: 黔张常铁路高山隧道高位穿越DIK53+678处巨型溶洞,为解决巨型溶洞内施工安全难题,通过地质勘察、无人机探测、危岩 体变形监测、危岩体振动速度监测和危岩体裂缝发展监测等多项措施对溶洞稳定性进行研究,结果表明溶洞内危岩分布广泛,溶洞 周壁多处危岩存在落石风险,在溶洞内施工需进行有效躲避和必要安全防护。 通过总结分析国内外多种落石冲击力计算方法,采 用《铁路工程设计技术手册·隧道》推荐的方法进行落石冲击力计算,计算得到落石冲击力达到442.1 kN,以此作为临时施工安全 防护的设计依据。 为保障施工安全,设计可移动式三角形钢结构防护棚架,经过结构优化,防护棚架可抵抗0.7 t落石自50 m高度 掉落的冲击荷载,满足巨型溶洞施工安全防护要求。

The Gaoshan Tunnel on Qianjiang-Zhangjiajie-Changde Railway passes through a giant karst cave at section DIK53+678. In order to safely and successfully cross the giant cave, the stability of the karst cave is studied by geological survey, UAV detection, deformation monitoring of dangerous rock mass, and vibration velocity monitoring and crack development monitoring of dangerous rock mass. The results show that dangerous rocks are widely distributed in karst caves, and there are many rockfalls around the cave wall; hence, effective evasion and necessary safety protection should be provided. Various calculating methods of rockfall impact force in China and other countries are summarized and analyzed. The rockfall load, reaching 442.1 kN, is calculated by using the method recommended in Railway Engineering Design Technical Manual: Tunnel, which is regarded as design reference for temporary construction protection. Based on the calculation results of the rockfall impact force, a triangular steel structure protective shed frame is proposed to against the impact of the rockfall in karst caves. After structural optimization, the protective shed frame can resist the impact load of 0.7 t falling rock from 50 m height, which can meet the safety protection requirements of the giant karst cave.