白鹤滩水电站层间错动带工程地质特性

白鹤滩水电站层间错动带结构松散、水理性质不良、力学性质差且延展范围广，是地下空间围岩体中的弱结构面，控制围岩体的变形破坏。在大量地质勘探及室内试验研究资料基础上，将白鹤滩工程区的层间错动带划分为节理带、劈理带和泥化带，有利于其力学特性的研究；在分类的基础之上，研究了C2、C4层间错动带中不同带区的形成模式、宏微观结构特征、矿物成分、水理性质以及剪切力学特性等主要工程地质问题，认为白鹤滩层间错动带主要是构造成因，不同带区在黏土矿物含量、微观结构以及水理性质等方面差异明显，错动带的剪切位移曲线整体呈理想弹塑性特征；分析了施工期层间错动带的地质特性对工程岩体的影响，含层间错动带围岩体主要存在3种破坏形式：块体塌落、剪切滑移与渗透破坏。

Engineering geological properties of interlayer staggered zones at Baihetan hydropower station

Interlayer staggered zones at Baihetan hydropower station are characterized as loose structures, poor water-physical properties, weak mechanical properties and large spatial distribution. The weak structural surfaces in the surrounding rock of underground space determine the deformation and failure of the surrounding rock mass. Based on a large number of geological exploration and experimental results of interlayer staggered zones in the Baihetan project area, they are divided into joint zones, lining zones and muddy zones. The formation mechanisms, macrostructural and microstructural features, mineral compositions, water-destructible properties and shearing mechanical properties in the C2 and C4 zones are studied. It is concluded that the interlayer staggered zones are mainly tectonic genesis, and the differences in clay mineral content, microstructure and hydrologic properties are obvious in different sub-zones. The shear mechanics curves of the interlayer staggered zones presents an ideal elastic-plastic. In the end, we analyze the effect of geological characteristics of interlayer staggered zones on the engineering rock mass during construction. Three main failure modes block collapse, shear slip, and seepage failure in the surrounding rock mass of underground powerhouses and caverns are observed.