延安新区马兰、离石黄土饱和渗透特性的试验研究

饱和渗透系数是重要的水文地质参数，由于沉积环境的不同，不同地层黄土的饱和渗透性存在明显差异，研究黄土在天然状态下与室内不同压实情况下的渗透特性对揭示挖填混合区域的地下水流场有重要的理论意义。本次研究以延安新区的马兰黄土及上离石黄土为研究对象，通过室内常规渗透试验，测定原状样及不同干密度重塑样的饱和渗透系数，并进行对比研究。结果表明：原状马兰黄土的密实度相对略低，其饱和渗透系数高于原状离石黄土，约为原状离石黄土的2～4倍。重塑马兰黄土与重塑离石黄土的饱和渗透系数差异不大。在击实作用下，重塑黄土的饱和渗透系数明显降低，约为原状黄土的0.38倍。由于生物孔洞等的存在，原状马兰黄土的饱和渗透系数与孔隙度或干密度无显著的单调关系。而原状离石黄土及重塑黄土的饱和渗透系数随孔隙度的增大而增大，随干密度的增大而减小，且重塑黄土的饱和渗透系数与孔隙度和干密度呈半对数关系。

EXPERIMENTAL STUDY OF PERMEABILITY OF MALAN AND LISHI LOESS IN YAN'AN NEW AREA

For different sedimentary environments, saturated hydraulic conductivity, which is an important hydrogeologic parameter, are quite different in every formations. In some engineering projects, original formation is disturbed, and the groundwater flow may be changed because both high embankment and excavation comprise a new formation. In this way, it is important to conduct the research on the saturated hydraulic conductivity of undisturbed loess and remolded loess. In this study, the samples such as Malan loess and Lishi loess in upper layer were collected from Yan'an new area, and the saturated hydraulic conductivity of both undisturbed loess and remolded loess were examined by conducting indoor routine permeability experiment. The comparison results show that the compactness of undisturbed Malan loess is lower than that of undisturbed Lishi loess, and the saturated hydraulic conductivity of undisturbed Malan loess is about 2~4 times higher than that of Lishi loess. However, there are no significant differences between the saturated hydraulic conductivity of remolded Malan loess and that of remolded Lishi loess, but the saturated hydraulic conductivity of loess significantly decreases by three fifths when the original structures are disturbed. Besides, for the biology holes existing in undisturbed Malan loess, the relationship between saturated hydraulic conductivity and dry density or porosity is not monotony. Whereas, a good linear relation exists between log permeability and porosity or dry density for undisturbed Lishi loess and remolded loess.