碾压混凝土劈裂抗拉强度及其尺寸效应的细观数值研究

为了从细观结构上研究碾压混凝土的劈裂抗拉强度及其尺寸效应,采用随机骨料模型,在细观层次上将碾压混凝土看成是由硬化水泥粉煤灰砂浆体、粗骨料颗粒、二者间的黏结带和砂浆层面构成的三相非均质复合材料;利用有限元方法数值模拟研究碾压混凝土的细观损伤断裂和劈裂抗拉,对其劈裂抗拉强度及其尺寸效应进行了研究。结果表明:黏结带和层面是碾压混凝土劈裂抗拉破坏的薄弱环节;碾压混凝土试件的劈裂抗拉强度存在明显的尺寸效应,和一般的试验规律基本吻合;随机生成骨料结构的方法,可以有效地研究碾压混凝土的细观损伤断裂。

Numerical Study of Split-tensile Strength and Size Effect of Rolled Compacted Concrete on Meso-level

For studying the split-tensile strength of roller compacted concrete(RCC) and its size effect on meso-level,the random aggregate model was used and RCC was taken as three-phase heterogeneous composites consisting of mortar smut matrix and pulverized coal ash,aggregate,smut matrix plane and bond between matrix and aggregate on meso-level.The extension of cracks and the mechanical properties of RCC in split-tensile test were simulated using the finite element method to find out the split-tensile strength of RCC and its size effect.The result indicates that(1) the contact surface and plane are the weak place of split-tension of RCC;(2) the split-tensile strength of RCC specimen exists significant size effect which is consistent with the laws of the usual trials basically.The way of generating aggregates structure randomly is an effective method to study the micro-fracture injury of RCC.