管片钢筋和螺栓锈蚀条件下盾构隧道结构时变可靠度分析

Time-dependent Reliability Analysis of Shield Tunnel Structure under Corrosion Conditions of Segment Rebars and Bolts

针对管片钢筋与接头螺栓锈蚀对盾构隧道结构性态影响的不确定性,文章基于锈蚀实测数据,采用Gamma随机过程模型建立了材料锈蚀深度随时间增长的不确定关系。在ABAQUS软件中利用Python语言建立了隧道结构可靠度计算流程,分析了盾构隧道在不同钢筋和螺栓锈蚀状态下的结构可靠度,获得了隧道结构在极限承载力和正常使用两种极限状态下的失效概率随时间的变化规律。研究表明,在隧道全寿命周期内,一旦钢筋和螺栓发生锈蚀,在常见的20%~30%螺栓锈蚀率条件下,隧道结构失效概率即达到较高水平,30%以上的螺栓锈蚀率可使接头截面的承载能力失效概率接近100%。隧道结构一环衬砌的失效概率受螺栓锈蚀的影响较为显著,而钢筋锈蚀也会对管片的承载力及刚度产生较大影响。

As for the uncertainty of the influence of corrosion of segment rebars and joint bolts on the structural behaviors of shield tunnels,the uncertainty relationship between the material corrosion depth and the time is established by using a Gamma random process model on the basis of the measured corrosion data.In the ABAQUS software,the calculation process of tunnel structure reliability is established by using Python language to analyze the structural reliability of shield tunnels under different corrosion conditions of rebars and bolts,and the time-dependent variation laws of failure probability of tunnel structure are obtained under ultimate limit state and serviceability limit state.The study results show that once the rebars and bolts are rusted,the failure probability of the tunnel structure would reach a higher level under the common corrosion rate of 20%~30%in the whole life cycle of the tunnel,of which more than 30%bolt corrosion rate might make the failure probability of the bearing capacity on the joint section close to 100%.The failure probability of a lining ring of the tunnel structure is significantly affected by bolt corrosion,and rebar corrosion might also have a great impact on the bearing capacity and stiffness of segments.