基于电阻率静力触探的海相黏土成因特性分析

土的电阻率是表征土体导电性的基本参数,也是反映土体固有物性的一个综合性指标。众所周知,土的电阻率影响因素较多,因此电阻率随深度的变化可以反映出土体的许多性状。电阻率静力触探(RCPT)作为一种新型的原位测试技术,除可测锥尖阻力、侧壁摩阻力和孔隙水压力以外,还可以同时测试土的电阻率。首先简要介绍了RCPT测试技术,采用电阻率静力触探(RCPT)在连云港海相黏土场地进行了试验,得到土的原位电阻率测试值。结合连云港海相黏土的室内物理化学分析试验,研究了其矿物成分、沉积化学特征,分析了该海相软黏土的电阻率指标与矿物成分、离子含量、胶结特性和氧化环境间的关系。分析表明:基于RCPT测试成果是可以充分反映出连云港海相黏土的成因特性的。

Analysis of formation characteristics of marine clay based on resistivity cone penetration test (RCPT)

The resistivity of soil is a basic parameter to describe its electrical conductivity and one of the primary physical properties of soil.The electrical resistivity is dependent on many properties of the soil,such as porosity,degree of saturation,composition(conductivity) of the pore fluid,mineralogy,shape,surface conductance and soil structure,including fabric,cementation and temperature.Therefore,the variation of soil electrical resistivity with depth can be an indicator of its characteristics.As a new kind of in-situ testing technique,the resistivity cone penetration test(RCPT) can be employed to measure the tip resistance,sleeve friction,pore pressure and soil resistivity simultaneously in the field.The measuring equipment and operation principle of the Vertek-Hogentogler RCPT system were introduced.Based on some literatures and field test results from the RCPT at Lianyungang in China,the interpretation of resistivity from depositional characteristics and ionic chemistry was presented.It was shown by the results obtained from field RCPT measurements and physicochemical tests that resistivity was obviously influenced by the depositional characteristics and ionic concentration.The test data indicated that the clay mineral percentage and ion concentration decreased with the increasing electrical resistivity.The Fe3+ concentration was also an indicative factor to have influence on the resistivity values.The Fe3+ existed as colloid in marine clay in Lianyungang,which might influence the cementation between soil particles.High content of Fe(OH)3 colloid could have a significant influence on the electrical characteristics of the clay.It could be concluded that the resistivity obtained from the RCPT could reflect the formation characteristics of marine clay in Lianyungang.