乌东德水电站坝址区河床深厚覆盖层组成与结构地质勘察研究

COMPOSITION AND STRUCTURE OF GEOLOGICAL PROSPECTING IN RIVER DEEP OVERBURDEN LAYERS AT DAM SITE OF WUDONGDE HYDROPOWER STATION

河床深厚覆盖层勘探取样与试验研究是我国西部水电工程勘察中最常见技术难题之一。金沙江乌东德水电站坝址区河床覆盖层厚度较大、成因多样、组成混杂、结构不均,高围堰与深基坑稳定问题突出。为此,作者所在单位开展了专题研究工作,在勘探取样技术与原位测试方法上进行了探索与创新——为获得原状样而专门研制了单管与双管内筒式锤击取样器,为弥补钻探取样之不足而将可视化技术(如钻孔数字彩电、孔间电磁波CT)与常规物探方法(如地震法勘探、钻孔声波测试)相结合创新性开展原位测试,全面查明了河床覆盖层的组成及结构,开辟了河床深厚覆盖层地质勘察研究的新途径,不仅为河床深厚覆盖层工程特性室内试验研究提供了前提,而且为高围堰与深基坑稳定问题地质分析、工程评价及设计处理提供了充分可靠的地质依据,可为类似工程地质勘察研究所借鉴。

The exploration,sampling and in-situ testing at river beds are one of the most common technical problems associated with hydropower projects in China.The Jinsha River Wudongde Hydropower Station Dam Area has the problems of the riverbed overburden thickness,composition,structure,genetic diversity of hybrid uneven, high cofferdam and deep foundation pit stability.Therefore,we carried out special research work on exploration and sampling technique and in-situ test method.We obtain undisturbed samples with specially developed for single and double tube type hammer.The method makes up for the deficiency of drilling sampling and visualization technology (such as borehole digital TV,hole drilling electromagnetic wave CT)and conventional geophysical methods(such as seismic exploration,borehole acoustic test)combined with the creative development of in situ test.They are comprehensive to identify the composition and structure of river bed overburden and riverbed deep cover.They open up a new path on the layer geological investigation.The engineering properties of layer provides the premise and analysis for the geological high cofferdam and deep foundation pit stability evaluation.The treatment engineering design provides the geological basis with sufficient reliability.They can be used for reference in similar engineering geological investigation.