基于粘结裂缝模型的混凝土断裂过程及参数研究

Concrete Fracture Process and Parameters Based on Cohesive Crack Model

为研究混凝土细观结构对混凝土断裂参数的影响,基于ABAQUS平台进行二次开发,自编0厚度粘结单元嵌入程序,建立混凝土细观粘结裂缝模型对文献中的水工二级配混凝土断裂过程进行数值模拟并验证数值模型的准确性。在此基础上结合边界效应模型预测混凝土的断裂参数以及分析骨料粒径、骨料形状对混凝土断裂参数的影响。结果表明:混凝土细观粘结裂缝模型能准确模拟混凝土损伤断裂全过程,数值模拟得到的荷载-裂缝口张开位移曲线关键点与文献中试验所得关键点平均值相对误差在10%以内;数值模拟结果经边界效应模型计算得到的混凝土抗拉强度、断裂韧度与文献中采用规范公式计算的相对误差在7%以内;随着骨料平均粒径的增大,混凝土材料的抗拉强度逐渐减小,断裂韧度逐渐增加。该研究可为混凝土断裂参数的预测提供参考。

In order to analyze the influence of concrete meso-structure on concrete fracture parameters,the embedded program of 0-thickness bonding element was developed based on ABAQUS platform,and the meso-structure bonding crack model of concrete was established to simulate the fracture process of hydraulic two-grade concrete in the literature and verify the accuracy of the numerical model.On this basis,combined with the boundary effect model,the fracture parameters of concrete are predicted,and the influences of aggregate particle size and aggregate shape on the fracture parameters of concrete are analyzed.The results show that the meso-bond crack model of concrete can accurately simulate the whole process of concrete damage and fracture,and the relative error between the key points of load-crack opening displacement curve obtained by numerical simulation and the average value of key points obtained by experiments in the literature is within 10%.The numerical simulation results show that the relative error of tensile strength and fracture toughness of concrete calculated by boundary effect model is less than 7%compared with that calculated by standard formula in the literature.With the increase of the average particle size of aggregate,the tensile strength of concrete decreases gradually,and the fracture toughness increases gradually.The research can provide reference for the prediction of concrete fracture parameters.