Interaction Mechanism of the Frost Heaving of the Filler and Skeleton Particles in a Micro-Frost-Heaving Filling Material

Abstract

To address the adverse effects of the frost heaving of subgrades in regions with seasonal frozen soil on the smoothness of high-speed railway tracks, the effects of several factors—including filler, water content and external loading—on a micro-frost-heaving (MFH) filling material were studied through laboratory experiments and theoretical analysis. In addition, the interaction mechanism between the filler and skeleton particles during the frost heaving process was analyzed. The results show the following: The MFH filling material was composed of a coarse-grained skeleton, a filler between skeleton particles and the remaining unfilled voids. When the filling ratio of the filler was 0.25, the filling material underwent initial macroscopic frost heaving. An overlying load could inhibit the filling material from frost heaving. During the frost heaving process, the volume of coarse skeleton particles with high stiffness remained almost unchanged, whereas the filler expanded in volume and thus filled the remaining voids between skeleton particles and lifted the skeleton particles, resulting in macroscopic frost heaving of the filling material. When their ratio was relatively high, the remaining voids between skeleton particles had a strong absorptivity and weakened the capacity of the filler to lift the skeleton particles. The filler raised the skeleton particles, resulting in an increase in the gaps between them, which in turn facilitated the filling action of the filler. When the skeleton structure was stable, the filling action of the filler was more pronounced. The frost heaving of an MFH filling material is in fact a dynamic equilibrium process between the filling and lifting actions of the filler.