Abstract: As a special soil, the initial dry density of the phyllite residual soil can have a significant influence on the coefficient of the at-rest earth pressure. This paper focuses on the influence of the initial dry density on the coefficient of the at-rest earth pressure through the K₀ consolidation test and the Nuclear Magnetic Resonance (NMR) test. The research results show that the specimen with the smaller initial dry density has a larger pore structure and a greater compressibility. During the loading stage, with the influence of the cementation, the coefficient of at-rest earth pressure first decreases, then increases and then becomes stable. The increases with the increase of initial dry density. In the unloading stage, the at-rest earth pressure coefficient increases with the decrease of vertical stress, and the initial dry density has little influence on the at-rest earth pressure coefficient, which mainly depends on the stress history. Finally, the expression of the at-rest earth pressure coefficient considering the effect of the dry density during the loading and the unloading is analyzed.

Key words: The Coefficient of At-Rest Earth Pressure, The Initial Dry Density, K₀ Consolidation Apparatus, Nuclear Magnetic Resonance (NMR)