Experimental investigation on Malaysian kaolin under monotonic and cyclic loading: inspection of undrained Miner's rule and drained cyclic preloading

The results of an experimental investigation on Malaysian kaolin under monotonic and cyclic loading are presented. In the tests, a wide range of initial conditions was varied in order to investigate their influence on the mechanical behavior of the kaolin. The response under monotonic loading was analyzed by means of undrained monotonic triaxial tests with different initial mean effective pressures and overconsolidation ratios. The experimental plan under cyclic loading includes an oedometer test with multiple unloading-reloading cycles and twenty-one undrained cyclic triaxial tests with either isotropic or anisotropic consolidation. In the latter tests, the influence of the initial stress ratio, deviatoric stress amplitude, drained cyclic preloading and sequence of packages of cycles with different deviatoric stress amplitudes has been investigated. The experimental results suggest that the variation of the aforementioned test conditions leads to remarkable changes in the accumulation rates of pore water pressure and strains. In addition, it was found that the so-called Miner's rule (independence of accumulated strains on loading sequence) is not valid under undrained cyclic conditions. A modified Stewart's approach was proposed for the estimation of the accumulated pore water pressure and strains on undrained cyclic tests with packages of cycles with different deviatoric stress amplitudes, demonstrating that constitutive models developed using single-magnitude loading packages can be used in simulations of problems with variable cyclic loading magnitude.

Automated summary

This study presents the results of experimental investigation on Malaysian kaolin under monotonic and cyclic loading. It was found that the mechanical behavior of the kaolin is significantly influenced by the variation of initial conditions. The experimental results also suggest that the Miner's rule is not valid under undrained cyclic conditions. A modified method was proposed to estimate the accumulated pore water pressure and strains in undrained cyclic tests with different loading magnitudes.