水下非接触爆炸冲击作用下悬浮隧道动力响应

Dynamic Response of a Submerged Floating Tunnel During Non-contact Underwater Explosions

为了研究水中悬浮隧道在近场非接触爆炸荷载作用下的运动学及动力学行为规律,通过任意拉格朗日欧拉耦合算法处理流固耦合和强间断流场模拟问题,采用Jones-Wilkins-Lee(JWL)方程和Mie-Gruenisen状态方程分别模拟爆生气体和水的压力,并利用基于势流理论和边界元法的LSDYNA有限元动力学程序实现上述问题求解计算,分析锚索支撑体系、炸药量和爆心距离对悬浮隧道结构位移、速度、加速度和应力的影响。结果表明:非接触爆炸冲击作用下,3种支撑体系的差异对悬浮隧道管段的位移、速度、加速度和应力影响较小,相同爆炸荷载作用下垂直支撑锚索的轴力远小于其他2种工况(组合支撑和倾斜支撑),组合支撑体系和倾斜支撑体系比垂直支撑体系锚索轴力最大值要大296%和283%;管体的位移、速度和应力随着炸药量增加近似呈线性增加,加速度近似呈抛物线增加,200,500kg炸药引起的管段跨中加速度比100kg炸药引起的加速度大26.2%和223%,炸药量是影响悬浮隧道结构安全性的关键因素;管段位移、速度、加速度和应力随着爆心距增加而近似呈幂函数下降;与2m爆心距相比,5,10,20m工况时加速度峰值分别下降了73.2%、94.2%、97.5%;通过回归分析和拟合函数可计算满足结构安全的允许炸药量和安全距离,进而为非接触爆炸荷载作用下悬浮隧道的安全性评价提供依据。

To study the regularity of the kinematics and dynamics of a submerged floating tunnel（SFT）subjected to near-field non-contact underwater explosions,fluid-solid coupling was employed and the problem of how to simulate a flow field with strong discontinuities was considered using the Arbitrary Lagrange Euler（ALE）coupling method.Explosive gas and water pressures were simulated using the Jones-Wilkins-Lee（JWL）and Mie-Gruenisen equations,respectively.To calculate the aforementioned problems,the LS-DYNA finite element kinetics program based on the potential flow theory and boundary element method was adopted.This study investigated the effects of three support systems（vertical,inclined,and combine the two cases）as well as the explosive quality and distance to the explosion center based on the displacement,velocity,acceleration,and stress of the SFT.The results indicated that afteranon-contact explosion,the three support systems had a slightly different effects on the displacement,velocity,acceleration,and stress of the SFT.The cable axial force of the vertical support system was considerably less than that of the other two cases under the same explosive load.Compared with that of the vertical support system,the maximum cable axial force of the combined and inclined support systems was 296% and 283% higher,respectively. The displacement,velocity,and stress of the SFT increased linearly with increased explosive quality,and the acceleration was approximated by aparabolic increase.The accelerations of the SFT at midspan caused by the 200 kg and 500 kg explosives were 26.2% and 223% greater,respectively,than the acceleration caused by the 100 kg explosives.The explosive quality was a key factor that affected the security and stability of the SFT structure.The displacement,velocity,acceleration,and stress of the SFT experienced a reduction in power function with the increase in distance to the explosion center.In terms of acceleration,compared with the 2 m distance to the explosion center,the acceleration peaks were reduced by 73.2%,94.2%,and97.5% under the 5 m,10 m,and 20 m operating conditions,respectively.In addition,the allowable explosive quality and safety distance were calculated by regression analysis and by using a fitting function,which provided a basis for a security evaluation of the SFT under a non-contact underwater explosion load.