锦屏一级左岸垫座以下坝基地质缺陷初步评价

PRELIMINARY EVALUATION OF GEOLOGICAL DEFECTS FOR ROCK FOUNDATION BELOW LEFT BANK PEDESTAL OF ARC DAM FOR JINPING Ⅰ POWER-STATION

锦屏一级左岸垫座以下发育的不良地质单元,不仅破坏其岩体的完整性,而且可能导致建基面抗变形能力的不均匀性,以致对坝基岩体带来不良影响,危及拱坝安全。立足于坝基岩体质量环境,将垫座以下不良地质体划分为内倾顺层构造带,陡倾切层构造带,溶蚀裂隙带等三大综合缺陷类型,并阐述了各类缺陷的性状及其对坝基完整性、均匀性、变形性等方面的控制作用,分析了其典型声波曲线的波速量值及衰减特征。由此,按"轻度"、"中等"、"强烈"三个等级,定性的分区评价了各部位缺陷对坝基岩体的影响程度。着重认为f2断层附近,规模较大、间距较小、波速值低(2500-3500m·s-1)的内倾顺层构造带,不仅控制着岩体的抗剪性能,而且对坝基变形分异和基地应力分布存在"强烈"影响,应对其进行单独处理。

The adverse geologic elements within the dam foundation below left pedestal of the jinping I project cause not only the disruption of rock mass in integrity,but also the nonhomogeneous deformation of foundation interface,which can endanger the safety of the arc dam.Based upon their environments of rock masses qualities,the geologic defects are classified into three major classes： the anaclinal and bed-paralleled structural zone,the steep dipping and cross-bedding structural zone and the Karst fracture zone.Furthermore,the control action of the various geologic defects on the dam foundation in integrity,homogeneity,and deformation is discussed.The wave velocity and attenuation characteristic of their typical speed curves of sonic wave are also analyzed. Thereby,the qualitative evaluation of the influence degree of geologic defect to rock masses in dam foundation is made by zoning in order of＂slightly＂,＂moderately＂and＂highly＂rates. And the conclusions emphasize that the anaclinal and bed-paralleled structural zones are large scale,and have small spacing and low wave velocity value（2500～3500m·s^-1） near the fault f2.The zones not only control over the shearing properties of rock masses,but also have a highly-degree influence on the differential deformation and the stress distribution of the dam foundation,which should be deal with separately.