碰撞作用下钢-混组合悬浮隧道管体局部响应分析

Local response analysis of steel-concrete composite submerged floating tunnel under collision

为了提高水下悬浮隧道(SFT)在外界碰撞作用下的安全性,其管体采用钢-混凝土组合截面。考虑材料非线性和应变率效应,采用ABAQUS有限元程序对钢筋混凝土截面、内衬式组合截面和外贴式组合截面管体在碰撞作用下的局部响应进行数值模拟;通过分析碰撞冲击力、混凝土损伤发展和耗能情况,对不同截面的防撞性能进行了对比,并分析了钢板厚度对内衬截面局部冲击响应的影响。结果表明,碰撞会造成悬浮隧道管壁内侧混凝土崩落和贯通损伤,威胁结构安全。外贴钢板会使冲击力峰值增大,加重管体混凝土损伤,对结构不利;内衬钢板在一定程度上能减小管体混凝土的损伤,且能有效防止碰撞时管壁内侧混凝土崩落,具有较好的密闭性和综合抗冲击性能;增大内衬钢板厚度能减小碰撞后管体的残余变形,但钢板厚度过大会导致混凝土管体开裂范围增大,设计时应综合管体变形和混凝土损伤情况,对内衬钢板厚度进行验算。

Here,to improve the safety of a submerged floating tunnel(SFT)under collision from outside,steel-concrete composite cross-section was proposed for its tube body.Considering material nonlinearity and strain rate effect,the finite element software ABAQUS was used to numerically simulate local responses of RC cross-section,inner lining type composite cross-section and outer sticking type composite cross-section,respectively under collision.Through analyzing collision impact force,concrete damage development and energy consumption,anti-collision performances of these three cross-sections were compared,and effects of steel plate thickness on local impact response of inner lining cross-section were analyzed.The results showed that collision can cause concrete collapse at the tunnel tube body wall inner side and penetrating damage of tunnel tube wall to threaten the structure safety;the outer sticking steel plate can increase peak value of impact force and aggravate tube body’s concrete damage to be unfavorable to tunnel structure;inner lining steel plate can reduce tube body concrete damage to a certain extent,and can effectively prevent concrete collapse on inner side of tube body under collision to have good tightness and comprehensive anti-impact performance;the tube body residual deformation can be reduced by increasing the inner lining steel plate thickness,but too large steel plate thickness can cause increase in cracking range of concrete tube,so this thickness should be checked by comprehensively considering deformation of tunnel tube body and concrete damage when designing SFT.