Simulation of soil fluidization around a pressurized leaking pipe using the material point method

Underground buried pipes are extensively used in water and sewer networks to meet different domestic and agricultural needs. Underground water networks may suffer from leakage problems through cracks or holes. Pipe leakage can lead to economic, environmental, health, and safety consequences. Leakage from pipelines can induce soil fluidization due to the increase of pore water pressure in the region of the leak. The soil fluidization reduces the bearing capacity of the supporting ground, ultimately leading to the collapse of the ground and the buried utilities. In this study, the soil fluidization mechanism due to pressurized pipe leakage is numerically modeled with the Material Point Method (MPM). MPM represents the continuum with a set of integration points, so-called material points (MPs) that move attached to the media, carrying all the material information. Two MPM two-phase approaches are used to understand the soil-fluid interaction mechanisms associated with a leaking buried pressurized water pipe embedded in fully saturated sand. The single-point approach represents the saturated medium with one set of MPs; the double-point approach separately models the solid and the liquid phases using two sets of MPs. The capabilities of the two approaches to simulate the onset and evolution of soil fluidization are presented and discussed. Finally, the displacement field and failure mechanism around the leaking pipe are analyzed in terms of the soil porosity.