岩体隧道衬砌长期承载力时变可靠度分析方法初探

Discussion of Time-Dependent Reliability Analysis for Long-Term Bearing Capacity of Rock Tunnel Linings

针对岩体隧道衬砌长期承载力可靠度分析,文章分别以初始时刻及现时刻为分析时间起点,建立了考虑抗力随时间变化的使用期内隧道衬砌承载力可靠性分析模型。在此基础上,以某海底公路岩体隧道为例,对海域Ⅲ级（Ⅳ类）围岩下衬砌在不同使用期内的长期承载力可靠度进行评估,计算结果表明：（1）随着运营时间增加,岩体隧道计算断面衬砌的长期承载力可靠度指标不断减小;（2）该隧道计算断面衬砌拱腰处的承载力可靠度指标最大,最大弯矩处的承载力可靠度指标最小,即计算断面衬砌在弯矩最大处最不安全;（3）隧道运营60a时计算断面最大弯矩处衬砌的有效概率大于99%,60a之后至其有效期（100a）,有效概率在95%-99%之间。在设计使用期内,该隧道计算断面拱顶、拱腰和最大弯矩处衬砌的有效概率均大于99%。

In order to examine the long-term bearing capacity of rock tunnel linings, a reliability analysis model for the bearing capacity of a tunnel lining over its lifecycle was established with consideration of time-dependent re-sistances by taking the initial time and present time as the start times, respectively. On this basis, using a subseahighway rock tunnel located in grade Ⅲ（classification Ⅳ） surrounding rocks under the sea as an example, the long-term bearing capacity reliability of a tunnel lining under different lifetimes was assessed. The results show that： 1）the long-term bearing capacity reliability index of the calculated section of the tunnel lining decreases with an in-crease of operation time; 2） the long-term bearing capacity reliability index at the haunch of the calculated sectionis the highest and it is the lowest at the maximum bending moment point, which is to say that the lining at the maxi-mum bending moment point is the least safe; 3） within an operation time of 60 years, the effective probability of thetunnel lining at the maximum bending moment point is more than 99%, and it is between 95% and 99% for the timeperiod after 60 years to the tunnel design life limit（100 years）, with the effective probabilities of the tunnel lining atthe crown, haunch, and maximum bending moment point being more than 99% during the tunnel′s design lifetime.