| 摘要: |
| 利用颗粒流方法,实现了相同条件下混凝土的骨料大小和空间位置对其破坏形态、应力应变曲线、峰值应力和割线模量的影响规律研究.通过对比砂浆与骨料的不同质量比(5∶5,4∶6,3∶7,2∶8)以及不同级配(一级配、二级配、三级配、四级配)骨料的混凝土单轴压缩仿真试验结果,发现骨料有阻止混凝土裂纹扩展的作用,且骨料越大,阻止混凝土裂纹扩展的作用越强,而微裂纹多绕骨料产生和发展；砂浆中加入骨料对混凝土强度和变形特性具有明显的改善作用,相对于砂浆的峰值应力52MPa和割线模量307GPa而言,在砂浆与骨料质量比为5∶5和4∶6时,不同级配混凝土的峰值应力约增加22%～48%、割线模量增加-8%～99%,其平均值基本维持在65MPa和72MPa,374GPa和426GPa；在砂浆与骨料质量比为3∶7和2∶8时,不同级配混凝土的峰值应力急剧增加40%～228%、割线模量急剧减小79%～92%,其平均值分别为92MPa和154MPa，158GPa和44GPa.当砂浆与骨料的质量比相同时,骨料级配越高,越容易形成架空结构,造成局部不稳定,影响骨料增强效果；级配相同时,混凝土强度随骨料质量占比的增大而增大,且其应力应变曲线呈现出单峰到双峰再到单峰的变化趋势,这说明骨料空间结构的稳定程度决定了混凝土应力应变曲线的形状变化. |
| 关键词: 颗粒流 混凝土 骨料 峰值应力 割线模量 |
| DOI：103969/j.issn1007 9629201601024 |
| 分类号: |
| 基金项目:桥梁工程湖南省高校重点实验室开放基金资助项目(13KA01)；长沙理工大学土木工程重点学科创新性项目(13ZDXK09) |
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| Analysis on Effect of Aggregate on Mechanical Property of Concrete |
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ZHOU Shangzhi1, CHEN Lin1, LIU Mingqun2
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1.School of Civil Engineering and Construction Engineering, Changsha University of Science and Technology,Changsha 410004, China;2.CCCC Second Highway Engineering Co., Ltd., Xian 710061, China
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| Abstract: |
| Influence laws of failure shape, stress strain curve, peak stress and secant modulus affected by size and spatial location of aggregate in concrete were studied under same condition based on particle flow concrete. Through analyzing the results of uniaxial compression simulation experiment of the concrete with different mortar and aggregate mass ratios(5∶5,4∶6,3∶7,2∶8) and different gradations(gradation 1, gradation 2, gradation 3 and gradation 4), it is found that aggregate has the effect of preventing crack propagation, the larger the aggregate, the greater the effect of preventing crack propagation, micro cracks was found to occur at around the aggregate and propagate. It is proved in many micro tests, that adding aggregate in mortar can greatly improve concrete strength and deformation characteristics. Comparing to peak stress 52MPa and secant modulus 307GPa of mortar, the peak stress of different gradations with 5∶5 and 4∶6 of mass ratio increases by 22%48% and secant modulus inereses by -8%99% with average value being 65MPa and 72MPa, 374GPa and 426GPa, the peak stress of different gradations with 3∶7 and 2∶8 of mass ratio sharply increases by 40%228% and secant modulus dramatically decreases by 79%92% with average value being 92MPa and 154MPa, 158GPa and 44GPa, which proves that under the same mass ratio, the higher the aggregate gradations, the easier it is to form structure built on stilts, causing local instability and affecting the enhancement effect; under the same grading, the strength of concrete increases with the increase of the mass ratio, and the stress strain curve firstly changes from unimodal to bimodal and then back to unimodal, which suggests that the stability of aggregate spatial structure determines change of stress strain curve. |
| Key words: particle flow concrete aggregate peak stress secant modulus |
