为了分析隧道爆破振动引起的溶洞落石风险,以湖北新建高铁黔张常线路高山隧道揭露的巨型干溶洞为研究对象,首先对溶洞进行无人机探测与三维激光扫描测绘,并以三维激光扫描仪监测分析溶洞稳定性,随后以引发溶洞落石频发的掘进爆破扰动效应为重点研究内容,建立溶洞危岩体爆破振动监测系统,获得溶洞表面质点爆破振动速度.结合萨道夫斯基标准公式,给出溶洞表面岩体的爆破振动速度计算公式,分析爆破扰动作用下溶洞落石规律及危岩体裂缝发展规律.主要结论如下:1)巨型溶洞表面岩体允许的爆破振动速度为1 cm/s,隧道掘进爆破引发的质点振动速度超过该值时溶洞就会出现落石,超过1.5cm/s时溶洞就会出现多范围大体积落石;2)为保证溶洞作业期间的人员和设备安全,预防落石风险,采用钢管柱+H型钢梁组成的满堂支架安全防护体系支护溶洞,具有良好的支护效果.%The Gaoshan Tunnel blasting vibration induced rockfali of a giant dry karst cave on Qianjiang-Zhangjiajie-Changde High-speed Railway is dangerous and needs to be analyzed.As a result,the unmanned aerial vehicle detection,3D laser scanning surveying and 3 D laser scanner analysis are carried out.And then the blasting vibration monitoring system is established for dangerous rock of the karst cave by regarding the tunnel blasting vibration effect as the key item to acquire the blasting vibration velocity of the particle on karst cave surface.Finally,the calculation formula for blasting vibration velocity of rock of karst cave is given based on Sadaovsk formula;and the law of rockfall and the development rule of dangerous rock crack width are analyzed.Some main conclusions are drawn as follows:1) The allowable blasting vibration velocity of giant karst cave rock is 1 cm/s;rockfall would occur when the particle vibration velocity exceeds 1 cm/s;and large volume rockfall would occurs when the particle vibration velocity exceeds 1.5 cm/s.2) A full support system of steel tube column + H-shaped steel beam is used to guarantee the safety of the personnel and equipments during construction;and good effect has been achieved.
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