考虑尺寸效应的再生混凝土受压破坏细观模拟研究

Study on the failure of recycled concrete under compression considering size effect mesoscopic simulation

再生粗骨料取代率、粗骨料粒径及截面尺寸对再生混凝土单轴压缩破坏行为产生影响。文章采用细观尺度数值模拟方法,建立了再生混凝土二维细观模型,模拟分析了再生混凝土单轴压缩破坏的应力-应变曲线、损伤拓展以及破坏的全过程。结果表明:静态加载下,再生混凝土的损伤由内向外拓展,先出现在最薄弱的界面过渡区,再发展到砂浆基质;截面尺寸、粗骨料粒径和再生粗骨料取代率的改变会影响到再生混凝土的破坏模式和力学性能;再生混凝土存在明显的尺寸效应,不同截面尺寸下,再生粗骨料的粒径和取代率的增大都会在一定程度上削弱尺寸效应行为,而当再生粗骨料取代率为100%时,尺寸效应得到有效抑制。

Recycled coarse aggregate substitution rate,coarse aggregate particle size and cross-section size affect the uniaxial compression failure behavior of recycled concrete.In this paper,a two-dimensional mesoscopic model of recycled concrete is established by using mesoscale numerical simulation method.The stress-strain curve,damage expansion and the whole process of failure of recycled concrete under uniaxial compression are simulated and analyzed.The results indicate that under static loading,the damage of recycled concrete expands from inside to outside,initially appearing in the weakest interfacial transition zone and then developing to the mortar matrix.The failure mode and mechanical properties of recycled concrete are affected by the changes of cross-section size,coarse aggregate particle size and recycled coarse aggregate substitution rate.There is a notable size effect in recycled concrete,the increase of particle size and substitution rate of recycled coarse aggregates under various cross-sectional dimensions generally mitigate this size effect.When the substitution rate of recycled coarse aggregate is 100%,the size effect can be effectively suppressed.