Comparative Field Tests on Straight-Sided and Belled Piers on Sloping Ground under Combined Uplift and Lateral Loads

Comparative field tests were carried out on two straight-sided piers and two belled piers under combined uplift and lateral loads on arid loess sloping ground with an inclination angle of 20 degrees. The pier-head uplift and lateral displacements, ground surface deformation, and soil pressures on the pier and bell were obtained. For both straight-sided and belled piers on sloping ground under combined uplift and lateral loads, the curves of the applied loads versus pier-head uplift displacement and pier-head lateral deflection exhibited an initial linear segment, a curvilinear transition, and a final linear region, and their capacities should be interpreted from the load test results. The pier-head uplift displacement and pier-head lateral deflection increased nearly at the same displacement increment, and the limit state of a pier on a slope under a combined uplift-lateral load may be primarily governed by the pier-head lateral deflection due to lateral soil failure. Belling may cause greater load-transfer depths and can effectively mobilize more soil to resist the combined uplift and lateral loads, and additional pier embedment in a slope can increase the uplift and lateral resistance to match the level-ground capacity for both straight-sided and belled piers. (C) 2018 American Society of Civil Engineers.