兰州市非饱和黄土水土关系与力学性质变化规律

WATER-SOIL RELATIONSHIP AND MECHANICAL PROPERTIES OF UNSATURATED LOESS IN LANZHOU CITY

灌溉和降雨是兰州南北两山绿化区黄土斜坡失稳的最主要诱发因素。灌溉或降雨作用下,黄土斜坡失稳的本质是水与非饱和黄土相互作用后黄土力学性质改变的结果。因此,研究非饱和黄土中水土关系及力学性质变化规律,不仅为定量评价选取参数提供依据,而且是深入分析黄土斜坡变形破坏机理的基础。本次研究在现场调查基础上,以在城关区青白石、桃树坪、九州3处黄土斜坡上采集的132组原状黄土,以及在皋兰山Ⅲ-2滑坡上采集的16组滑体和滑带扰动样的室内试验结果为基础,分析非饱和黄土水土相互作用规律及水土关系特征。试验结果显示抗剪强度及其参数变化随含水率(饱和度)不断变化是水土作用的直接结果,降雨或灌溉或其他地表水体入渗后黄土含水量(饱和度)变化是导致黄土抗剪强度变化的最主要因素。

Irrigation and rainfall are the most important factors for the instability of the loess slope in the green area of the north and south mountains of Lanzhou.Under irrigation or rainfall,the essence of the destabilization of the loess slope is the result of the change of the mechanical properties of the loess after the interaction of water with unsaturated loess.Therefore,the study of the relationship between water and soil and the change of mechanical properties in unsaturated loess not only provides a basis for quantitative evaluation and selection of parameters,but also is the basis for in-depth analysis of the deformation and failure mechanism of loess slope.Based on the on-site investigation,the study was mainly based on the indoor test results of 132 groups of pristine loess collected on the three loess slopes of Qingbaishi,Taoshuping and Kyushu in Chengguan District,and 16 groups of slides and slip belt disturbance samples collected on the III.-2 landslide of Gaolan Mountain,and the water-soil interaction law and water-soil relationship characteristics of unsaturated loess were analyzed.The experimental results show that the continuous change of shear strength and its parameters with the moisture content(saturation)is the direct result of soil and water,and the change of loess water content(saturation)after rainfall or irrigation or other surface water infiltration is the most important factor leading to the change of shear strength of loess.