白鹤滩层间错动带微结构特性及其化学改性初探

Preliminary study of microstructural properties and chemical modifications of interlayer shear weakness zone in Baihetan

白鹤滩水电站层间错动带结构疏松、性状软弱、空间展布范围大、力学强度低,严重影响着地下厂房洞室的稳定性。为了揭示并改良层间错动带的力学特性,首先通过矿物成分分析试验、扫描电镜试验和压汞试验,从微观结构角度对层间错动带的矿物组成特征、颗粒排列规律、孔隙分布规律进行了详细的研究,阐明了层间错动带的微观结构特性及其对灌浆材料选择的影响,进而开展了层间错动带化学溶液浸泡对比试验。试验表明,硅酸钠溶液可以有效改善层间错动带的完整性,明显提高层间错动带的弹性波速、抗压强度、弹性模量和凝聚力。其研究结果对白鹤滩层间错动带的工程加固和改性设计具有一定的借鉴意义。

Interlayer shear weakness zone has a series of features such as loose structure, easy to be softening, large spatial distribution and poor mechanical properties in Baihetan hydropower station. The existence of interlayer shear weakness zone seriously affects the stability of underground cavern groups of hydropower station. In order to reveal and improve the mechanical properties of interlayer shear weakness zone, X-ray diffractometer, scanning electron microscope and mercury intrusion porosimetry tests are applied separately to observe and determine the main mineral composition, the orientated range of particles and the distribution of pore structure in samples. Microstructural properties of interlayer shear weakness zone and its effect on the selection of grouting materials are discussed in detail combining with the testing data. What＇s more, chemical modification experiments are carried out based on above experiments. Comparative experiment between samples immersed with or without sodium silicate solution indicates that chemical modification can improve the integrality, elastic wave velocity, compressive strength, elastic modulus and cohesion of interlayer shear weakness zone effectively. These cognitions can provide some useful means for the engineering reinforcement and modification design of interlayer shear weakness zones in Baihetan hydropower station.