Abstract:

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.