坝基岩体开挖卸荷松弛效应工程特性研究

Study on Characteristics and Engineering Properties of in a Dam Hydropower Station

大岗山水电站位于大渡河中游,为混凝土双曲拱坝,坝高210m。由于河谷狭窄,谷坡高陡,地应力较高,坝基岩体开挖过程中产生了强烈的卸荷松弛。本文基于现场地质环境调查、声波检测,结合声波孔波速值和声波衰减率,分析了开挖卸荷松弛的典型特征及其松弛机理,归纳了卸荷松弛类型。通过分析岩体质量与检测成果在时间、空间上的关系得出了坝基岩体开挖卸荷松弛的时间、空间效应,并对坝基岩体开挖卸荷松弛时空效应与其建造、蚀变及构造的关系进行了地质分析研究。深入研究高拱坝建基岩体开挖松弛工程特性,可为高坝建基面的合理选择、松弛岩体工程处理提供科学依据。

The Dagangshan hydropower station is located in the middle reaches of the Dadu River,which is a concrete double curvature arch dam and dam height is 210 M. Because of the narrow valley,steep slopes and high ground stress,rock mass of dam foundation excavation process produces a strong unloading. Based on the field investigation of geological environment,acoustic detection,acoustic wave velocity value and combined with acoustic attenuation rate,the typical characteristics of excavation unloading relaxation and the relaxation mechanism were analyzed,the unloading relaxation type was summarized. Through the analysis of rock mass quality and test results in time and space,the rock mass of dam foundation excavation unloading relaxation time,the space effect,and the rock mass of dam foundation excavation unloading time effect relationship with construction,alteration and structure of geological analysis. Study of high arch dam foundation rock mass excavation engineering characteristics of relaxation can provide a scientific basis for a reasonable choice of surface and relaxation of rock mass engineering treatment.