Testing and Evaluation on Dynamic Response of a New Modified Soil Subgrade under Freeze-Thaw Cycles

Abstract

Abstract Dynamic response analysis is an effective method of evaluating the strength, deformation, and stability of subgrade under repeated vehicle traffic loads. It is usually premised on the results of a field test, which not only requires a lot of manpower and money but also can be easily affected by extraneous factors. In this study, a laboratory test was conducted in order to examine the dynamic response of a new type subgrade: silty clay (SC) modified by fly ash and crumb rubber (RFS). A novel tester was adopted in order to simulate and impulse traffic loads with different vehicle speeds/weights on subgrade materials. In addition, the dynamic stress and acceleration responses of RFS and SC were analyzed under varying speeds and axle loads under 0–5 freeze-thaw (F-T) cycles. Thereafter, scanning electron microscope tests were conducted to bring about clarity regarding the effect on the internal structural changes of two test soils in order to elaborate on the reasons for these dynamic response changes. According to the findings of these tests, the dynamic stability of SC is better than the RFS before F-T cycles. However, the RFS provides better resistance to F-T dynamic stability as the F-T cycle goes on. In particular, the RFS is more suitable for subgrade filling in seasonally frozen regions. Against this backdrop, the current article proposes a convenient method to evaluate the dynamic response of subgrade in laboratory, besides providing a reference for the dynamic characteristics of RFS.