病险老土石坝坝基可液化土标贯判别方法修正研究  

CORRECTION RESEARCH OF STANDARD PENETRATION METHOD FOR IDENTIFYING LIQUEFIABLE LAYER OF DANGEROUS-OLD EARTH-ROCK DAM FOUNDATION

作　　者：赵留园 段伟锋 曹强 ZHAO Liuyuan;DUAN Weifeng;CAO Qiang(PowerChina Huadong Engineering Corporation Limited,Hangzhou 311122,China;Zhejiang Huadong Geotechnical Investigation&Design Institute Corporation Limited,Hangzhou 310004,China)

机构地区：[1]中国电建集团华东勘测设计研究院有限公司,杭州311122 [2]浙江华东岩土勘察设计研究院有限公司,杭州310004

出　　处：《工程地质学报》2024年第5期1779-1786,共8页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:42102313);华东院科技项目(资助号:KY2021-KC-02-03)。

摘　　要：“十四五”期间,我国近2万座病险水库需开展安全鉴定及除险加固工作,地震液化判别是其中的重要勘察内容,相关国家规范多推荐采用标准贯入试验(SPT)进行液化判别。但是这些规范方法对于已建成的病险老土石坝坝基可液化层判别并不完全适用,主要原因在于其只指出水库水位变化后需修正实测标贯击数,但是如何得到用于标贯击数修正的坝体地下水位并无相关说明。而病险水库运行水位一般低于正常蓄水位,坝体钻孔的地下水位埋深较大,故实测标贯击数偏大、临界标贯击数偏小,液化判别偏于危险。本文结合实际工程需要,提出了坝体钻孔地下水位快速修正方法,主要思想是先将孔内水位进行抬升(抬升最大幅值为正常蓄水位与当前蓄水位之差),然后结合孔口高程、坝高等对孔内水位进行适当折减。最后介绍了该修正方法在部分土石坝安全鉴定工程中的应用。所提出的方法是对现行规范中液化判别内容的补充,已在实际工程中得到较好运用,所积累的工程经验可为病险水库的安全鉴定及除险加固工作提供参考。The seismic liquefaction discrimination is an important survey content in hydropower engineering and other fields.In relevant national codes,the standard penetration test(SPT)is recommended for liquefaction discrimination.However,the methods in these specifications are not fully applicable to the discrimination of the liquefiable layer of the dam foundation for dangerous old earth-rock dams.The main reason is that in water conservancy and hydropower projects,it is only pointed out that the measured SPT blow count and critical SPT blow count need to be corrected after considering the change of reservoir water level,but there is no relevant explanation on how to obtain the underground water level of the dam body for SPT blow count correction.The water level of the dangerous reservoir is generally lower than the normal pool level,and the buried depth of the groundwater level of the boreholes in the dam body is large,thus the measured SPT blow counts are large,and the calculated critical SPT blow count value is too small,and the liquefaction discrimination may be dangerous.Combined with the needs of practical engineering,this paper puts forward the rapid correction method of dam groundwater level.The main idea is to raise the water level in the hole(the maximum amplitude is the difference between the normal water level and the current water level),and then reduce the water level in the hole in combination with the elevation of the boreholes and the height of the dam.Finally,it introduces a series of correction studies of this method in some earth-rock dam safety appraisal projects,which is a supplement to the liquefaction discrimination for the current code,and has been well used in practical projects.The accumulated engineering experience can provide reference for safety assessment and reinforcement of nearly 20,000 dangerous reservoirs in China during“the 14th Five-Year”period.

关 键 词：土石坝安全鉴定 地震液化 坝基 标准贯入试验 

分 类 号：TV16[水利工程]