Compaction behavior of compacted Maryland expansive soil considering micro-structure effect

In order to study the evolution of stress status of expansive clay, a series of compaction tests for ML clay had been carried out. The samples with different initial water contents were compacted via a home-made one-dimensional compaction apparatus. The evolutions of suction and deformation of samples were analyzed during the compaction process. It shows that compression index(Cc) is significantly affected by initial water content. The value of Cc increases with initial water content if the initial water content is smaller than 21.4%, otherwise it keeps almost constant. The initial water content has little effect on the unloading-reloading index(C r). Due to the "mechanical wetting" effect, the matric suction gradually decreases during compaction. During the unloading stage, the matric suction increases significantly. For the sample with same initial water content, the increment of matric suction due to unloading effect increases with the degree of saturation. Based on the post-compaction suction, the compaction plane could be divided into parts: the post-compaction suction is not affected by the degree of saturation of samples, and the post-compaction suction increases with degree of saturation. It also clearly shows that soil water retention curve of sample with constant volume is strongly affected by the void ratio. Based on suction, the degree of saturation, average effective stress, modified suction and void ratio, models for soil water retention curve and compaction curve have been established. The predict of suction and volume evolution during the compaction has been carried out. © 2021, Science Press. All right reserved.