不同地区原状黄土土水特征曲线试验研究及其在边坡稳定性评价中的应用

我国黄土具有明显的区域分布特征,从空间平面上把握其非饱和特性分布规律具有一定的现实意义。以Ⅰ带—兴县、Ⅱ带—富县和Ⅲ带—西安原状黄土为研究对象,测定了黄土不同含水率条件对应的基质吸力,对试验数据拟合得到土水特征曲线变化规律,并利用干燥过程的土水特征曲线对一维无限边坡稳定性进行研究。结果表明:兴县、富县、西安原状黄土土水特征曲线在地理空间分布上具有一定的规律性;沿兴县—富县—西安,黄土土样进气值逐渐减小,降湿率呈减小趋势,残余含水率呈增加趋势; Van Genuchten模型对黄土原状土样拟合效果比Gardner方程更好,简化的Van Genu-chten模型对各地区黄土均能较好地拟合;随着深度的增加,边坡稳定性系数逐渐降低,同时随着饱和度的降低,边坡稳定性系数逐渐增加;同时兴县黄土边坡较为稳定,主要是兴县黄土的基质吸力项对抗滑力的贡献要明显大于富县和西安黄土。

Experimental study on soil-water characteristic curve of undisturbed loess in different regions and its application to slope stability evaluation

As loess in China has obvious regional distribution characteristics，it has certain practical significance to grasp the distribution law of its unsaturated characteristics from spatial plane. By taking the original belt loesses of I belt-Xingxian，II belt-Fuxian and III belt-Xi'an as the study objects herein，the matrix suctions corresponding to different moisture content conditions of the loesses are measured，and then the variation law of the soil-water characteristic curve is obtained through fitting the relevant experimental data，while the stability of the one-dimensional infinite slope is studied with the soil-water characteristic curve of the drying process. The result shows that the soil-water characteristic curves of the undisturbed loesses in the regions of Xingxian，Fuxian and Xi'an have certain regularities in the geospatial distribution. The airentryvalues of the loess samples taken from the regions along Xingxian-Fuxian-Xi'an are gradually decreased with the decreasing trend of moisture reduction rate and the increasing trend of residual water content. The fitting effect of the undisturbed loess samples from Van Genuchten model is better that that from Gardner equation，thus the loesses from all the regions can be better fitted by Van Genuchten model. Following with the increase of depth，the slope stability coefficient is gradually decreased，while it gradually increased along with the increase of saturation. Meanwhile，the loess slope in XingxianCounty is relatively stable; for which the reason is that the contribution from the matric suction of the loess in Xingxian County to the anti-sliding force is obviously greater than that from the loesses from Fuxian County and Xi'an.