落石冲击作用下棚洞-拦石墙顶板及缓冲层的动力响应

Dynamic Response of Ceiling and Buffer Layer of Shed Tunnel and Rock Barrier Wall Under Rockfall Impact

以黔张常铁路(黔江—张家界—常德)为例,采用离散元软件PFC3D与有限差分软件FLAC 3D进行耦合计算,研究落石冲击棚洞-拦石墙顶板及缓冲层的动力响应,优化棚洞-拦石墙顶板及缓冲层设计,并对掺有轮胎颗粒的缓冲层进行研究。结果表明:可适当减小棚顶厚度,达到减轻结构自重与节省原料的目的,但棚顶厚度不宜小于0.4 m;适当增加缓冲层厚度可以减小落石冲击力,从而减小顶板挠度与应力,且缓冲层厚度不宜低于0.50 m;缓冲层添加20%~30%轮胎颗粒能有效提升缓冲层防护效果。

Taking the Qianjiang-Zhangjiajie-Changde railway as an example,the discrete element software PFC3D and the finite difference software FLAC 3D were used to conduct coupling calculations to study the dynamic response of the ceiling and buffer layer of the shed tunnel-rock barrier wall under rockfall impact,optimize the design for the ceiling and buffer layer of the shed tunnel-rock barrier wall,and study the buffer layer mixed with tire particles.The results show that the thickness of the ceiling can be appropriately reduced to reduce the dead weight of the structure and save raw materials.However,the thickness of the ceiling should not be less than 0.4 m.Increasing the thickness of the buffer layer appropriately can reduce the impact force of falling rocks,thereby reducing the deflection and stress of the ceiling,and the thickness of the buffer layer should not be less than 0.50 m.Adding 20%~30%tire particles to the buffer layer can effectively enhance the protective effect of the buffer layer.