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在随机骨料模型的基础上,采用特征单元尺度对网格进行剖分,建立了非均质混凝土材料损伤破坏及宏观力学特性研究的三维细观单元等效化模型。对单轴拉伸、单轴压缩条件下湿筛混凝土试件的破坏过程及宏观力学性能进行了模拟分析;研究了混凝土梁的三分点弯拉力学特性,并与平面模型结果作了对比。研究表明:1)与平面计算模型相比,三维模型更真实地模拟混凝土材料在外荷载作用下的损伤破坏过程,更准确的描述非均质混凝土材料的宏观力学性能,且与实验结果吻合;2)骨料空间分布形式基本不影响混凝土材料的宏观弹性模量及强度,但影响其破坏过程和破损路径;3)与随机骨料模型等细观力学方法相比,该方法具有高效性。
On the basis of random aggregate model, the meshes are subdivided by the characteristic unit scale, and a 3D mesoscopic unit equivalent model for the study of damage and macroscopic mechanical properties of the heterogeneous concrete is established. The failure process and macroscopic mechanical properties of wet-screened concrete specimens under uniaxial tension and uniaxial compression were simulated and analyzed. The third-point bending mechanical properties of concrete beams were studied and compared with the results of plane model. The results show that: 1) Compared with the plane calculation model, the three-dimensional model more accurately simulates the damage process of concrete under external loads and more accurately describes the macroscopic mechanical properties of the heterogeneous concrete. ) The spatial distribution of aggregates basically does not affect the macroscopic elastic modulus and strength of concrete, but it affects the process of failure and damage path. 3) Compared with meso-mechanics methods such as stochastic aggregate model, this method has high efficiency.