泥水盾构开挖面渗透带土体电阻率特性试验研究

泥浆渗透是泥水盾构开挖面成膜的关键过程，土体电阻率表征方法能够及时、有效反映泥浆渗透状态。采用二电极交流电法电阻率测试仪对泥浆 土体混合物的电阻率进行了测试，研究了孔隙水、CMC(羧甲基纤维素钠)、电极间距和泥浆浓度等因素对土体电阻率的影响。结果表明：土体电阻率随泥浆浓度增大而减小；海水和CMC的掺入将降低土体电阻率，但两者对膨润土颗粒的作用机理有所不同，海水的掺入导致膨润土颗粒发生絮凝和团聚，而CMC的掺入将使泥浆中离子的定向迁移能力增强；接触电阻亦对土体电阻率产生影响，为了获得可靠的土体电阻率测试值，应进行多次不同电极距离的测试。

Electrical resistivity characteristics of infiltration zone on slurry shield face#br#

Slurry penetration is the key process of filter-cake formation on excavation face of slurry shield. The characterization methods of soil electrical resistivity can reflect the state of slurry penetration timely and effectively. The electrical resistivity of soil-slurry mixtures were tested by resistivity measurement devices using the two-electrode AC (alternating current) electrical method. The influence of pore water, CMC (sodium carboxymethylcellulose), particle gradation of soil, electrodes distance and slurry concentration on soil electrical resistivity was studied. The results indicate that, the electrical resistivity of soil decreased with increasing of slurry concentration; seawater and CMC both induced the decreasing of soil electrical resistivity, but the action mechanisms of seawater and CMC on bentonite particles are different. The addition of seawater makes the phenomenon of flocculation and aggregation of bentonite particles, and the addition of CMC enhances the ability of ion directed migration in slurry. Contact resistance can also influence on soil electrical resistivity. In order to gaining the reliable soil electrical resistivity, the test should be conducted more than once with different electrode distance.