花岗岩风化土孔压静力触探(CPTU)数据特征及风化状态划分

Characteristics of Piezocone Penetration Test(CPTU)Data and Division of Weathering State of Weathered Granite Soil

文章梳理了基于孔压静力触探测试(CPTU)进行土分类的主要方法,以及国内主要规范的应用情况,指出当前缺乏针对花岗岩风化土的CPTU数据特征研究。对广州地区3个工程项目的花岗岩风化土CPTU测试数据,对照CPTU数据曲线的基本特征,分别用土类指数法、线性分类法和水运工程分类法进行分类,发现主体数据利用土类指数法可通过Q_(tn)~F_(r)图中lgQ_(m)=2.2-1.8×lgF_(r)分界线的位置关系,可基本判定土体是否属于花岗岩风化土;通过线性分类法的Bq~qT土分类图能较好地判定花岗岩风化土的土性特点,但会把一部分含粗颗粒较多的粉质黏土或黏土判定为砂土;水运工程分类法中的Q_(tn)~F_(r)图在花岗岩风化土风化状态划分中有较好的参考作用,残积土、全风化和强风化之间的界线大约为Q_(tn)=59和109。研究表明CPTU可以用于区分花岗岩风化土和一般沉积土,也可以用于花岗岩风化土风化程度的划分。

The main methods of soil classification based on piezocone penetration test(CPTU)and their application in major domestic codes are reviewed.It is pointed out that there is a lack of research on the characteristics of CPTU data around weathered granite soil.According to the research conducted on the CPTU test data of granite weathered soil of three engineering projects,it can be determined whether the soil mass belongs to granite weathered soil by comparing the basic characteristics of the CPTU data curve and the orientation of its main data relative to the boundary lgQ_(tn)=2.2-1.8×lgF_(r) in the Qtn~F_(r) soil classification map.The B_(q)~q_(T) soil classification map can better judge the soil characteristics of weathered granite soil,but it will judge some silty clay or clay with many coarse particles as sand;The Qtn~F_(r) map has a good reference role in the division of weathered state of granite weathered soil.The boundary between residual soil,completely and strongly weathered rock is roughly Q_(tn)=59 and 109.The results show that CPTU can be used to distinguish granite weathering soil from general sedimentary soil,and can also estimate the weathering degree of granite weathering soil.