复合改良黄土状亚砂土强度特性及微观机制  

Strength Characteristics and Microscopic Mechanism of Composite Modified Loess-Like Sub-Sandy Soil

作　　者：李博[1] 石振武[1] 刘俊辰 张洪瑞 LI Bo;SHI Zhenwu;LIU Junchen;ZHANG Hongrui(School of Civil Engineering,Northeast Forestry University,Harbin 150036,China;Heilongjiang Jiaotou Highway Construction Investment Co.,Ltd.,Harbin 150069,China)

机构地区：[1]东北林业大学土木工程学院,哈尔滨150036 [2]黑龙江省交投公路建设投资有限公司,哈尔滨150069

出　　处：《硅酸盐通报》2023年第1期373-382,共10页Bulletin of the Chinese Ceramic Society

基　　金：黑龙江省交通投资集团有限公司科研项目(JT-100000-ZC-FW-2021-0121);黑龙江省交通运输厅科技项目(J-20181221)。

摘　　要：针对绥大高速公路病害问题,本文采用新型材料硅酸锂、石灰、聚丙烯纤维对黄土状亚砂土进行改良研究,通过冻融循环试验、X射线衍射(XRD)和扫描电子显微镜(SEM)研究了改良土的强度特性、微观机制、固化机理及孔隙结构。结果表明:增掺硅酸锂后可以大幅提升石灰改良土的无侧限抗压强度,复合改良土的最佳配合比为硅酸锂掺量3%(质量分数),石灰掺量6%(质量分数),聚丙烯纤维掺量0.4%(质量分数),纤维长度12 mm;复合改良土的破坏特征为“延性破坏”,聚丙烯纤维能够在受力过程中起到拉扯作用,使试件在一定应变范围内承受较大的应力;不论标准养护还是冻融循环环境,硅酸锂均能起到土体强度增强剂的作用,提供碱性环境,加剧水化反应,生成钠长石、C-A-S-H凝胶、Li[AlSi 4O 10]等新物质;水化产物的生成是土体孔隙相关参数下降的主要原因,标准养护环境及碱性环境能够促进水化反应的进行,加大孔隙参数下降幅度,有效提升改良土的强度。In order to solve the disease problem of Suida expressway,the loess-like sub-sandy soil was modified by the addition of new materials lithium silicate,lime and polypropylene fiber.The strength characteristic,microscopic mechanism,curing mechanism and pore structure of the modified soil were studied by the freeze-thaw cycle test,X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results show that the addition of lithium silicate can greatly improve the unconfined compressive strength of lime modified soil.The optimal mix ratio of composite modified soil is that:the content of lithium silicate is 3%(mass fraction),the content of lime is 6%(mass fraction),the content of polypropylene fiber is 0.4%(mass fraction)and the fiber length is 12 mm.The destructive form of composite modified soil is"ductile failure",and the polypropylene fiber plays a pulling role in its stress process,so that the specimen can withstand greater stress within a certain strain range.Regardless of whether the modified soil is in a standard conservation environment or a freeze-thaw cycle environment,lithium silicate can play the role of soil strength enhancer,provide an alkaline environment,intensify the hydration reaction,and generate new substances such as albite,C-A-S-H gel,Li[AlSi 4O 10]and so on.The formation of hydration products is the main reason for the decline of soil porosity related parameters.The standard conservation environment and alkaline environment can promote the hydration reaction,improve the decline of pore parameters,and effectively improve the strength of modified soil.

关 键 词：黄土状亚砂土 硅酸锂 强度特性 微观机制 孔隙结构 冻融特性 

分 类 号：TU444[建筑科学—岩土工程]