The results of the model tests taken by a new developed seepage-consolidation apparatus with high pressure are briefly introduced in this paper. According to the data, the main characteristics of the compaction by pumping and dilation by recharging of the soil skeletons are analysed in detail. The function expressions of stress-strain relationship of soils with linear viscoelasticity, which is applied to explain the mechanism of the compaction and dilation of the soil skeletons of aquifer(s), are determined.