庆阳地区超高层巨厚层黄土地基工程地质特征

为了更深层次地了解黄土的地质特征，以庆阳地区某超高层巨厚层黄土地基为研究对象，对陇东黄土的物理和力学性能进行了深入探究。主要通过原位试验与室内试验，从地层结构、分布深度、液限、塑限、塑性指数、孔隙比、湿陷变形、剪切波速、地基土承载力、抗剪强度等方面对该地区黄土的工程性能进行了综合分析与评价，结果表明：5.0 m以内的马兰黄土湿陷性较强烈，黏聚力小，压缩性大；随着黄土厚度逐渐增大，离石黄土及午城黄土黏聚力增大，压缩性减小，呈轻微-中等湿陷性；受压超过400 kPa的马兰黄土、受压大于600 kPa的离石黄土及受压大于200 kPa的午城黄土均无湿陷性；15.0 m以内土体最大干密度为1.67~1.76 g/cm³，最优含水率为16.6%~17.7%；含水率高值相对集中在地下水位62.0 m以下、饱和度90.0%以上地区。

Engineering Geological Characteristics of Super High Rise and Thick Loess Foundation in Qingyang Area

In order to deeply understand the geological features of loess, the super high-rise and thick loess foundation was selected as the study object in Qingyang, to investigate the physical and mechanical properties of Longdong loess. Mainly through in-situ and indoor experiments, all sides of loess engineering performance were comprehensively analyzed and evaluated, including the under structure, depth of distribution, liquid limit, plastic limit, index of plasticity, void ratio, collapsible deformation, shear wave velocity, bearing capacity of foundation, shear strength, and so on. The results showed that:Malan loess within 5.0 m had strong collapsibility, small cohesive force, and large compressibility; with the gradual increase of loess thickness, the cohesive force of Lishi loess and Wucheng loess increased, while the compressibility decreased, showing a slight to moderate collapsibility;when the pressure of Malan loess exceeded 400 kPa, the pressure of Lishi loess was greater than 600 kPa, and that of Wucheng loess was greater than 200 kPa, with no collapsibility; the maximum dry density was 1.67-1.76 g/cm³, and the optimal water content was between 16.6% and 17.7% within 15.0 m; the high water content was relatively concentrated in the region below 62.0 m of groundwater level and above 90.0% of saturation.