非均质混凝土材料破坏的三维细观数值模拟

NUMERICAL SIMULATION OF THREE-DIMENSIONAL MESO-MECHANICAL MODEL FOR DAMAGE PROCESS OF HETEROGENEOUS CONCRETE

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。

Based on a meso-mechanical model of random aggregate, the mesh grid was partitioned by a characteristic unit scale of the material, and a three-dimensional meso-unit equivalent model was established for the researches on the damage process and macro-mechanical properties of heterogeneous concrete. The nonlinear finite element was used to numerically simulate the propagation process of cracks ＆ fracture configuration and macro-mechanical properties in wet-screened concrete specimen under uniaxial tension /compression and in concrete trisection beams under bending load. The simulation results were compared with the two-dimensional results. It was found that： 1） compared with the plane model, a 3-D model could simulate the damage process of concrete under external loads more realistic, and could describe the macro-properties of heterogeneous concrete more accurate, and the computational results were in a good agreement with the experimental data; 2） the spatial distribution form of aggregate had a great influence on the damage process and damage path, but little impact on the macro elastic modulus and strength of concrete; 3） the method used in the paper had high efficiency, compared with other meso-mechanical models, such as a random aggregate model.