冲击荷载下棚洞抗冲切性能研究

本文对落石冲击下棚洞钢筋混凝土顶板的破坏形式进行了研究,并按整体抗力相等的原则将板内配筋等效为薄钢板,在考虑垫层缓冲作用的基础上讨论了混凝土强度、棚洞顶板厚度以及顶板内所配钢筋的配筋间距、横纵向钢筋直径等因素对提高顶板抗冲切破坏性能的影响。结果表明:即使冲击速度不大,大质量的破坏性落石仍然会导致顶板贯穿块形成;板内配筋对贯穿块的阻力随着配筋间距的增大而减小,两者成反比例关系;横、纵向钢筋直径对配筋对贯穿块的阻力有显著影响,配筋阻力与横、纵向钢筋直径的平方之和成正比;垫层对落石冲击力的分散作用使得顶板上部的加载面积变大,这可以在一定程度上提高棚洞顶板的抗冲切承载力以及板内配筋对贯穿块的阻力;棚洞顶板的剪切破坏受多种因素控制,因此,在实际工程中应对棚洞所在区域的地质情况进行综合分析以对其进行设计。

Research on Punching Failure of Shed Under Impact Load

The failure modes of reinforced concrete roof of a shed tunnel under impact of rock-fall are studied and the reinforcement is equivalent to a thin steel plate according to the principle that the whole resistance is equal. The punching failure happened on the reinforced concrete roof of shed under the impact of rock-fall was studied. In the process of research the function of the buffer layer, the influence of concrete strength, thickness and configuration of shed tunnel roof are all being discussed to analysis their effects on the improvement of reinforced concrete. The results show that even the impact velocity is low, high quality destructive rock-falls can still lead to the formation of roof perforation block; The resistance of the reinforcement decreases with the increase of the reinforcement spacing and the relation between them is inverse; The diameters of transverse and longitudinal reinforcement have remarkable influences on the resistance of block, and the resistance of the reinforcement is proportional to the sum of the square of the transverse and longitudinal reinforcement diameter; The dispersion effect of cushion causes the loading area of roof being larger and this can improve the punching shear capacity and the resistance of plate reinforcement; The shear damage of shed tunnel roof is controlled by many factors, so the design has to be carried out on the comprehensive analysis of the geological conditions of the hole area.