界面过渡区与骨料特征对混凝土强度及变形影响的数值模拟研究

Numerical Simulation Study on Effects of Interface Transition Zone and Aggregate Characteristics on Strength and Deformation of Concrete

界面过渡区是混凝土结构中力学性能最薄弱的区域,其强度直接影响混凝土的力学性质,骨料强度及均匀性同样是混凝土结构设计需重点关注的参数。本文基于离散元方法,研究了骨料强度、界面过渡区强度、骨料均匀性及尺寸对混凝土强度及变形的影响规律。结果表明:骨料破碎为试样内部微裂纹的扩展与合并提供了新的路径,大量网状裂隙面的形成加速了试样的破坏;试样的峰值强度及弹性模量随界面过渡区强度的增加呈线性增加趋势,界面过渡区强度的增加可减小试样的径向变形,随界面过渡区强度提高,混凝土应力应变曲线的峰后段逐渐由韧性向脆性转变;骨料强度对峰值强度影响较小,对弹性模量几乎没有影响。骨料均匀性好的试样的径向变形小于均匀性差的试样,试样的峰值强度及弹性模量随骨料尺寸增加而增加,但是增加幅度远低于界面强度对峰值强度带来的提升。

The interface transition zone is the weakest area in mechanical properties of concrete structures,and its strength directly affects the mechanical properties of concrete.The strength and uniformity of aggregates are also the parameters that need to be focused for concrete structure design.Based on the discrete element method,the effect of aggregate strength,interfacial transition zone strength,aggregate homogeneity and size on concrete strength and deformation were studied.The results show that the crushing of aggregate provides a new path for propagation and merging of microcracks in sample,and the formation of a large number of network crack surfaces accelerates the destruction of sample.The peak strength and elastic modulus of sample increase linearly with the increase of interface transition zone strength,and the increase of interface transition zone strength reduces the radial deformation of sample.The post peak stage of stress-strain curve of concrete changes gradually from toughness to brittleness with the increase of interface transition zone strength.The aggregate strength has little effect on the peak strength and elastic modulus.The radial deformation of sample with good homogeneity of aggregate is smaller than that of sample with poor homogeneity.The peak strength and elastic modulus of sample increase with the increase of aggregate size,but the increase is far less than the increase of peak strength brought by interface strength.