螺杆桩处理湿陷性黄土挤密效果分析与评价

螺杆桩因其特殊的成桩工艺和挤土效果,可有效改善桩间土的力学特性并消除黄土的湿陷性.为了研究螺杆桩消除黄土地基湿陷性的效果,对螺杆桩在不同桩心距条件下黄土的挤密效应进行较为系统的研究分析.试验结果表明:螺杆桩处理后的黄土复合地基,其桩与土之间有较好的挤密效果,黄土湿陷性明显消除;由于成桩工艺的特殊性,随着桩侧水平距离的增大干密度逐渐减小,且桩心距越小挤密效果越明显;湿陷系数随深度、饱和度增加均呈现减小趋势;建议用土的体积含水率代替质量含水率作为螺杆桩处理湿陷性黄土挤密效果评价的影响因素;在影响螺杆桩处理湿陷性黄土挤密效果的因素中,饱和度侧重于分析土压力的影响,液性指数主要考虑了土中空隙的影响.

Screw pile to deal with collapsible loess foundation experiment analysis and evaluation

Because of its special pile technology and compaction effect, screw pile can effectively improve the mechanical properties of soil between piles and eliminate the collapsible of loess. In order to study the effect of screw pile on eliminating the collapsibility of loess foundation, the compaction effect of screw pile on loess under the condition of different pile center distance is studied and analyzed systematically. Test results show that the loess composite foundation treated with screw pile has a better compaction effect between pile and soil, and the collapsibility of loess is eliminated obviously. The dry density decreases with increase of the horizontal distance of the pile side due to particularity of the pile forming technology, and further the smaller the pile core distance is, the more obvious the compaction effect is. The collapsible coefficient decreases with the increase of depth and saturation. It is suggested therefore that the volumetric water content of soil instead of mass water content should be used as the influence factor of screw pile in the evaluation of collapsible loess compaction effect. Among those factors affecting the compaction effect of the screw pile in collapsible loess, the saturation focuses on the influence of soil pressure, and the liquid index mainly considers the influence of voids in the soil.