混凝土特性数值方法研究及CT试验

Research on Numerical Method for Features of Concrete and Its CT Testing

建立三维混凝土数值模型,确定了三维"数字混凝土"数值试验的加载方法及强度的计算方法,并从细观层面上分析了混凝土强度特性、受力破坏机理及裂纹演化规律。最后用混凝土CT试验验证了此法的合理性。得出可以用位移控制的数值试验的应力应变曲线的极值点作为数字混凝土的强度点;混凝土强度主要受界面和砂浆强度控制;不论是拉还是压荷载作用下,混凝土裂纹均从骨料尖角处相对较弱的界面开始萌生,然后微裂纹绕着骨料扩展、贯通,说明混凝土的静态裂纹追随结构的弱面发展;混凝土试样的强度取决于试样的破坏面积,破坏面积越大强度越高。

A 3D concrete numerical model is set up. The strength calculation and loading methods of the threedimensional ＂digital concrete＂model are determined,and the strength characteristics,failure mechanism and crack evolution law of concrete are analyzed at the mesoscopic level. Finally the CT test has been done to verify the rationality of this method. It can be concluded that the extreme value point of stress strain curve of numerical experimentation controlled by the displacement can be used as the strength point of＂digital concrete＂; the concrete strength is mainly controlled by the strength of interface and mortar; whether under tensile or compressive load,the concrete cracks originate from the relatively weak interface of aggregate at its tips,then extend around the aggregate. It shows that the development of static crack of concrete goes along the weak plane of the structure; The strength of the concrete sample depends on its damaged area,the strength is directly proportional to the damaged area of the samples.