Regression models for validating cyclic triaxial test results men vs women dating
Coarse grained soils, which are generally the main construction materials of subgrade layer in railway system, usually present two types of deformation behavior when subjected to repeated traffic-type dynamic load: (a) resilient or recoverable deformation, which is related to the load-carrying ability of track structure, reflects stiffness properties of the material and (b) residual or irreversible deformation, which contributes to most of the subgrade settlement, determines long-term performance of railway line [1–4].
Although small compared to the resilient deformation, the residual deformation accumulates in each load cycle and may eventually reach a significantly large value that causes subgrade failure.
However, several researchers  have investigated and questioned the approach of predicting the permanent deformation of coarse grained soils under repeated loading based on monotonic failure stress, since unreasonable results were obtained for describing their experimental data.
They argued that the failure of specimen under monotonic loading presented as sudden collapse, but it was a gradual process when subjected to cyclic loading, so the structural response of the materials may not be the same in these two kinds of tests.
A simplified mechanistic empirical prediction model was proposed, which predicted the permanent deformation as product of four independent functions about cyclic stress amplitude, initial mean stress, initial stress ratio, and number of load cycles.
Afterwards, several research workers also attempted to correlate the results under repeated loading with the failure deviator stress from monotonic tests [13–15].