基于SEM方法分析干湿和冻融循环对黄土微观结构的影响

为了研究高速公路边坡坡面表层剥落成因,在某高速公路K700+200处提取Q₃原状黄土进行室内试验,并考虑季节交替对黄土微观结构的影响.研究中采用扫描电镜(SEM)分别对0次、1次、5次、10次、20次干湿和冻融循环作用后的试样进行了SEM检测,对比并分析经过不同干湿循环和冻融循环次数后所得扫描电镜图像的变化规律.利用IPP图像处理软件,对土骨架和孔隙形态进行分析,获取经过不同次数的干湿循环和冻融循环作用后的面孔隙度、平均孔径、孔径分形维数的变化规律,定量分析不同干湿和冻融循环次数后土体微观结构的变化.分析结果表明:干湿循环和冻融循环对土的微观结构有较大影响,揭示了黄土边坡坡面表层剥落与干湿循环与冻融循环密切相关.

Effects of dry-wet and freeze-thaw cycles on microstructure of soil based on SEM

In order to investigate the cause of surface spalling of highway slope, we extracted Q₃ undisturbed loess at K700+200 of a highway. In the investigation, scanning electron microscope (SEM) was used to detect prepared samples after 0, 1, 5, 10 and 20 dry-wet cycles and freeze-thaw cycles respectively. Changes of SEM images after different dry-wet cycles and freeze-thaw cycles were compared and analyzed quantitatively. Soil skeleton as well as pore morphology are analyzed either by IPP image processing software in our research. Change rules of surface porosity, average pore diameter and pore size fractal dimension after different times of dry-wet cycle and freeze-thaw cycle are obtained therefore, and variations of soil microstructure after different dry-wet cycles and freeze-thaw cycles are quantitatively analyzed. Results coming from our investigations indicate that:Both dry-wet cycle and freeze-thaw cycle have great influence on soil microstructure. It is revealed further that the surface spalling of loess slope is closely related to dry-wet cycle and freeze-thaw cycle.