Sand liquefaction caused by modern strong earthquakes is a very common phenomenon. Such as: 1966 Xingtai earthquake; 1975 Yingkou-Haicheng earthquake; 1976 Tangshan earthquake caused large-scale liquefaction of underground sand. Especially1July 28th, 976, two disastrous strong earthquakes occurred in Tangshan, Hebei province. A few minutes after the earthquake, sand liquefied in a large area, and water began to spray sand, which lasted for several hours, causing the surface to crack and sink, and finally the buildings collapsed in pieces. Liquefaction mechanism of sand: Saturated loose sand is a composite system composed of sand and water. Sand maintains its stability and bears pressure through the friction between particles. The mechanical property of water outburst is that the volume is incompressible and can bear near the pole.