行波效应下预制综合管廊组合式纵向接头破坏模式和抗震性能研究

As a key priority of municipal infrastructure construction in China in the future, the seismic safety of underground utility tunnels is very important. But there are still several deficiencies in the current studies on the longitudinal earthquake-resistance problems of utility tunnel: the active mechanism of travelling wave effect is still under investigation; the failure modes of longitudinal joint are still not clear; and the appropriate seismic performance indices and standards are still lacking. This project will focus on the combined longitudinal joint's earthquake-resistance problems of precast utility tunnel. Firstly the mechanical properties of utility tunnel joint under compound bending-shear-torsion load will be revealed according to low-frequency cyclic loading tests and refined numerical simulations. After that, the whole three-dimensional finite element model for soil-tunnel-joint unity will be established, and travelling wave effect will be implemented by the obliquely incident seismic waves along the longitudinal direction. And the failure modes of utility tunnel joint will be discovered due to dynamic numerical computation. Then an appropriate seismic damage index and the failure classification standard for utility tunnel joint will be proposed based on the mechanical properties and failure modes. After the logistic regression analyses on the results of IDA, an appropriate earthquake intensity index will be selected on account of correlation coefficients. Finally the seismic performance evaluation for combined longitudinal joint of precast utility tunnel will be completed.

地下综合管廊作为未来我国市政基础设施建设的重点，其地震安全性十分重要。但目前对综合管廊纵向抗震问题的研究还存在诸多不足，对行波效应的作用机制尚不明了，对纵向接头的破坏模式还不清楚，更是缺乏合理的抗震性能指标和抗震设防标准。本项目针对预制地下综合管廊组合式纵向接头的抗震问题开展研究工作。首先通过低周往复加载试验和接头精细化数值模拟揭示管廊接头在弯-剪-扭耦合作用下的力学行为。然后在此基础上建立土体-管廊-接头的整体三维有限元模型，在边界输入沿纵向斜入射的地震波以模拟行波效应，通过动力数值计算探明管廊接头在行波效应下的破坏模式。再根据其力学性能和破坏模式提出适用于管廊接头的地震损伤指标和破坏等级划分标准，并对增量动力分析的结果进行对数回归分析，根据相关性系数选择合理的地震强度指标，最后完成对预制综合管廊组合式纵向接头的抗震性能评估。

地下综合管廊作为生命线工程的重要组成部分，其地震安全性非常关键，而行波效应造成的纵向变形，是综合管廊产生破坏的重要原因。目前对综合管廊的纵向抗震研究还存在不足，对管廊接头的力学行为尚不明了，也缺乏高效的综合管廊弹塑性纵向抗震分析方法。本项目针对预制地下综合管廊组合式纵向接头的抗震问题开展研究工作。首先通过精细化数值模拟揭示管廊接头在低周往复加载下的力学行为，并对其刚度退化和滞回耗能等特征进行了分析。然后提出了合理的管廊接头本构和地基弹簧本构，并结合地震波斜入射条件下水平成层场地地震响应分析，在建立了一套高效的地下综合管廊弹塑性抗震分析方法。最后选取合理的地震强度指标与地震需求指标，通过对增量动力分析的结果进行对数回归分析，建立了管廊接头的地震需求模型，实现了对其抗震性能的评估。