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

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. © 2021, Editorial Office of Journal of Vibration and Shock. All right reserved.