Abstract: In order to explore the working states of concrete in cyclic water pressure environment such as tide, impoundment and discharge, we carried out research on effects of cyclic water pressure on the mechanical properties and damage evolution of concrete in stress space and strain space respectively. During the research, we pretreated saturated concrete under pressurized water cycles for different times(0, 50,100,200 cycles) and directly conducted load test on concrete under confined water pressure with constant loading rate of 10^-4/s. Results show that: 1) the number of cycle has both positive and adverse effects on mechanical properties of concrete, and the main positive effect is Stefan effect, which would increase the peak stress and deformation ability of concrete, and in the meantime alleviate damage development; 2) Stefan effect takes a dominant role when the cycle number is less than or equal to 100 and increases with the increasing of cycle number, but weakens when internal pores of the concrete connect or run through with each other; 3)during the compression process, Stefan effect lags in a certain degree due to the relative slip of the conjugate surface in the concrete, but the overall impact is greater than the adverse effects; 4)the calculation method for damage variable proposed in this article is from the aspect of energy dissipation with plastic strain energy as a part of energy consumption of material damage, and it reflects the degradation of material deformation modulus. Moreover, it is consistent with engineering practice.

Key words: concrete, pore water pressure, water environment, stress difference, damage evolution