冻融条件下混凝土破坏面演化模型研究

对混凝土材料冻融破坏的研究多用动弹性模量表示，与强度损失相比，动弹性模量在工程结构方面一般不直接使用。针对此情况，建立冻融混凝土在主应力空间内实用的破坏面演化模型，以描述冻融后混凝土的强度变化。为此，根据混凝土冻融破坏的机制，应用损伤力学方法量化冻融造成的损伤并建立演化方程，应用“有效应力”的概念建立混凝土冻融破坏面在主应力空间内的发展演化模型，并预测混凝土冻融后的强度特征。最后通过已有试验数据验证演化模型的合理性。

EVOLUTION MODEL OF CONCRETE FAILURE SURFACE UNDER FREEZE-THAW CONDITIONS

The freeze-thaw failure of concrete in many researches is described by dynamic elastic modulus, which is not applicable to estimating the loss of concrete strength in structural engineering. To avoid the deficiency, the paper attempts to establish an applicable failure surface in principal stress space for concrete to describe concrete strength change under different freeze-thaw cycles. Based on the discussion of meso-state of concrete under freeze-thaw cycles, a hypothesis about concrete failure surface under freeze-thaw cycles is brought forward. Then, the damage of concrete and build up evolution equations is presented. Finally, a concrete failure surface model is given to predict concrete strength under different freeze-thaw cycles. Compared with available test data, the validity of new model is proven.