failure mode has the greatest impact on the structural reliability. The model can reasonably reflect the reliability level and variation law of the reaction structure, and provides a scientific and reasonable reference method for the reliability evaluation of the lining structure.