Experiment and numerical simulation on seepage failure of sand caused by leakage of underground water pipe

Abstract

Underground water pipe leakage accident is a serious threat to the city road and people's life safety, the internal mechanism is necessary to carry out related study. In this paper, numerical simulation technology and model test device was used for researching on the effect of different factors on the seepage failure of sand. The research shows that the evolutionary process of sand seepage failure induced by underground water pipe leakage can be divided into three stages: unfluidized stage stable cavity stage and fluidized stage. At the initial stage, the pressure distribution at different height reaches a peak with the increment of water pressure and flow rate. When the water pressure and flow rate is beyond the peak, cavity would occur at leakage hole. Under the action of seepage force, the cavity would dissipate at the surface of soil, and the distribution of fluidized bed pressure would maintain a stable state. Moreover, the smaller the leakage diameter, the greater the critical water pressure is. In a numerical test of a wedge angle of 62 degrees, F (upward drag force) is equal to the W (weight of wedge), which indicates the cavity reaches a force balance. The wedge with an angle of 62 degrees is significant to the sample model used in numerical simulation.