电渗-纳米蒙脱土加固淤泥质黏土的试验研究

Experimental study on the effect of electroosmosis incorporated with nano-montmorillonite reinforcing mucky clay

【目的】电渗处理可以加速淤泥质黏土的排水固结,但也存在着加固效果不均匀、加固强度有限等问题。为改善淤泥质黏土的电渗固结效果,提升电渗技术在实际工程中的应用【方法】以广州南沙区典型淤泥质黏土为研究对象,利用自制装置进行室内电渗模型试验,分别添加质量分数为0%、1%、2%、3%的纳米蒙脱土,通过监测电渗过程中各试验组电流和排水量随时间的变化,测定电渗前后土体的液塑限、抗剪强度、孔隙比和微观结构差异,探讨添加纳米蒙脱土对电渗固结淤泥质黏土效果的影响。【结果】结果显示,蒙脱土含量为1%、2%和3%的电渗组阴极土体黏聚力分别提高了33.9%、67.9%和80.4%,内摩擦角分别提高了16.8%、30.1%和31.8%,而孔隙比则从1.18下降到了1.01、0.98和0.92,且随着纳米蒙脱土含量的增加,土样微观结构从粒状向层状团聚体转变。【结论】电渗联合纳米蒙脱土处理可以显著改善淤泥质黏土的物理力学特性,随着纳米蒙脱土含量的增加,处理后的土样微观结构更加密实,但纳米蒙脱土的加入不利于电渗排水,随着蒙脱土含量的增加电渗排水量降低。

[Objective]Although electroosmosis can facilitate the dewatering of mucky clay,several issues remain with this novel method,such as the nonuniformity and limitation of reinforcement.In order to improve the electroosmotic consolidation effect,promoting its applications in practical engineering,the typical silty clay obtained from Guangzhou nansha district is used in the experimental study.[Methods]A series of laboratory tests are carried out in a customized apparatus to explore the simultaneous effect of electroosmosis incorporating with nano-montmorillonite.The mass fractions of nano-montmorillonite are set as 0%,1%,2%and 3%of dry soil.During the process of electroosmotic treatment,the temporal evolution of electric current and drainage are monitored periodically.Also,the differences in liquid and plastic limit,soil shear strength and microstructure are studied.[Results]The result indicate that the cohesion of cathodic soil treated with 1%,2%and 3%nano-montmorillonite is increased by 33.9%,67.9%and 80.4%,respectively.And the corresponding internal frictional angle is increased by 16.8%,30.1%and 31.8%.While the void ratio decreases from 1.18 to 1.01,0.98 and 0.92.In addition,with the increase of nano-montmorillonite content,the granular soil particles are bonded to form layered aggregates.[Conclusion]Electroosmosis incorporating with nano-montmorillonite has significant effect on improving the physical and mechanical properties of mucky clay.With the increase of nano-montmorillonite content,the microstructure of treated soil samples become more dense.While the addition of nano-montmorillonite causes the decrease of electroosmotic drainage.The final drainage decreases with the increase of nano-montmorillonite content.