Experimental and numerical investigation on internal erosion induced by infiltration of defective buried pipe

Abstract

Soil erosion induced by infiltration of a buried defective pipe is closely related to leaking locations, whereas it has received inadequate attention in literature. In this paper, the distinct effects of various leaking locations on internal erosion are investigated extensively using both experimental tests and numerical simulations. First, a series of experimental model tests are carried out to characterize the evolution of ground collapses due to pipe leaking at different defect locations and to quantify the related soil–water loss (SWL). The experimental results indicate that the defect location has a significant effect on the SWL rate and ground collapse. When the leaking location is changed from the pipe crown to its invert, both the soil- and water-loss rates accelerate dramatically, followed by a more severe ground collapse. Then, a validated two-dimensional (2D) finite-difference method and discrete-element method (FDM-DEM) coupling model is established to explore the distributions of earth pressure (EP), water pressure (WP) and water-earth pressure (WEP) against the pipe and to disclose the influence mechanism of different leaking locations. It is found that EP and WEP in the proximity of the defect reduce significantly after pipe leaking, while EP away from the defect increases due to seepage force and soil arching effect. In addition, the distribution of EP against the defective pipe during internal erosion can be divided into three typical zones: fluctuation, soil arching and stable zones. The findings of this study will be helpful for researchers and practitioners to understand the internal erosion of strata triggered by infiltration of defective buried pipeline.