A Possible Test Method Proposed for Resilient Modulus (M_R) and Analysis of Correlation between Resilient Modulus and Shear Modulus of Track Subgrade Soil

Abstract

In general, under the repetitive dynamic load generated by rail cars running on the track, subgrade soil experiences changes of stress conditions such as deviatoric stress (σ d ) and bulk stress (θ). Due to the repetitive change of deviatoric stress (σ d ) with number of loadings, the resilient modulus (M R ) can be obtained by using the measured resilient strain (ε r ) after a sufficient number of loadings. At present, no plausible and unified test method has been proposed to obtain the resilient modulus of railway track subgrade soil. In this study, a possible test method for obtaining the resilient modulus (M R ) of railway track subgrade soil is proposed; this test, by utilizing repetitive triaxial compression testing, can consider all the important parameters, such as the confining stress, deviatoric stress, and number of loadings. By adapting and using the proposed test method to obtain M R , M R values for compacted track subgrade soil can be successfully determined using soil obtained in three field sites of railway track construction with changing water content range from OMC. In addition, shear modulus (G) ~ shear strain (γ) relation data were also obtained using a midsize RC test. A correlation analysis was performed using the obtained G and M R values while considering the strain levels and modes of strain direction.