Si/Ca复合体系改性分散土的崩解特性及作用机制研究  

Disintegration characteristics and mechanism of dispersive soil modified by Si/Ca compound system

作　　者：刘翼飞 布泽凡 蔡东廷 樊恒辉[1,2] 张卓 茹含[1,2] 巨娟丽 LIU Yi-fei;BU Ze-fan;CAI Dong-ting;FAN Heng-hui;ZHANG Zhuo;RU Han;JU Juan-li(College of Water Resources and Architectural Engineering,Northwest A&F University,Yangling,Shaanxi 712100,China;Institute of Geotechnical Engineering/Museum of Problematic Rock and Soil,Northwest A&F University,Yangling,Shaanxi 712100,China;College of Acrospace Civil Engineering,Harbin Engineering University,Harbin,Heilongjiang 150001,China)

机构地区：[1]西北农林科技大学水利与建筑工程学院,陕西杨凌712100 [2]西北农林科技大学岩土工程研究所/特殊岩土博物馆,陕西杨凌712100 [3]哈尔滨工程大学航天与建筑工程学院,黑龙江哈尔滨150001

出　　处：《岩土力学》2023年第5期1341-1352,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.52079116,No.51579215,No.52108343)。

摘　　要：分散土具有遇水分散流失的特性,在工程实践中常采用石灰、水泥等进行改性,但存在环境污染等问题。选取纳米硅溶胶和氯化钙组成Si/Ca复合体系作为分散土的改性材料,采用针孔试验、泥球试验、分散崩解试验研究改性效果,通过物理化学性质等试验分析作用机制。试验结果表明,单一纳米硅溶胶在25%掺量下可完全消除分散性;单一氯化钙在0.40%掺量下可完全消除分散性;1%纳米硅溶胶与0.05%氯化钙组成的Si/Ca复合体系可完全消除土体分散性,有效减少单独使用两种材料的掺量。纳米硅溶胶改性土的崩解过程与分散土存在差异,其最终崩解时间较短,且崩解速率更稳定;与氯化钙共同作用时,最终崩解时间进一步缩短,崩解速率增大。Si/Ca复合体系改性分散土的作用机制包括降低土体的交换性钠离子百分比和pH、形成水化硅酸钙等。研究表明,由纳米硅溶胶和氯化钙组成Si/Ca复合体系可有效改性分散土。Dispersive soil has the characteristic of being dispersed and lost when encountering water.In engineering practice,lime and cement are often used to modify dispersive soil,but doing so often has such problems as environmental pollution.The Si/Ca compound system composed of nano-silica sol and calcium chloride is selected as the modified material for dispersive soil.The effect of the modification is studied by pinhole test,mud ball test,and dispersion and disintegration test.The mechanism of dispersive soil modified by Si/Ca compound system is explored by physical and chemical properties tests.The results show that the dispersibility of soil can be completely eliminated by using nano-silica sol alone at 25% dosage or using calcium chloride alone at 0.40% dosage.However,the Si/Ca compound system composed of 1% nano-silica sol and 0.05% calcium chloride can also completely eliminate the dispersion of soil,which effectively reduces the dosage of the two materials used alone.The disintegration process of the soil modified by nano-silica sol modified is different from that of dispersive soil,with a shorter final disintegration time and a more stable disintegration rate.The final disintegration time is further shortened and the disintegration rate increases when the nano-silica sol and calcium chloride are used together.The mechanism of dispersive soil modified by Si/Ca compound system includes reducing the percentage of exchangeable sodium ions and the pH of the soil,and generating calcium silicate hydrate.The results demonstrate that the Si/Ca compound system composed of nano silica sol and calcium chloride can effectively modify the dispersive soil.

关 键 词：分散土 纳米硅溶胶 氯化钙 崩解特性 改性机制 

分 类 号：TU411[建筑科学—岩土工程]