金沙江白鹤滩水电站柱状节理玄武岩 岩体变形特性研究

 金沙江白鹤滩水电站坝址区柱状节理玄武岩与一般柱状节理玄武岩相比，特点明显，其柱状节理起伏、不规则，柱体断面不规则且切割不完全，柱体内微裂隙发育，岩体内缓倾角构造结构面也较发育，岩体完整性较差，但呈断续镶嵌结构。在柱状节理玄武岩工程地质调查、岩体弹性波测试、多种现场岩体变形试验等工作基础上，系统分析了白鹤滩柱状节理玄武岩的基本力学特性和不同试验加载条件下的岩体变形机制。白鹤滩柱状节理玄武岩中发育的柱状节理、微裂隙及缓倾角结构面是导致岩体变形模量较低的主要因素；柱状节理玄武岩水平向变形模量明显大于铅直向变形模量，是由结构面发育特征和岩体应力状态决定的；新鲜柱状节理玄武岩中的柱状节理和微裂隙为硬性结构面，围压状态下呈闭合状，解除围压后易张开、松弛，保持围岩状态下柱状节理玄武岩仍具有较高的变形模量。

RESEARCH OF DEFORMATION CHARACTERISTICS OF COLUMNAR JOINTED BASALT AT BAIHETAN HYDROPOWER STATION ON JINSHA RIVER

Compared with the general columnar jointed basalt，the one at Baihetan Hydropower Station on the Jinsha River has significant characteristics as follows：undulating and irregular columnar joints，irregular and incomplete cutting columniation，microfissures enriched in the inner of columniation，gently dipping structural surface developed comparatively in basaltic mass，poor integrity but still intermittent mosaic structure in basaltic mass. Based on the engineering geological investigation and field experiments，the essential character and the deformation mechanism under different experimental conditions of loading on columnar basalt at Baihetan Hydropower Station are systematically analysed. Columnar joint，microfissure and gently dipping structural surface are the three fundamental factors which lead to the small deformation modulus of basaltic mass. The wide disparities in the horizontal and vertical direction of columnar jointed basalt¢s deformation modulus at Baihetan are determined by the structural surface and stress condition. Since columnar joints and microfissures are hard structural surface，they are closed under confining stress，but relaxed under unloading. Columnar basaltic mass maintains large deformation modulus in confining state.