Abstract: Indoor confined consolidation tests of compacted Q₂、Q₃ loess in Yan’an region are carried out in this research work. Factors to influence deformation characteristics of the compacted loess are discussed either. A best fitting model is established to characterize stress-strain relationship of the compacted loess under lateral conditions. On this basis, this paper analyzes the relationship between secant modulus and vertical compressive stress and the relationship between secant modulus and compactness under the condition of optimal water content, and puts forward a generally applicable constitutive model for the compacted loess. The results show that: After the consolidation of compacted Q₂ loess, the soil has high compactness, low gas content, low permeability and small additional deformation under applied load, so it is a good filling-material in the foundation. The Gunary model, with high fitting accuracy and good stability, is suitable for characterizing the stress-strain relationship of the compacted Q₂ and Q₃ loess under lateral conditions. The relationship between secant modulus and vertical compressive stress obtained from the transformation of Gunary model covers the linear relationship in the case of low pressure compactness and the nonlinear relationship in the case of high pressure compactness, which has better applicability.

Key words: confined compression, compacted loess, stress-strain relationship, consolidation, Gunary model, deformation characteristic, high-filled project