冻融作用下石灰改良土微观特性研究

Study on Microscopic Characteristic of Lime Improved Soil under Freezing and Thawing Action

为研究冻融作用下石灰改良土的微观机理,使用扫描电镜(SEM)对最优石灰掺量(6%)的石灰改良土及素土的微观结构进行分析,探讨不同冻融次数对石灰改良土微观结构的影响。试验研究结果表明:随着冻融次数的增加,素土土体结构破碎,土颗粒粒径变小,大孔隙数目减少,但总的孔隙数量增多,土颗粒间接触点数目增多;石灰改良土在冻融次数较少时土体破碎,碎屑物质较多,孔隙被碎屑填充,团聚体数量减少但体积增大;冻融次数较多时,土体孔隙数量减少,碎屑与胶结物质结合充分形成大团聚体,土体多为整体嵌合的集合体。因此,在土体中掺入适量石灰拌和均匀,且压实度满足设计要求的石灰改良土,可减轻路基的冻胀现象。

In order to study the microscopic mechanism of lime improved soil under freezing and thawing action, the scanning electron microscope （SEM） is adopted for analyzing the microstructure of the lime improved soil with optimal lime dosage and plain soil to explore the influence of different frequency of freezing and thawing on the microstructure. The experimental results show that with the increase in the frequency of freezing and thawing, the particle of plain soil mass breaks, soil particle gets smaller, the macropores decreases, but the total pores increases, and contact points between soil particles increases. With the decrease in frequency of freezing and thawing, the particle of lime improved soil mass breaks, the detrital materials are more, the pores are filled with detrital materials, and the aggregates decreases in number but the increases in volume. With the increasing frequency of freezing and thawing, the pores decreases, the detrital materials and cementing materials are fully blended to form macro aggregate, the soil is mostly aggregate formed by whole embedding.