中文摘要：

针对白鹤滩水电站柱状节理岩体陡峭结构面发育和卸荷开挖过程中垮塌与掉块问题突出的工程难题,在深入开展柱状节理岩体结构特征现场调查基础上,阐明了柱状节理岩体较为特殊的柱体状结构面网络、不规则多边形断面原生节理等特征及其形成原因,并通过现场钻孔摄像和声波测试揭示了柱状节理岩体在开挖卸荷后的岩体卸荷松弛和结构面开裂特性,并在此基础上探讨了柱状节理岩体的支护参数与开挖方案,其研究成果可为同类工程岩体开挖与支护设计借鉴。

英文摘要：

The unloading collapse and the falling of the columnar jointed rock mass have challenged the excavation and supporting design of underground tunnel in Baihetan Hydropower Station project.This paper presents the results of the characteristics and the mechanism of the columnar structural surface and the irregular shaped rock joints based on the detailed field rock mass investigation results.The in-situ rock features were revealed by the borehole camera and ultrasonic testing in order to develop the jointed rock supporting and excavation methods.These studies indicate that,after the excavation（unlading）,the structural planes are opened and the results provide experience in the supporting and excavation of the similar rock mass.