Abstract: Concrete materials in most zones of real hydraulic structures are generally in an unsaturated state. When such hydraulic concrete is subjected to water in its service period, unsaturated water absorption occurs, resulting in an increase in its internal water content, so that it will experience moisture expansion deformation that affects the stress and strain state of the structure. In order to improve the accuracy of moisture diffusion coefficient and moisture expansion coefficient of unsaturated hydraulic concrete, this paper presents an inversion method for calculating these coefficients based on a combination of "measured moisture expansion strain - orthogonal design - neural network - numerical calculation". Its feasibility is demonstrated by combining with the laboratory wet expansion test data of unsaturated hydraulic concrete under typical ages. The results show that for the hydraulic concrete immersed in water for 28 days at a water-binder ratio of 0.5, its water diffusion coefficient, shape coefficient and wet expansion coefficient are 3.98×10-12 m2/s, 6.07 and 3.08×10-3, respectively.

Key words: hydraulic concrete, wet expansion strain, wet expansion coefficient, water diffusion coefficient, inversion analysis