Evolution of axial cumulative strain and micro-pore structure characteristics of solidified mud under cyclic loading

Abstract

Embankments and foundation geotechnical structures are frequently subjected to long-term cyclic loading due to traffic during their service life. Excessive cumulative deformation can lead to pavement cracking and uneven settlement of the subgrade. This study conducts a series of dynamic triaxial tests to analyze the effects of the number of cycles (N), effective confining pressure (σ_c), and dynamic stress amplitude (σ_d) on the axial cumulative strain (ε_d) characteristics of solidified mud samples. Additionally, it investigates the evolution model of ε_d of solidified mud and establishes a predictive model for this strain. In conjunction with the NMR tests, this research further investigates the effects of σ_c and σ_d on the pore distribution of solidified mud after loading. Ultimately, the correlation between microscopic pore structure indicators and ε_d is elucidated. The results indicate that the ε_d behavior of solidified mud under cyclic loading exhibits characteristics of plastic shakedown. Furthermore, the exponential hyperbolic function model more accurately characterizes the relationship between ε_d of the samples and N. Before and after cyclic loading, the micropores of the samples accounted for over 95 % of the total pore volume, predominantly concentrated in the radius range of r < 0.3 μm. A correlation exists between the average pore size of the sample and ε_d, which is primarily influenced by σ_d and σ_c.