Abstract: Serious piping will lead to instability of engineering. Based on the hydraulic condition of soil piping, the approach degree of critical hydraulic gradient is proposed to quantitatively analyze the risk of soil piping, which can distribute the piping risk area and put forward corresponding prevention suggestions. Taking a ship lock foundation pit with two piping accidents during construction as an engineering example, FLAC3D software is used to construct a three-dimensional numerical model, FISH language programming is used to analyze the evolution law of the hydraulic gradient and the approach degree of critical hydraulic gradient distribution with piping and foundation pit anti-seepage reinforcement during construction, and then the water inflow mechanism of the foundation pit is explored. The results show that when piping occurs in the foundation pit, both the hydraulic gradient and the approach degree of the critical hydraulic gradient of the soil at the location where piping occurs indicate that piping occurs there, in addition, the approach degree of the critical hydraulic gradient can divide other piping risk areas in the whole site except the piping location; the anti-seepage reinforcement suggestions based on the distribution of piping risk areas can effectively reduce the risk of piping in the soil at the bottom of the pit. The proposed approach degree of critical hydraulic gradient provides a new quantitative method of piping risk assessment for the prediction and prevention of piping in engineering.
Keywords: piping; hydraulic gradient; approach degree of critical hydraulic gradient; anti-seepage reinforcement; FLAC3D software; FISH language