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.