混入聚丙烯纤维电渗法加固波士顿蓝黏土模型试验

    IMPROVEMENT OF BOSTON BLUE CLAY USING ELECTROOSMOTIC CONSOLIDATION WITH POLYPROPYLENE FIBERS: A MODEL EXPERIMENT

    • 摘要: 电渗固结法是一种软黏土地基处理方法。但是,单纯采用电渗固结法会导致土体中产生裂缝,减少电渗渗流通道,影响地基处理效果。基于此,本文在波士顿蓝黏土中混入不同含量的聚丙烯纤维,联合电渗法对其进行加固,以克服原有方法的缺陷。本文采用自制的电渗固结试验系统开展模型试验,试验过程中监测土体电流、电势分布、排水量和裂缝扩展,试验完成后测量土体的pH值、Cl-摩尔浓度、含水量和不排水抗剪强度。结合以上试验数据并依托电渗固结理论、电导理论、离子运移理论、电解理论对混入聚丙烯纤维电渗法实施过程进行全面分析,得出以下试验结果和结论:(1)电渗固结过程中产生的吸力会造成波士顿蓝黏土中出现裂缝,混入0.05%和0.1%的聚丙烯纤维可以减小裂缝扩展程度,而混入0.15%和0.2%的聚丙烯纤维可以有效消除裂缝;(2)在土体中混入聚丙烯纤维有利于离子运移和电解水过程混入聚丙烯纤维之后,土体阳极附近的pH值变低、Cl-摩尔浓度变高;(3)随着聚丙烯纤维的混入,可显著提高波士顿蓝黏土的电渗渗流量和排水量。电渗固结完成后,聚丙烯纤维含量为0.2%条件下的最大不排水抗剪强度值,比不掺入聚丙烯纤维时提高477.8%。

       

      Abstract: Electro-osmotic consolidation method is a foundation treatment method for soft clay. However,electro-osmotic consolidation may cause the cracks generation in soft clay,which will reduce the electro-osmotic flow channel and the electro-osmotic consolidation effect. Therefore,this paper mixed polypropylene fiber with Boston blue clay during the electro-osmotic consolidation,which improved the reinforcement effect. In this paper,a self-made electro-osmotic consolidation test system was used to monitor the current,potential distribution,water content and crack generation during electro-osmotic consolidation. After electro-osmotic consolidation,the pH value,Cl- molar concentration,water content and undrained shear strength distribution of Boston blue clay were measured. Based on the electro-osmotic consolidation theory,conductivity theory,ion transport theory and electrolysis theory,the results and conclusions are as follows: (1)The suction generated in the process of electro-osmotic consolidation will cause cracks in Boston blue clay,and mixing 0.05% and 0.1% polypropylene fiber can reduce the degree of crack propagation. Moreover,cracks can be eliminated by mixing 0.15% and 0.2% polypropylene fiber; (2)During the electro-osmotic consolidation,the mixing of polypropylene fiber is beneficial to ion migration and electrolysis reaction. The results show that the pH value decreasing and the Cl-molar concentration increasing were observed near the anode after mixing polypropylene fiber; (3)With the mixing of polypropylene fiber,the electro-osmotic flow and drainage of Boston blue clay can be significantly increased. After the electro-osmotic consolidation,the maximum undrained shear strength of 0.2% polypropylene fiber is 477.8% higher than that of 0% polypropylene fiber.

       

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