In the nonlinear computation of the spiral case structure of Three Gorge Power Station, damage mechanics is introduced to study the concrete cracks from microcosmic to macrocosmic scope. This can put forward significant reference to structural reinforcement design and damage detection. In this paper, with the new three dimensional orthogonal damage finite element program, the damage distribution, stress and strain of the spiral case structure are fully analyzed in the conditions of different internal pressures. According to the result, it can be concluded that the structure has high safety stock and its design is rational.
