内爆炸作用下隧道衬砌结构动力响应数值分析

为准确研究内爆炸作用下隧道衬砌结构的动力响应，建立了“炸药 空气 结构 土体”流固耦合模型对全比例隧道衬砌结构的内爆炸试验进行了数值模拟。模拟首先采用精细网格的一维轴对称模型计算起爆阶段爆炸波在自由场中的传播，并在爆炸波抵达衬砌结构前将一维轴对称模型计算结果映射至三维流固耦合模型中继续计算爆炸波、衬砌结构以及土体的相互作用。数值模拟获取的超压时程及衬砌结构破坏形态与试验结果吻合较好，说明了所建立数值模型以及映射模拟方法的适用性。基于数值仿真结果对于隧道衬砌内爆炸过程的爆炸波流场特征进行了分析。研究表明：偏心爆炸工况下冲击波在爆炸远区出现了较长时间的汇集，此区域的衬砌结构承受了较大的冲击波超压及冲量作用，为抗爆设计的薄弱部位。

Dynamic responses of tunnel lining structure under internal blasts

To investigate the dynamic responses of tunnel lining structure under internal blast loading accurately, an “explosive-air-structure-soil” coupled finite element (FE) model was established and verified by explosion test results of a full-scale tunnel lining structure. During the ignition phase, a On-dimensional (1D) axisymmetric model with fine mesh was adopted to calculate the propagation of the explosion wave in free space, and the result of the 1D model was mapped to the three-dimensional (3D) fluid-structure coupled model to calculate the interactions among explosion wave, lining structure and soil just before the explosion wave reached the lining structure. The calculated overpressure histories and failure modes of the lining structure fit well with experimental results, indicating the applicability of the FE model and the mapping technique. The characteristics of the explosion wave propagation in the lining structure were analyzed based on the FE model. The results indicate that under the eccentric explosion condition the explosion wave converges at the far-end for a long duration, and the lining structure at this zone, which undergoes large overpressure and impulse, should be regarded as the weak region in the anti-explosion design.