苏通大桥地基中深厚软土电阻率试验研究

Experimental study on electrical resistivity of thick soft soil in foundation of Su-Tong Yangtze River Bridge

通过室内电阻率试验和土工试验,对长江下游苏州-南通长江公路大桥地基中深厚软土电阻率特征及其与物理力学参数的相关关系问题进行了研究。发现,(1)在同一钻孔(即CZK30)中,从粉质黏土→粉砂→细砂→中粗砂,土样的电阻率逐渐增大。电阻率随含水率、孔隙比、饱和度的增加而减小,而随垂直渗透系数、水平渗透系数、压缩模量、标贯等的增加而增大。(2)CZK30孔中粉质黏土电阻率随含水率、孔隙比、饱和度、压缩系数、液限系数增加而减小,而随压缩模量、黏聚力等的增加而增大。(3)通过拟合,提供了软土电阻率与物理力学参数相关关系的量化表达式,拟合曲线与试验数据点的相关程度较高,相关系数绝大部分在0.88以上。结果表明,土电阻率与其它物理力学参数间存在密切的联系。

Through electrical resistivity experiments and geotechnical experiments, the characteristics of electrical resistivity of thick soft soil layer and the correlativity between electrical resistivity and engineering mechanical parameters in the foundation of Suzhou-Nantong Yangtze River Bridge in China＇s Jiangsu Province, were studied. It was found that, firstly, in CZK30 bore, from clay →powdery sand→thin sand→medium and coarse sand, the electrical resistivity of soil sample increased gradually, the electrical resistivity decreased with the increase of water content, void ratio and saturation, and increased with the increase of the vertical and horizontal infiltration coefficient, compression modulus and standard penetration test （STP）; secondly, in CZK30 bore, electrical resistivity of clay soil decreased with the increase of the water content, void ratio, saturation, compression coefficient, liquid coefficient, and increased with the increase of compression modulus and cohesion; thirdly, through linear and polynomial fit, the mathematic expressions between electrical resistivity and engineering mechanical parameters .of soil were offered, and the correlativity coefficients were high （larger than 0.88 mostly）. The following conclusions can be drawn that there exist affinity between electrical resistivity and other physical and mechanical parameters.