乌东德水电站拱坝坝基岩体松弛特征研究

Study on Rock Mass Relaxation Characteristics of Arch Dam Foundation of Wudongde Hydropower Station

高拱坝巨大荷载直接面对的是坝基表层卸荷松弛岩体,研究坝基卸荷后松弛岩体的特征,合理评价其影响并提出处理建议是拱坝建设中的关键。基于乌东德坝基工程地质条件,在详细调查建基面的基础上,综合利用高清电视、单孔声波测试等方法,深入研究乌东德水电站坝基岩体开挖后岩体卸荷变形特征、卸荷松弛深度、卸荷松弛程度及卸荷松弛时间效应等特征。基于坝基岩体的卸荷松弛特征及卸荷作用的时间、空间分布规律,认为乌东德坝基岩体卸荷松弛主要为开挖卸载后低地应力条件下的回弹所致,主要表现为沿已有结构面的张开,松弛深度及松弛度在一定时间后趋于稳定,不影响边坡整体稳定性,且表层卸荷松弛岩体具有较好的可灌性和灌浆效果,不需二次清挖即可满足大坝建基岩体质量要求。

The huge load ol the high arch dam is directly facing the dam foundation surface unloading relaxation rock, the study ol dam foundation unloading relaxation rock characteristics, the reasonable impact evaluation and the proposed con-struction ol arch dam construction are the key engineering geological problems. Based on the geological conditions ol Wu-dongde dam foundation,and the detailed geological survey ol the foundation surface, the paper deeply studies the unloa-ding deformation characteristics,unloading relaxation depth, degree, time and spatial effect, and so on, after the dam foun-dation rock mass excavation of the Wudongde Hydropower Station by using the high-definition television and single-hole acoustic wave test. It is concluded that the unloading relaxation of the Wudongde dam foundation is mainly due to the re-bound after excavation and unloading under low geostress conditions. It is mainly manifested as the opening of the existing structural plane,the relaxation depth and slackness become stable after a certain time,which is the normal unloading and relaxation deformation of the rocky high slope without affecting the overall slope stability, and the surface unloading relax-ation rock mass has good irrigation and grouting effect,without secondary excavation, riverbed foundation has been com-pleted local grouting results also verify this conclusion. The research results provide scientific basis for the relaxation rock engineering,speed up the construction progress, reduce the project investment, enrich the practice of high arch dam foun-dation engineering,and have important reference to similar projects.