组合式棚洞结构优化及其计算方法

棚洞是山区公路常见的崩塌落石灾害防治结构。本文通过增设夹心层和增设薄壁管二次消能装置对组合式棚洞结构进行了优化。通过对夹层结构等效并采用薄板理论,建立了棚洞优化结构的内力计算式。利用圆柱壳冲击动力学分析二次消能特性,将组合式棚洞优化结构在落石冲击作用下的动力响应分为四个阶段,建立了三个临界冲击速度的计算式。实例分析表明,棚洞优化结构横梁和纵梁的上、下侧最大弯矩比优化前分别降低了19.7%, 23.7%和10.2%。第一、第二、第三界限冲击速度分别为6.24 m/s、13.50 m/s、15.20 m/s。研究成果对组合式棚洞优化结构的构件预制有指导意义。

Structure optimization and calculation method of combined shed-tunnel structure

Shed-tunnel is one of common structures for prevention and control collapse and falling rocks along highway in mountainous areas.In this paper,optimization of combined shed-tunnel structure was optimized by adding sandwich layer and secondary energy dissipation device made of thin-walled tubes.The internal force calculation formulas for the optimized structure of shed-tunnel were established by using equivalent method of sandwich structure and the thin plate theory.Through analysis of the secondary energy dissipation characteristics by cylinder dynamics,response of the optimized structure under impact of rockfalls was divided into four stages,and formulas to calculate the three critical impact velocity were established.Case analysis shows that the maximum bending moments of the cross beam,the upper and lower sides of the longitudinal beam for the optimized structure are reduced by 19.7%,23.7%and 10.2%respectively before optimization.Further,the first,second and third critical impact velocities are 6.24 m/s,13.5 m/s and 15.2 m/s,respectively.The reseach results have guiding significance for prefabrication of the components of the combined shed-tunnel’optimized structure.