瓦斯剧烈爆炸隧道衬砌损伤数值模拟与机理分析

Numerical simulation and mechanism analysis of tunnel lining structure damage subjected to severe gas explosion

洛带古镇隧道瓦斯爆炸致灾为近年来唯一、典型的公路隧道内剧烈爆炸案例,为探究隧道衬砌在剧烈爆炸效应下的损伤机理,对爆源进行等效、量化研究,采用RHT模型模拟衬砌并修正部分关键参数,在LS-DYNA中使用ALE技术建立与隧道横断面尺寸一致的流固耦合数值模型,模拟了隧道衬砌的损伤过程并分析其受力状态。研究表明:爆心距0~5.1 m范围的衬砌在爆炸冲击波剧烈冲压作用下由局部破坏发展为完全破坏;爆心距5.1~10.9 m范围衬砌上密集的损伤裂缝在拉、压交替作用下扩张将衬砌分割成块状结构形成严重破坏区;爆心距10.9 m以外衬砌主要在拉应力下产生纵向、环向损伤裂缝,为一般损伤区;衬砌受损部位主要位于拱部、曲边墙处,曲边墙脚处的"犄角结构"使得该处破坏尤为严重。数值模拟结果与隧道实际损伤调查情况及基于SDOF法对隧道损伤评价结果基本一致,表明研究方法合理、计算参数取值可靠,可为大型复杂结构体内爆炸或可燃气体爆炸问题研究提供参考。

The gas explosion accident in Luodaiguzhen tunnel is the only one typical severe inner-blast case in the highway tunnels in recent years,in order to investigate the damage mechanism of tunnel lining under severe explosion effect,the equivalent and quantization of the burst source is studied,the RHT model is used to simulate the lining structure and correct some key parameters,using ALE technique in LS-DYNA to establish a fluid-structure coupled numerical model with uniform size of tunnel cross-section,the damage process of tunnel lining is obtained and its stress state is analyzed.The study show that： Within 5.1 meters of detonation the lining is developed from local destruction zone into completely destructive zone under the action of explosive shock wave dramatically stamping action; Within 5.1-10.9 meters of detonation massive damage cracks on the lining expands cut the lining structure into blocky structures form a severely damaged zone under the alternating action of tensile and compressive force; Distance from detonation beyond 10. 9 m the longitudinal and circumferential damage cracks in the lining are mainly caused by tensile stress,which is the general damage zone; The damaged part of the lining is mainly located in the arch and curved sidewalls,and the ＂ Horn structure＂ in the corner of the curved side walls makes the damage particularly serious.The numerical results are basically consistent with the actual damage investigation of Luodaituzhen highway tunnel and the damage evaluation that based on SDOF approach,which indicates that the research give a reasonable method and reliable calculation parameters,and provide reference for the study of the large complex structure inner explosion or combustible gas explosion.