水下爆炸-移动作用下悬浮隧道管体响应

Response of submerged floating tunnel under action of underwater explosion-moving load

为了研究水下爆炸-移动作用下悬浮隧道管体的变形规律,基于Cole冲击波半经验公式和Vernon气泡运动方程将水下爆炸过程简化为冲击波和气泡脉动作用两个阶段,将公路I级荷载简化为移动荷载序列,通过D′Alembert原理建立了一个考虑水下爆炸荷载、移动荷载以及流体作用的悬浮隧道动力学模型,采用四阶Rungek-Kutta法求解运动微分方程组,利用已有的数据和公式对模型进行验证,最终讨论爆炸荷载、移动荷载对隧道管体变形的影响。结果表明:冲击因子?能够极大促进悬浮隧道最大位移的增加;在仅爆炸荷载作用下与?=0.1相比,冲击因子增大2倍和4倍,隧道最大位移分别增大了4倍和10倍;气泡荷载频率随炸药量的增大成指数增大,随爆点水深的增大气泡荷载频率成反比例下降;不同炸药量和水深情况下,气泡荷载频率均小于3 Hz,与隧道低阶频率相近容易导致共振。在水下爆炸和移动荷载作用下,悬浮隧道的最大位移受到移动荷载位置和速度的综合影响,其中车辆以最快速度行驶至跨中时发生爆炸危害性较大。

To investigate the deformation law of submerged floating tunnel(SFT) subjected to underwater explosion-moving load, the underwater explosion process was simplified to the stages of shock wave load and bubble motion based on the Cole shock wave load semi-empirical formula and Vernon bubble motion equation. The Grade I vehicle load of highway was simplified to the moving load sequence. A dynamic model of SFT considering underwater explosive load, moving load, and fluid effect was established based on the D’Alembert’s principle. The four order Runge-Kutta method was adopted to solve the differential equations of motions, and the proposed model was verified by using the existing data and formulas. Finally, the effects of explosive load and moving load on the deformation of the tunnel were discussed. Results show that the impact factor ? could greatly promote the increase in the maximum displacement of SFT. Compared with ?=0.1, when the impact factor increased by 2 times and 4 times, the maximum displacement of the tunnel increased by 4 times and 10 times under explosive load alone. With the increase in the explosive amount, the bubble load frequency increased exponentially, with the increase in the water depth of the explosion point, the bubble load frequency decreased in inverse proportion. In the cases of different explosive amounts and water depths, the bubble load frequencies were all less than 3 Hz, which was close to the low-order frequency of the tunnel and easily led to resonance. Under the action of underwater explosion and moving load, the maximum displacement of SFT was affected by the combined effect of the position and speed of the moving load, and the explosion was more harmful to the tunnel when the vehicle ran at the fastest speed until the mid-span.