Laboratory Investigation of Ground Surface Settlement Caused by Erosion around a Leaking Pipe

Abstract

Ground subsidence may occur around deteriorated sewer pipes because of groundwater and soil infiltration into the pipes. Since field measurements are difficult to perform, it is important to use laboratory models to examine the effect of groundwater infiltration into perforated sewer systems. In the present research, a series of laboratory experiments were conducted in order to explore the impact of groundwater intrusion into a leaky sewer pipeline on ground deformation. In addition, the water and soil flow rates through the defective pipe were studied. For this purpose, a cracked pipe was tested in a sandbox model for different round opening sizes, water table depths, soil particle sizes, and hole positions along the pipe. It was found that hole size and location along the pipe, groundwater table height, and soil type had significant effects on the maximum depth of the depression hole and its width. Protecting pipelines exposed to subsidence in the field is very important. In order to predict the dimensions of depression holes around actual defective pipes, empirical formulas were developed based on dimensional analysis theory to compute the maximum depths and widths of depression holes. Then, preventive measures can be implemented to protect such pipes.