Thermal Shrinkage and Cracking Behavior of Foamed Lightweight Soil under Temperature Cycling and Region Minimum Service Temperature Range: An Experimental and FDEM Study

Abstract Foamed lightweight soil (FLS) subgrades in cold regions are highly susceptible to temperature-induced shrinkage cracking, compromising long-term durability. This study investigates the coupled effects of silty clay content, temperature cycling, and service temperature range on FLS shrinkage behavior and crack evolution through laboratory tests and finite–discrete-element method (FDEM) simulations. Experimental results show nonlinear accumulation of shrinkage strain under cyclic thermal loading, with 20% silty clay significantly enhancing stability. Analysis of variance identifies silty clay content as the dominant factor over temperature cycling frequency. FDEM simulations reveal strain localization and crack initiation under heterogeneous temperature fields, with cracks evolving in three stages: initiation, rapid propagation, and stabilization. Lower minimum service temperatures play a dominant role in accelerating crack development and structural deterioration. Integrating experiments and simulations clarifies how key material and environmental factors govern FLS thermal shrinkage, providing a preliminary reference for crack-resistant design and long-term reliability assessment of FLS subgrades in cold regions.