坝基岩体质量分级影响因素及分级标准

对于150 m以上级别的高坝、超高坝,坝基岩体质量分级以及大坝建基面选择对坝基工程处理、大坝体型设计以及坝型坝线比较等,均有决定性的控制作用。就水利水电工程项目而言,目前国内外采用的坝基岩体质量分级方法,主要有RMR分级系统、GSI分级、《工程岩体分级标准》(GB50218—2014)和《水利水电工程地质勘察规范(GB 50487—2008)》的相关标准。大量工程实践表明,影响坝基岩体质量的因素主要是岩石强度、岩体结构和赋存条件。结合新疆某工程坝基岩体质量分级研究,得出影响和制约该工程坝基岩体质量的主要因素为:岩石饱和抗压强度、岩体结构类型以及结构面性状特征(结构面组数、间距及结合程度)、风化与卸荷程度、声波波速、地震波波速、完整性系数、钻孔RQD和地下水状态等;据此,采用定性与定量相结合的方法,制定了坝基岩体质量分级标准。

Influence factors and classification standards for rock mass quality classification of dam foundation

For the dam above 150m height，dam foundation rock mass quality classification and selection has decisive effect to dam foundation control，dam body design and processing of dam line comparison. So far as water conservancy and hydropower projects are concerned，the main methods for the rock mass quality classification of dam foundation adopted at home and abroad are the relevant standards defined in RMR classification，GSI classification，“Standard for Engineering Classification of Rock Masses （GB50218—2014）” and “Code for Engineering Geological Investigation of Water Resources and Hydropower （GB50487—2008）”，etc. A large amount of engineering practices shows that the main factors of the influences on the quality of dam foundation rock mass are rock strength，rock mass structure and occurrence condition. In combination with the study on the quality classification of the dam foundation rock mass for a project in Xinjiang，the main factors to affect and restrict the quality of the foundation rock mass are obtained herein，i.e. rock-saturation compressive strength，rock mass structure types and their structural plane behaviors （number of structural plane group，space and bonding degree），weathering and unloading degrees，acoustic wave velocity，seismic wave velocity，integrity coefficient，RQD of drilling，ground water state，etc. On the basis of this，the dam foundation rock mass quality classification standards are established by the combination of both the qualitative method and the quantitative method.