关键词: 黄土, 动剪切模量, 动剪应变, 动力压缩, 动剪应变累积模型

Abstract: With SDT-20 dynamic triaxial apparatus, the dynamic deformation properties of both intact and remolded loess are explored. The effects of different test parameters on the dynamic shear modulus and the accumulation of dynamic shear strain are qualitatively analyzed. In the prerequisite of small strain and taking no account of radial strain during loading, the void ratio of sample is derived according to axial dynamic strain, and the dynamic compression behavior of loess samples is analyzed with e-σ_d curves. Different from those under static loading, the characteristics of compression of loess are not revealed under dynamic loading, and the structure of intact loess is not obviously reflected as both intact and remolded loess experience a similar deformation process under dynamic loading. A turning point exists in e-σ_d curve of intact loess as well as that of remolded loess, which implies a critical dynamic stress for both intact and remolded loess. When dynamic stress is less than critical dynamic stress, the dynamic deformation of loess develops slowly; but when dynamic stress is greater than critical stress, the dynamic deformation increases dramatically and loess samples are destroyed quickly. In addition, a hyperbolic model is established to modeling the accumulation characteristics of dynamic strain of loess, and the model parameters are calculated with differential evolution method. By comparing the estimation of hyperbolic model with experimental data, we conclude that the proposed hyperbolic model could well describe the deformation properties of loess under dynamic loading.

Key words: loess, dynamic shear modulus, dynamic shear strain, dynamic compression, model for dynamic strain accumulation