不规则形状落石冲击棚洞动力响应与棚洞耗能缓冲机制

棚洞是我国西部艰险山区公路、铁路沿线防治落石灾害的主要措施之一。然而，由于缺少落石形状对棚洞动力响应影响机理的认识，基于现有认知和理论所设计出的棚洞，仍然存在被落石冲击破坏的现象。本项目聚焦三维形状这一影响落石冲击棚洞动力响应的重要因素，综合采用拍照式三维扫描技术、大尺度物理模型试验和离散元-有限元耦合数值模拟技术，开展不规则形状落石冲击棚洞动力作用的研究：构建一套基于球谐函数和颗粒填充法的不规则落石三维形状特征表征、量化和数值重构的方法；揭示落石冲击棚洞的宏细观动力过程、棚洞的耗能缓冲机制以及落石形状效应机制；建立落石冲击力、土垫层与棚洞顶板接触力与落石三维形状特征、质量和下落高度的定量关系。项目预期研究成果对揭示不规则形状落石冲击棚洞动力作用的内在力学机制有重要的科学意义，同时可为棚洞结构抗落石冲击设计提供技术支撑与科学依据。

Rock shed is one of the engineering measures commonly used to prevent rockfall along the highway and railway in western mountainous area of China. At present, due to the lack of understanding on the mechanism of the influence of rockfall shape on the dynamic response of rock shed, some rock sheds designed based on the current guideline can also been destroyed by the impact of rockfall. This study focuses on this key factor of three-dimensional rockfall shape. The 3D scanning technique, large-scale physical model test and combined discrete-finite element method are employed to investigate the dynamic response of irregular rock block impacting onto rock shed. Based on the spherical harmonic function and particle filling method, a set of methods for obtaining, quantifying, characterizing and numerical reconstruction of three-dimensional shape of irregular rockfall are established. The macro and micro dynamic process of rockfall impacting onto rock shed, the shape effect of rockfall and the energy dissipation mechanism of rock shed are revealed. The calculation methods of the impact force of rockfall and the contact force between soil cushion and roof slab of rock shed are established considering the shape, mass and falling height of rockfall. The expected results of this study have important scientific significance in revealing the mechanical mechanism of the dynamic response of rockfall impacting onto rock shed, and providing technical support and scientific basis for the design of rock shed.