比表面积是黏性土重要的物理化学指标,选择合适的测试方法是正确获得这一参数的前提。采用亚甲基蓝(Methylene Blue)吸附法、乙二醇乙醚(Ethylene Glycol Monoethyl Ether)吸附法、甘油(Glycerin)吸附法以及风干含水率经验公式对5种黏土的比表面积进行试验测定及估算,试验结果表明:对于不含蒙脱石的土样,各种方法测试结果较为一致,偏差较小;但对于含蒙脱石的土样,EGME法的试验结果比其他方法偏小较多。通过X衍射对各种吸附液饱和后的蒙脱石土样进行试验后发现,风干状态下蒙脱石的晶层间距d_(001)=15.6?,而经EGME法、甘油法、MB法饱和后d_(001)分别变为15.9?,17.5?,19.0?,蒙脱石的晶层在甘油及MB饱和后扩展明显,便于吸附分子进入晶层内表面,因此分子覆盖效果更好。统计分析表明,土的比表面积反映了土中各亲水性黏土矿物组分及相对比例的综合影响,因此比表面积与液限、塑性指数及活性等物性指标具有相关性,可用幂函数形式来拟合,而黏粒含量不能反映黏土矿物类型对比表面积的影响,因此当统计试样的黏粒中同时含有膨胀性和非膨胀性矿物时,比表面积与黏粒含量相关性较差。 Specific surface area is an important physical and chemical indicators of clay, select the appropriate test method is the premise of the correct access to this parameter. The specific surface area of ​​five kinds of clay was tested and estimated by Methylene Blue adsorption method, ethylene glycol ether (Ethylene Glycol Monoethyl Ether) adsorption method, Glycerin adsorption method and air drying moisture content empirical formula. The results showed that : For the samples without montmorillonite, the test results of the various methods are consistent and the deviation is small; however, the test results of EGME method are much smaller than those of other methods for smectite-bearing soil samples. The X-ray diffraction results show that the intergranular spacing of montmorillonite in air-dried state is d (001) = 15.6 ?, while that of EGM method, glycerol method and MB method After d_ (001) became 15.9 ?, 17.5 ?, 19.0? Respectively, the montmorillonite crystal layer expanded significantly after the saturation of glycerol and MB to facilitate the adsorption molecules entering the inner surface of the crystal layer, so that the molecular coverage is better. The statistical analysis shows that the specific surface area of ​​soil reflects the comprehensive influence of the relative proportions of the hydrophilic clay minerals in the soil. Therefore, the specific surface area is related to the physical property indexes such as liquid limit, plasticity index and activity and can be expressed by the power function However, the clay content does not reflect the influence of the clay mineral type on the surface area of ​​the clay. Therefore, the correlation between the specific surface area and clay content is poor when both the clay and the expansive and non-expansive minerals are contained in the clay samples.