Research on the Influence of Digged Foundation Size on Uplift Stability Based on the Orthogonal Test

In the current transmission lines, the digged foundation has been widely used in engineering because of its advantages in fully exerting the undisturbed soil’s large uplift capacity and improving the resistance to uplift and overturning load-bearing capacity. In this paper, four dimensions of the foundation, including main column diameter, main column height, expanded bottom width and expanded bottom height, are selected. Through orthogonal experiments, the value of each size is changed, the uplift force is calculated, the uplift stability margin is obtained, and the sensitivity of each size to the stability of the foundation is studied. The results show that for single-circuit linear towers, the degree of influence on the uplift stability of the digged foundation is in the order of main column diameter>main column height>expanded bottom width>expanded bottom height; while for double-circuit linear towers, the order of influence is expanded bottom width>main column diameter>main column height>expanded bottom height. The uplift stability of the foundation increases linearly with the increase of the main column diameter and expanded bottom width. For the double-circuit linear tower, due to the limitation of the foundation bearing capacity, the increase in the uplift resistance is small with the increase of the expanded bottom width. In the actual project, the foundation size should be selected reasonably to ensure the safety of construction.