基于材料试验和细观模型的混凝土渗透性研究

Water Permeability of Concrete Based on Materials Experiment and Mesoscale Model

基于材料试验和细观模型,以球体和椭球体模拟粗骨料,以薄壳模拟界面区,建立三维混凝土三相细观模型,研究了压力水在混凝土中的渗透规律.结果表明:混凝土细观模型模型能较好地反映压力水在混凝土内渗透过程中的局部特征和总体规律,展现了由于骨料随机分布所导致的“曲折效应”、“稀释效应”和“界面效应”;随着骨料体积分数的增加,以上3种效应被同时放大,骨料对混凝土抗渗透性能的影响应综合考虑3种效应的影响;在骨料形状、骨料体积分数和界面区参数一定的情况下,混凝土的有效渗透系数与砂浆的渗透系数呈正比例关系;混凝土试件侧面防水措施不足所导致的边界效应使得抗渗高度法试验结果存在较大误差,应根据试件模具的尺寸误差、拟加水压值来确定边界防水层的厚度.

Based on materials experiment and mesoscale model,a three-dimensional three-phase mesoscale model of concrete was established,in which the spherical and ellipsoidal particles are adopted to simulate the aggregates and thin shells simulate the interfacial transition zone,water permeability of concrete was investigated.The results show that the mesoscale model of concrete can better reflect the local characteristics and overall pattern of water permeability of concrete,and illustrate the tortuous effect,dilutional effect and interfacial effect caused by the random aggregates;With the volume fraction of aggregates increases,these effects are simultaneously amplified,so the influence of aggregate on the water permeability of concrete should take these effects into consideration.Suppose that the shape and volume fraction of aggregates and the parameters of ITZ are constant,the permeability coefficient of concrete is proportional to the permeability coefficient of mortar.The boundary effect caused by insufficient side waterproof makes the experimental errors larger.The boundary waterproof layer should be determined according to the dimension error of the specimen mould and the value of water pressure.