为探究混凝土在潮汐、蓄放水等循环水压环境下工作的情况,对饱和混凝土进行了不同次数(0,50,100,200)的有压水循环预处理,并在有围压的水环境中直接对混凝土进行加载,加载速率恒定为10^-4 s^-1。分别在应力空间上和应变空间上探究了循环水压对混凝土力学性能和损伤演化的影响。研究结果表明:①循环次数对混凝土力学性能的影响包含了有利影响与不利影响,有利影响主要表现为混凝土内部的Stefan效应,会增加混凝土的峰值应力与变形能力,同时延缓损伤的发展;②Stefan效应在循环次数较少时(≤100)占据主导地位,且随循环次数的增加而增大,并在孔隙水使混凝土内部孔隙发生连通和贯穿后开始减弱;③在混凝土受压过程中,由于混凝土内部共轭面的相对滑移,Stefan效应有一定的滞后性,但总体的影响程度大于不利影响;④所推导的损伤变量计算方法从能量耗散角度出发,将塑性应变能作为材料损伤耗能的一部分,反映了材料变形模量的退化,且比较符合实际工程经验。

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.