Abstract: Dispersive soil has the characteristic of dispersing and losing when encountering water. Buildings located in dispersive soil often suffer from seepage deformation at the interface under the coupling effect of soil-water-building, which often leads to dangerous situations in water conservancy projects. Using different artificially dispersive soil, and conducting dispersivity and impermeability tests. Considering the separation and void from the soil and building caused by uneven settlement, vibration and other factors,. Crack erosion tests were conducted on non dispersive soil and dispersive soil in the void area on the upper and lower sides of the pipeline. The results show that: (1) With the increase of sodium carbonate content, the soil samples gradually transitions from non-dispersibility to dispersibility. The critical hydraulic gradient decreased from 120.0 to 12.9 and 14.7, and the impermeability decreases significantly. (2) The cracks (without buildings) of dispersive soil and non-dispersive soil can be gradually healed under the protection of filter, and the crack section can bear a slope drop greater than 59.0 and 51.2 respectively at the end of the test, the anti permeability performance is significantly improved. (3) Under the same dry density, compared with non-dispersive soil, cracks in dispersive soil heal faster and can quickly fill and block the seepage channel under conditions of low-speed flowing water. (4) When the cracks are located in the upper part of the building, non-dispersive soil and dispersive soil can bear hydraulic gradients greater than 87.4 and 63.1, respectively, they can gradually heal under the protection of the filter and have certain impermeability properties; When the crack is located at the bottom of the building, the crack section basically does not bear the hydraulic gradient. It is difficult to heal under the protection of the filter, and it is prone to piping of the filter under high water head.