Ultimate Uplift Capacity of Transmission Tower Foundation in Undisturbed Excavated Soil

Excavated transmission tower foundation in stiff soil is intensively recommended because it can basically keep soil undisturbed and thus adequately exert the strength of soil to resist the tension from transmission tower line. However, Chinese current code for design of this type of foundation exist certain problems. Therefore, this paper employed finite element method to simulate foundation uplift behavior in undisturbed soil and explained the difference among the results of two methods in code and FE analysis. Moreover, the effects of embedment depth, soil property, extended angle of foundation base on failure mode and ultimate uplift capacity are investigated by means of parametric analysis. It is concluded that shallow mode and deep mode occur for different embedment depth. Friction angle has significant effects on sliding surface, and cohesion slightly affects the shape of sliding surface. Base extended angle of 45 °corresponds to the largest sliding surface and ultimate uplift resistance by contrast with other angles.