以去掉扩头的原状土直柱基础为研究对象，选取750 kV兰—天—宝输电线路甘谷变电站厂址为试验场地，开展了黄土地基中直柱掏挖基础浸水静载荷试验。通过对基础施加上拔+水平组合荷载和下压+水平组合荷载，得出了浸水期间基顶位移沉降量，并且通过分析基础Q－S曲线得出浸水前后基础的上拔、下压极限承载力。在此基础上，对相同设计条件下的直柱基础与扩底基础进行了经济分析，进一步阐述了该类基础的安全性和经济性。该研究成果可为750 kV兰—天—宝输电线路优化设计和安全施工提供理论指导依据。

Taking column foundation with undisturbed soil on loess as a research object, the site full-size water immersion static load test was carried out at Gangu substation of 750 kV Lanzhou-Tianshui-Baoji power transmission line project. The load-displacement of top foundation with water immersion was measured under uplift load combined with horizontal load and compressive load combined with horizontal load on the basis. Through the analysis on Q－S curves of test foundation, the ultimate uplift, and compressive bearing capacity of foundation were obtained. On this basis, the economic comparison between column foundation and spread foundation under the same design condition was carried out to further discuss the safety and economy of this kind of foundation. The research results could provide a theoretical basis for the optimization design and safety construction of 750 kV Lanzhou-Tianshui-Baoji power transmission line.