Study on mesoscopic mechanism of water inrush in foundation pit based on discrete element method

With the development of urbanization, a large number of foundation pits have been built. Water inrush is one of the most important causes of foundation pit accidents, and it is of great significance to understand the process and mechanism of water inrush. A laboratory small-scale water inrush test at foundation pit base was established by using discrete element method and numerical simulation was conducted on the water inrush failure of aquitard. The water inrush process of Shanghai clay (5)(1) was divided into continuous deformation stage, equilibrium stage, and failure stage. The mechanism of water inrush failure was explained from a mesoscopic perspective, and the trend of the development and evolution of cracks was studied. The variation laws of monitoring variables such as porosity, coordination number, and the particle displacement of observation points were analyzed. The influences of vertical weak area in pit base and the thickness and properties of aquitard on water inrush were further discussed. The research work in this paper not only provides a new perspective for the analysis of water inrush failure in foundation pits, but also provides a reference for the simulation of fluid-solid coupling in other geotechnical engineering.