摘要
抗冻性能是影响季节冻土区路基结构稳定性与服役寿命的关键因素。为系统研究粉煤灰路基材料在冻融环境下的抗冻性能,本文开展了不同龄期、压实度及循环次数条件下冻融循环试验与力学性能测试,分析其无侧限抗压强度、劈裂抗拉强度及微观结构演化规律;通过质量损失率与强度保持率等指标,量化评估材料在冻融作用下的劣化程度;结合XRD与SEM测试,揭示C-(A)-S-H等水化产物持续生成及其在孔隙填充、结构致密化与强度增强中的微观机制。结果表明:粉煤灰力学性能随龄期增长和压实度提高而显著增强,而冻融循环引发的结构破坏使强度逐步退化,呈现出“快速劣化—减缓衰退—性能趋稳”的演化特征。水化产物形成桥联结构提升了材料致密性与抗冻性能,宏观上反映为破坏模式由劈裂型向“X”型及剪切型逐步演化。同时,基于试验数据构建多元非线性回归模型可较为准确预测不同条件下粉煤灰的无侧限抗压强度。研究成果可为西北季节冻土区粉煤灰路基设计优化与性能评估提供理论依据与技术支撑。
Frost resistance is a key factor affecting the structural stability and service life of subgrades in seasonally frozen soil regions.To systematically investigate the frost resistance of fly ash-based subgrade materials under freeze-thaw conditions,this study conducted freeze-thaw cycle tests and mechanical performance evaluations under different curing ages,compaction degrees,and cycle numbers.The evolution patterns of unconfined compressive strength(UCS),splitting tensile strength,and microstructural characteristics were analyzed.Material degradation under freeze-thaw action was quantitatively assessed using indicators such as mass loss rate and strength retention rate.Microstructural evolution was further analyzed through X-ray diffraction(XRD)and scanning electron microscopy(SEM),revealing the continuous formation of C-(A)-S-H hydration products and their microstructural mechanisms in pore filling,structural densification,and strength enhancement.The results indicated that the mechanical properties of fly ash significantly improved with curing age and compaction degree,while freeze-thaw cycles induced structural damage leading to progressive strength degradation,characterized by three stages:rapid deterioration,gradual decline,and eventual stabilization.The formation of hydrationinduced bridging structures enhanced material compactness and frost resistance,which was macroscopically manifested in the progressive evolution of failure patterns from splitting to“X”-shaped and shear types.Furthermore,a multivariate nonlinear regression model was developed to accurately predict UCS under different conditions.These findings provide a theoretical basis and technical support for the design optimization and performance evaluation of fly ash-based subgrade materials in seasonally frozen soil regions of northwest China.
作者
顾士周
惠迎新
袁化强
张如江
闫升
陈伟
GU Shizhou;HUI Yingxin;YUAN Huaqiang;ZHANG Rujiang;YAN Sheng;CHEN Wei(School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China;Ningxia Communications Construction Co.,Ltd.,Yinchuan 750021,China;Xinjiang Communications Construction Group Co.,Ltd.,Urumqi 830000,China;Xinjiang Transportation Construction Planning,Survey and Design Co.,Ltd.,Urumqi 830000,China)
出处
《冰川冻土》
2025年第5期1358-1375,共18页
Journal of Glaciology and Geocryology
基金
宁夏回族自治区自然科学基金项目(2025AAC030528)
丝绸之路经济带创新驱动发展试验区、乌昌石国家自主创新示范区科技发展计划项目(2023LQ03002)
宁东能源化工基地本级重点支持领域科技项目(20250301NDKJ020)资助。
关键词
粉煤灰
抗冻性能
冻融循环
微观机理
季节冻土区
fly ash
frost resistance
freeze-thaw cycles
microstructural mechanism
seasonally frozen soil regions
