三开间单跨柔性棚洞在落石冲击作用下的试验研究

为克服钢筋混凝土结构式棚洞施工难度大，费用高等不足，满足快速抢修抢建要求，提出一种由型钢拱架和金属网组成的柔性棚洞。由于三开间单跨柔性棚洞的传载耗能特点与单开间单跨柔性棚洞存在区别，为此在现有单开间单跨柔性棚洞研究的基础上，提出三开间单跨柔性棚洞的设计方案，制作1∶1试验模型，并进行了25kJ、50kJ、100kJ和250kJ的落石冲击试验。宏观试验现象表明：①当落石能量在100kJ范围内时，柔性棚洞能够成功的对其进行拦截，而不需要对结构进行维护；②当落石能量在250kJ时，柔性棚洞在成功对其进行拦截的情况下，仅需要经过简单的维护即可继续投入使用；③柔性棚洞内的净空满足安全要求。此外，采用应变片、荷载传感器和高速摄像机等对落石冲击过程和柔性棚洞中钢拱架的动力反应进行了测试，综合试验测试数据，对柔性棚洞的变形特点、传载耗能机理和破坏特点进行了分析，指出了柔性棚洞中易发生破坏的薄弱部位，提出了下一步柔性棚洞的改进措施。

Experimental investigation on three-bay and single-span flexible rock-shed under impact of rockfall

In order to overcome construction difficulty, reduce costs of conventional concrete rock-shed, and satisfy the emergency construction and maintenance, a new type of flexible rock-shed made of flexible nets held up by specially designed steel vaulted structure was proposed. Due to the differences of the load transfer and the energy dissipation mechanism between the single-bay and single-span flexible rock-shed and three-bay and single-span flexible rock-shed, the design scheme and 1∶1 prototype model of the three-bay and single-span flexible rock-shed was proposed and manufactured based on the research of the single-bay and single-span flexible rock-shed. The experiments on the three-bay and single-span flexible rock-shed were conducted under the impact of the rockfall with energy of 25kJ, 50kJ, 100kJ and 250kJ. It is shown that the flexible rock-shed can withstand the impact energy of less than 100kJ and can be reused without the necessity of maintenance of structural members; and can withstand the impact energy of about 250kJ and could be reused after some simple maintenance; and the clearance inside the flexible rock-shed satisfied the safety requirements. By employing dynamic strain rosettes, load cells and high-speed camera, the impact process of rockfall and dynamic response of the steel vaulted structure were recorded and tested. By combining with the test data, the deformation, the load transfer and the energy dissipation mechanism and the failure characteristics were analyzed. The weak position of the three-bay and single-span flexible rock-shed was pointed out and some improvement measures for the flexible rock-shed were suggested.