摘要
【目的】以青海西宁地区黄土为研究对象,探究冻融循环作用下木质素改良黄土的力学性能及微观机理。【方法】通过封闭系统条件下对木质素改良土进行冻融循环试验,开展基本物性试验、无侧限抗压强度试验、热学试验,综合评价木质素磺酸钙(CL)、木质素磺酸钠(SL)和无磺木质素(SFL)对黄土的加固效果,结合扫描电镜和X射线衍射对土体结构与成分进行分析。【结果】结果显示:随着冻融次数的增加,相同掺量下强度由大到小依次为CL改良土>SFL改良土>SL改良土;导热系数由大到小依次为SFL改良土>CL改良土>SL改良土;SFL改良土pH值最小且导电性能最好。【结论】结果表明:未经冻融循环的黄土试样掺入木质素后均能有效提高黄土强度和隔热能力并降低pH值,SFL改良土均展现出显著的优势,SFL自身具备的C=O双键使固化土表现出低pH值和高导电性,其隔热性能得益于石英的高含量。在冻融循环作用下,CL和SFL改良土通过促进土颗粒间的钙质和镁质胶结形成,有效增强土体的抗冻性和结构稳定性,降低冻胀现象对土体力学性能的负面影响。此外,考虑到SFL显著的性能提升与经济性,优先选择SFL作为冻土地区黄土改良的材料,研究成果可为中国西北地区的黄土改良工作提供一定的理论依据和科学参考。
[Objective]Focusing on loess from the Xining region of Qinghai,the mechanical properties and micro-mechanisms of lignin-modified loess under freeze-thaw cycles are investigated.[Methods]Freeze-thaw cycle tests are conducted on lignin-modified soil under closed system conditions.Basic physical property tests,unconfined compressive strength tests,and thermal tests are performed to comprehensively evaluate the reinforcement effects of calcium lignosulfonate(CL),sodium lignosulfonate(SL),and unsulfonated lignin(SFL)on loess.Scanning electron microscopy and X-ray diffraction are used to analyze the soil structure and composition.[Results]With the increase in freeze-thaw cycles,the strength of the soils at the same dosage decreases in the following order:CL-modified soil>SFL-modified soil>SL-modified soil.The thermal conductivity decreases in the order of SFL-modified soil>CL-modified soil>SL-modified soil.SFL-modified soil exhibits the lowest pH value and the best conductivity.[Conclusion]The result indicate that the addition of lignin effectively enhances the strength and thermal insulation capacity of loess while reducing its pH value.SFL-modified soil demonstrates significant advantages,as the C=O double bonds present in SFL contribute to lower pH values and higher conductivity in the stabilized soil.The thermal insulation performance benefits from the high quartz content.Under freeze-thaw cycles,both CL and SFL-modified soils enhance frost resistance and structural stability by promoting the formation of calcium and magnesium cementation between soil particles,thereby mitigating the negative impacts of frost heave on the mechanical properties of the soil.Furthermore,considering the significant performance improvements and economic benefits of SFL,it is prioritized as the material for loess improvement in frozen soil regions.The research findings provide a theoretical basis and scientific reference for loess improvement efforts in Northwest China.
作者
赵皓琪
张吾渝
刘昊阳
董超凡
ZHAO Haoqi;ZHANG Wuyu;LIU Haoyang;DONG Chaofan(College of Civil Engineering and Water Resources,Qinghai University,Xining 810016,Qinghai,China;Qinghai Provincal Key Laboratory of Energy-saving Building Materials and Engineering Safety,Xining 810016,Qinghai,China)
出处
《水利水电技术(中英文)》
北大核心
2025年第2期232-245,共14页
Water Resources and Hydropower Engineering
基金
青海省科技合作专项(2023-HZ-806)
国家自然科学基金项目(52168054,52468054)
国家留学基金委项目(202308630007)。
关键词
冻融循环
木质素
改良黄土
力学性能
PH值
微观机理
影响因素
freeze-thaw cycle
lignin
improving loess
mechanical properties
pH value
microscopic mechanism
infuencing factors
