Experimental Study on Uplift Mechanisms of Pipes Buried in Sloping Medium Dense Sand

Abstract

Experiments are conducted to study the uplift behavior of buried pipes in medium dense sand with ground slopings of 0°, 10°, 20°, and varying burial depths. Test results show that the peak uplift resistance reduces with the increasing sloping, and up to 10% reduction is observed for 20° sloping. The displacement of pipe where the peak is mobilized, δp, also reduces for 20° sloping. The uplift resistance experiences a quicker reduction after reaching the peak due to the ground sloping. The stress level increases on the uphill side and decreases on the downhill side, resulting in lower and higher dilatancy, respectively. Consequently, the angle of slip plane to the vertical direction become smaller on the uphill side and larger on the downhill side. The slip plane extends to the ground and a complete slip mechanism develops at a pipe displacement of 2δp. The postpeak softening behavior of uplift resistance oscillates at an amplitude increasing with the burial depth and decreasing with the sloping, due to the arching effect as soil moving around the pipe periphery.