摘要
针对不同养护龄期对于粉煤灰水泥土抗剪强度影响的问题,采用不固结不排水三轴剪切试验从宏观力学的角度分析养护龄期对粉煤灰水泥土的影响,结合SEM试验和XRD试验从微观角度分析试样内部结构与物质成分。试验结果表明:从宏观角度分析,粉煤灰水泥土的应力-应变曲线呈现应变软化型,试样的抗剪强度随养护龄期的增加逐渐增大且28 d的抗剪强度最大,同时,由于试样内部各物质之间的反应随养护龄期的增加而持续进行,龄期越长试样内部各物质之间的胶结作用越强,致使试样的内摩擦角和黏聚力随养护龄期逐渐增大;从微观角度分析,试样内部生成的结晶物质(钙矾石)与胶凝物质(C-S-H凝胶)等填充试样内部的大孔隙且相互黏结,导致试样愈加密实,抗剪强度增大。本文旨在为粉煤灰等材料固化黄土的抗剪强度提供试验依据,为粉煤灰等工业副产品在工程中的应用提供参考,对粉煤灰的利用和环境保护具有参考意义。
In Qinghai,the loess is widely distributed and coal reserves are rich.Rapid consumption of coal resources leads to increased production of fly ash.Therefore,many scholars have studied fly ash as a cementitious material and added it to cement soil.The shear strength of fly ash cement soil is poor.At the same time,due to the problems of loess collapsibility,the strength of fly ash cement soil can rapidly decrease.This paper aims at the influence of different curing ages on the shear strength of fly ash cement soil.It carries out unconsolidated and undrained triaxial shear tests to analyze the effect of curing age on fly ash cement soil from the perspective of macro mechanics.It combines with SEM test and XRD test to analyze the internal structure and material composition of the specimen from a microscopic perspective.Experimental results show that:from a macro perspective,the overall stress-strain curve of fly ash cement soil shows strain softening.The shear strength of the sample gradually increases with the increase of curing age and the shear strength is the largest at the 28 days.Simultaneously,due to the increase of the curing age,the mutual chemical reactions between the substances in the sample can continue.The longer the curing age of the sample,the stronger the cementation between the substances inside the sample,which can cause the internal friction angle and cohesive force of the sample to gradually increase.From a micro perspective,with the extension of curing time,the crystalline material(Ettringite)and gelling material(C-S-H gel)generated inside the sample can fill the large pores inside the sample.These materials can adhere to each other,and cause the sample to become denser and the shear strength increases.This paper provides a test basis for the shear strength of solidified loess with fly ash and other materials,offers reference for the application of industrial by-products such as fly ash in engineering,and has reference significance for the utilization of fly ash and environmental protection.
作者
解邦龙
张吾渝
张丙印
季港澳
崔靖俞
XIE Banglong;ZHANG Wuyu;ZHANG Bingyin;JI Gang'ao;CUI Jingyu(College of Civil Engineering,Qinghai University,Xining 810016,China;Qinghai Key Laboratory of Building Energy Saving Materials and Engineering Safety,Xining 810016,China;School of Civil Engineering,Tsinghua University,Beijing 100084,China)
出处
《工程地质学报》
CSCD
北大核心
2021年第4期1216-1223,共8页
Journal of Engineering Geology
基金
青海省科技厅项目(资助号:2017-ZJ-792)
国家自然科学基金项目(资助号:51768060)
青海省创新服务平台建设专项
青海大学中青年基金项目(资助号:2018-QGY-5)。
关键词
土的抗剪强度试验
粉煤灰水泥土
X射线衍射
扫描电镜试验
Soil shear strength test
Fly ash cement soil
X-ray diffraction
Scanning electron microscope test
