To scientifically explain the mechanism of piping disaster and reveal its formation, evolution process and burst law on the basis of considering the action of loam transition layer between the strong and weak permeable layers of dike foundation, the whole process of piping of a binary dike foundation structure from single bubble spring to piping group and finally resulting in collapse of dike foundation was completely simulated by indoor model test. The results show that the overlying soil layer uplifts upward under the jacking effect of seepage and produces horizontal channels between layers inside the dike foundation, leading to submerged sand boiling and eventually develops upward to the seepage failure of surface sand boiling. The piping development of binary dike foundation structure can be divided into six stages, including crack development, latent layer failure, overlay damage, upward development of piping channel, damage of dike foundation and dike break.The surface sand boiling is developed from the submerged sand boiling. The submerged sand boiling is caused by the damage of the soil structure induced by the seepage force due to the vertical slope in the soil layer greater than the floating bulk density of the upper soil. The critical vertical slope is between 0.9 and 1. The existence of loam layer accelerates the development of piping group in the free boundary area behind the dike, but it can delay the upstream of piping channel and protect the dike foundation.