基于毛细孔张力理论的混凝土干缩模型

Concrete drying- shrinkage model based on the theory of capillary tension

以毛细孔张力理论为基础,采用ANSYS有限元软件建立了混凝土内单个毛细孔的数值分析模型,对混凝土的干缩应变和干缩应力进行了模拟计算.假定混凝土内液体表面张力为定值,凹液面主曲率半径依次下降为不同值,利用ANSYS有限元软件计算毛细孔相应的径向收缩位移,据此计算单个毛细孔的体积干缩应变及相应混凝土的体积干缩应变.其次,计算当凹液面主曲率半径下降幅度不变,而使毛细孔隙内液体表面张力依次降低,利用同样的方法计算相应的单个毛细孔的体积干缩应变及相应混凝土的体积干缩应变.根据上述计算结果,分别绘制混凝土的体积干缩应变随混凝土毛细孔隙内凹液面主曲率半径及液体表面张力的变化曲线,从而近似地找出了混凝土干缩应变与毛细孔内液体表面张力、凹液面主曲率半径之间的关系.从微观角度建立了混凝土干缩应变的估算模型.

The model of capillary pores in concrete was established and the strain of drying shrinkage of concrete was simulated and calculated by ANSYS,that is a variety of computer software for finite element analysis on the basis of the theory of capillary tension of concrete. It assume that the surface tension of water in concrete was a constant and the radius of principal curvature drop into different values in turn,the radial shrinkage displacement of capillary pores,the volume shrinkage strain of a single pore and the whole concrete were calculated. The corresponding volume shrinkage strain were work out of a single pore and the whole concrete by using the same method,when assuming that the extent to which the radius of principal curvature of the curved meniscus descend was same and that the surface tension take less and less value in turn,the curves were plot at of the volume shrinkage strain of concrete along with the change of the radius of principal curvature of the curved meniscus and the surface tension of capillary water respectively. So the relationship among the drying shrinkage of concrete,the surface tension of water solution and the principal curvature of the curved meniscus in capillary pores of concrete was found out approximately. From the microscopic point,the estimation model of concrete drying- shrinkage strain was established.