Wetting induced volume change behavior of compacted expansive soil with different initial state

In traditional unsaturated constitutive models, the wetting-induced volume change usually described by suction modulus (H) in compressibility form or matric Suction Decrease (SD) curves in BExM. In practice the unsaturated soils are not subjected to matric suction decreasing step by step as done in laboratory, and the more common conditions were that the soils subjected rainfall and other forms of precipitation are humidified to totally saturated and induced swelling or collapse which is dependent on the current stress and matric suction state. In this paper, a series of compacted expansive soil specimens with different initial void ratio and initial matric suction were soaked in oedometer under different vertical load, and the vertical deformations of the specimens were measured. A simple model was established by which expansive soils can avoid both swelling and collapse by controlling its initial void ratio and matric suction. Moreover, in e-lg(s)-lg( sigma(v)) space there is a critical surface on which any point represents a certain pressure and matric suction state of expansive soil. In this state, wetting would induce no volume change.