管片衬砌隧道内爆炸问题研究

Most subway（highway）tunnel lining structures are assembled with segments,which are connected with curved bolts. The deformation characteristic of assembled multisegment lining is different to that of the one-piece casting. So far there are an abundance of research achievements about the subway tunnel lining structure's deformation and movement under ordinary operation situations (under the static and vibration loading) for reference, while the research of that under explosion loading come into existence recently, and many theoretical mechanisms research are absent. As the attack risks of the underground traffic tunnels are increasing, to carry out anti-terrorist bombings research and evaluation work of traffic tunnels has very important theoretical and practical significance. The research on the basis of previous theoretical and experimental work should be carried out in four aspects: 1. The regulation of shock wave overpressure in the tunnel for offcenter explosion;2. The dynamic stiffness and strength of tension, shear and torsion in contiguous area of multisegment lining under different loading rate; 3. The dynamic interaction between the surrounding soil, joints and segments under initial soil pressure and internal explosion loading; 4. The practical calculation procedure on deformation and destruction of the multisegment lining structure.This research is mainly aimed at providing technical support for estimation of the anti-internal explosion design and explosion-resistant capacity.

许多地铁（公路）隧道衬砌结构由管片拼装而成，接头部位采用螺栓连接。在荷载作用下，管片衬砌结构的变形特征与整体浇注衬砌结构有很大区别。正常运营时（包括静荷载和振动荷载作用）管片衬砌结构的变形和运动规律性有很多的研究成果可以参考应用，而隧道内爆炸荷载作用下变形和破坏规律性的研究还刚刚起步，许多机理性的研究还是空白。由于针对地铁隧道的爆炸威胁愈来愈严重，因此展开管片类衬砌结构内爆炸问题的研究具有重要的理论与现实意义。项目在前期理论和试验研究成果的基础上主要进行四个方面的工作：①偏心爆炸条件下管道内部冲击波超压的时空变化规律；②不同加载速率条件下管片衬砌结构接头部位拉伸、剪切和扭转的动力刚度和强度确定；③土压力和内爆炸荷载共同作用下土、接头区域和管片的动力相互作用问题；④考虑内爆炸荷载作用时管片衬砌结构变形和破坏问题的实用计算方法。目标是为管片类衬砌结构抗内爆炸设计和抗爆性能评估提供参考。

项目采用试验研究、理论研究和数值模拟相结合的方法，对管片衬砌隧道内爆炸问题进行了研究，主要研究成果如下：.1. 完成了竖向拼装条件下的错缝全比例管片衬砌结构模型内爆炸的试验，得到了内爆炸荷载的基本特征和管片衬砌结构响应规律。偏心内爆炸荷载流场复杂，爆心环面远端的初始反射超压较低，但由于反射波的叠加、汇聚其比冲量较之自由场单次反射增强了40倍以上。管片衬砌变形主要是径向膨胀造成的管环环向受拉，接头螺栓部位存在明显的应变集中和破坏现象。.2. 建立了管片衬砌结构的运动学模型。该模型运动学方程中包含了初始地应力状态的影响。计算表明，振动周期接近试验中所测得的结构环向应变曲线波形的时间特征。.3.对厚壁管片衬砌结构在均布内爆炸荷载作用下的弹塑性响应进行了计算分析，并对埋深、爆炸荷载正压时间与结构自振周期之比、内爆炸荷载冲量的增强效应等参数对结构响应的影响进行了评估；.4. 阐述了管片衬砌结构的极限状态分析方法，推导了弹性土中单自由度刚塑性结构模型的位移响应的解析解，并初步阐述了结构等损伤曲线的求解方法；.5. 对管片接头处局部区域在爆炸荷载作用下的变形规律性进行了数值分析，阐述了结构的动力变形机理和破坏规律，提出了简单的减爆措施；.6.对不同当量和不同偏心量的内爆炸过程进行数值模拟，总结出内爆炸情况下圆形隧道结构内壁反射超压的变化规律，通过引入等效脉冲概念，拟合推导出了可用于简化计算的考虑多次反射的内壁超压计算方法。.项目实施对研究管片衬砌结构内爆炸荷载环境、抗爆性能评估以及抗爆减爆措施制定具有重要的参考价值。