大岗山水电站坝基岩体表层低波速带成因分析

Causal analysis for low wave-velocity zone at dam foundation of Dagangshan Hydropower Station

采用声波测试方法对大岗山水电站坝基岩体开挖完成后的岩体质量进行评价。因坝基岩体受开挖爆破、卸荷松弛及地质构造缺陷等因素的影响,岩体表层会出现不同深度的低波速带。通过对其表层低波速深度与爆破松弛深度以及表层低波速带深度等值线与地质构造的对比,分析了坝基岩体表层低波速带产生的原因及表层低波速带局部深度异常原因。

Acoustic wave test was adopted for excavation quality evaluation of dam foundation rock mass at Dagangshan Hydropower Station. Different level low wave-velocity zones were found at the superficial rock layer due to explosive influence,unloading relaxation as well as geological faults. Through comparing low wave-velocity depth,explosive relaxation depth and contour of low wave-velocity with geological structure,the genesis of low wave-velocity rock zone and its local depth anomaly are discussed.