Equivalent Modulus for Fine-Grained Subgrade Soil

Previous studies on repeated-load California bearing ratio (RLCBR) tests have described its application to estimate the equivalent modulus of soil as stiffness modulus under repeated load. However, the effects of physical state and stress state on the modulus have not been discussed in detail. The present study was carried out, therefore, to evaluate the influence of physical state and stress state on the equivalent modulus of CBR samples using RLCBR tests. Samples were prepared using fine-grained soil to carry out the RLCBR tests under various physical and stress states. A deformation model was developed to estimate the equivalent modulus of the CBR sample from the results of RLCBR testing. Finally, the equivalent modulus of the soil was estimated using a finite-element model. The values of equivalent modulus were found to be comparable to those of resilient modulus obtained from correlation, which indicates that the method followed in the present study is useful to estimate the stiffness modulus of soil with an acceptable accuracy.