围压下裂纹中自由水影响混凝土力学性能的机理

Meso-mechanism of effects of free water on mechanical properties of concrete under confined compression

为了研究围压和混凝土裂纹中自由水对混凝土材料静、动力宏观力学性能的影响,根据混凝土材料的细观结构、不同围压水平下混凝土的宏观破坏现象及混凝土中微裂纹的扩展和串接规律,揭示了围压下混凝土的破坏过程和破坏机理。通过对混凝土体积变形和裂纹扩展速度的讨论,得到了静动力荷载条件下自由水的有害及有益作用,利用断裂力学,考虑主控裂纹之间的相互影响、围压及自由水的不同作用、裂纹扩展速度对应力强度因子的影响,建立了低围压下混凝土的静、动力抗压强度模型。模型的计算结果与宏观试验现象较为一致。

Theoretical models were developed to describe the effect of free water in cracks and the effect of confined compression on the macro mechanical properties of concrete. A meso-failure mechanism for concrete based on the concrete mesostructure for confined compression was developed based on the macro failure phenomena of concrete for various confined compressions and various crack development processes. The negative and positive effects of water on the static and dynamic strengths of concrete were analyzed as a function of the bulk deformation of concrete and the cracking velocity. The stress intensity factor of cracks in saturated concrete is influenced by the cracking velocity, the free water and the stress fields around microcracks. The static and dynamic strengths model of concrete under confined compression is built according to fracture mechanics. The theoretical results agree well with experimental data.