不同埋深马兰黄土孔隙结构试验

本文采用"注胶法"制得用以观察分析和定量研究的黄土微观结构试样，借助扫描电子显微镜和数字化图像分析系统，观察并讨论黄土孔隙结构特征及其随黄土埋深增加的变化规律。结果表明，不同埋深马兰黄土依据孔隙率或孔隙面积率分类均属于疏松多孔性土。黄土孔隙连通性随埋深增加逐渐减弱；埋深由小到大，马兰黄土孔隙的主要结构特征由相对不稳定的大、中架空孔隙，过渡为相对稳定的微、小镶嵌孔隙，定量表现为大、中孔隙面积率之和随黄土埋深的增加减小约63.04%，而小孔隙面积率增加约40.57%，微孔隙面积率增加约22.47%。通过对孔隙形状分布的分析，上述不同类型孔隙面积率的增加或减少主要源于细长形和不规则形孔隙面积的改变。此外，不同埋深马兰黄土中细长孔隙的面积在微、小、中、大孔隙的面积中均占主导地位。就孔隙数量而言，马兰黄土中微、小、中、大孔隙的数量随深度增加依次急剧减少，此现象主要由4种孔隙中圆孔数量的显著差异引起，表明圆孔的孔径多偏小。

Experiment on Pore Structures of Malan Loess at Different Buried Depth

Loess samples were prepared using pore-filling method to observe and analyze their microstructures. The pore structures and the change with depth increase were analyzed by scanning electron microscope and digital image analysis system. The five samples belong to porous soil according to the void ratio or pore area ratio. The results indicate that the connectivity of loess pore decreased with depth increase gradually, the pore structure changed from unstable overhead macro pores or mesopores into stable small or micro mosaic pores,and quantitatively, the area of macro pores and mesopores decreased by 63.04%, while the area of small pores and micro pores increased by 40.57% and 22.47% respectively. By analyzing pore shapes, the area change of micro pores, small pores, mesopores and macro pores mentioned above was resulted from the area change of elongated or irregular pores. From the area point of view, in the micro pores, small pores, mesopores and macro pores, the elongated pores were dominant, and the number of all these four kinds of pores decreased in turn significantly. This is mainly determined by the number of round pores, indicating that the round pores are small.