基于数值流形元法的混凝土力学特性数值试验

Numerical simulation of test of concrete mechanical properties based on numerical manifold method

从混凝土细观结构出发,假定混凝土由砂浆、骨料界面组成的多相复合材料,以试验为基础赋予各相材料的参数模拟加载过程中从细观到宏观的力学响应。考虑各相组分的非均匀性,借助蒙特卡罗方法和Fuller级配公式,产生随机骨料模型。扩展后的二阶流形元法,可以模拟混凝土受力、变形和破坏的全过程,可以追踪多裂隙的扩展,裂缝闭合后的压剪。开裂面可利用应力结果自动搜索,而不必人为预设。利用改进的流形元进行混凝土力学特性数值试验的模拟研究,再现了混凝土单轴受压、受拉试验在不同加载阶段微裂缝产生、扩展直至破坏的过程,及其宏观应力-应变曲线的变化情况。数值模拟结果与试验统计结果相符。

In order to reflect the heterogeneity of concrete at mesoscopic level and simulate the mechanics response from the mesoscopic level to macroscopical level in the course of load,the random aggregate model is developed by means of the Monte Carlo method and Fuller Graded Formula with the assumption that the concrete is a multi-phase composite material composed of matrix,and the material parameters are defined based on the test.The Numerical Manifold Method NMM introduced in the present paper can not only correctly simulate the stress,deformation and failure of concrete,but also simulate the expansion of multi-crack in the concrete,and failure plane growth can be searched by stress results automatically,so it can simulate such high discontinuous problems very well.Further more,NMM is adopted to simulate the tests of concrete mechanical performance.The creation,expansion and fracture process of cracks in axial tensile,compression of concrete are simulated numerically.The computational results are in good agreement with the experimental data.