吸附离子对粉质粘土及改良土特性的影响

Effects of cation adsorption on properties of silt clay and mixed dredged soil

利用疏浚土有机质含量高、吸附能力强和低渗透性等特点,探讨将其作为填埋场黏土衬垫改性材料的可能性。针对粘土垫层所关心渗透性及强度两个基本问题,比较了粉质黏土、改良土(粉质黏土添加疏浚土)吸附离子前后的变化。吸附K+、Cu2+后粉质黏土、改良土的渗透系数随着土中离子含量的增加而增大,但对改良土渗透系数的影响要小于粉质黏土;吸附离子后,粉质黏土摩擦角增幅不大,黏聚力有较大增长,而改良土的黏聚力增长较少,摩擦角增长较快。总体而言,添加一定量的疏浚土能改善吸附离子对黏土垫层的影响。采用SEM电镜试验拍摄了离子吸附前后土体微观结构的变化,并从扩散双电层理论出发,解释了吸附离子对粉质黏土及改良土的影响。

Due to the high organic content,strong adsorption capacity and low permeability,dredged soil can be used as a kind of additive to clay liner of landfills.The changes of physico-mechanical properties of the silt clay and the mixed soil（silt mixed with dredged soil） before and after cation adsorption have been investigated.The permeability and shear strength,two basic issues of the quality of clay liner,have also been studied.The hydraulic conductivities of the crude soil and the mixed soil increase with increasing quantity of cation adsorption on the soils.However,the hydraulic conductivities of the mixed soil is less apt to be influenced than that of the silt.After adsorbed with cations,both the frictional angle and the cohesion force of the silt clay and the mixed soils increased at first and then reached a peak,whereas the increases of the cohesion force of the silt clay as well as the frictional angle of the mixed soil were comparatively more.In a word,the addition of dredge to silt could improve the effect of cation adsorption on permeability and strength of soil.SEM photo were conducted to evaluate the changes of microstructure of soils.The relevant impacts were further discussed by means of electrostatic double layer theory.