为了提高原状土掏挖基础的抗拔性能，通常在底部设置一定尺寸的扩大头。对于大荷载输电线路杆塔，为了满足扩大头处素混凝土的抗剪要求，扩大头通常设计得比较高大，不仅经济性差，而且在施工过程中存在安全隐患。针对上述工程问题，以去掉扩大头的原状土直柱基础为研究对象，选取兰州—天水—宝鸡750 kV输电线路沿线的2个试验场地，开展了上拔+水平组合工况的原状土直柱基础静载试验，分析了基础荷载-位移的变化规律及土体破坏模式，获得了各个试验基础的承载力值，并且推算出了侧摩阻力值。

In tradition, expanding head in certain size was set at the bottom of dredged foundation in undisturbed soil in order to increase the foundation’s uplift bearing capacity. For the transmission line tower with large load, uplift stability analysis was no longer a key factor for foundation design. However, expanding head was made huge to satisfy the shearing requirement of concrete, so that it was uneconomic and unsafe in the design process. In view of the above engineering problems, The column foundation without expanding head in undisturbed soil on loess was taken as a research object in this study, and two test sites along 750 kV Lanzhou-Tianshui-Baoji transmission line were selected to carry out the static load test of undisturbed soil column foundation under uplift combined with horizontal loads. This paper studied the variation of load-displacement and the failure mode of foundation soil, obtained the bearing capacity of each test foundation, and calculated the value of side friction.