| 摘要: |
| 利用动静力三轴试验机进行不同加载速率、不同侧向压力下混凝土的抗压试验，基于改进的Najar能量法，提出一种新的损伤变量计算方法，以此分析侧向压力和加载速率对混凝土双轴受压状态下损伤演化的影响。研究结果表明：① 峰值应力随加载速率的增大而增大；相同加载速率下，峰值应力随侧压力增大而增大，混凝土达到峰值应力后承载力下降趋势不受侧压影响；② 混凝土双轴受压状态下损伤演化可分为线弹性阶段、损伤加速变化阶段和损伤收敛阶段；③ 加载速率越大，损伤加速发展阶段损伤变量的增长越迅速且该阶段对应的应变范围越小；④ 侧向压力对混凝土损伤演化有明显影响，混凝土损伤的发展随着侧应力的增大而出现滞后现象。 |
| 关键词: 混凝土 Najar能量法 应变速率 双轴抗压 损伤 |
| DOI：10.12170/201904014 |
| 分类号:TU502 |
| 基金项目:国家自然科学基金资助项目（51579139）;三峡大学学位论文培优基金资助项目（2019SSPY033） |
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| Analysis of dynamic biaxial compression damage characteristics of concrete based on Najar energy method |
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CHENG Zhuoqun, PENG Gang, SUN Shangpeng, WANG Pu, LIU Miaomiao
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College of Civil Engineering & Architecture, China Three Gorges University, Yichan
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| Abstract: |
| The compression tests of concrete under different lateral pressures and different loading rates are carried out by using a dynamic and static triaxial testing machine. Based on the improved Najar energy method, a new calculation method for damage variables is proposed to analyze the influences of the lateral pressures and loading rates on the damage evolution of concrete under biaxial compression stress. The analysis results show that：(1) The peak stress increases with the increase of the loading rates. Under the same loading rates, the peak stress increases with the increase of the lateral pressures. When the concrete reaches the peak stress, the decreasing trend of the bearing capacity is not affected by lateral pressures. (2) The damage evolution of concrete under biaxial compressive stress state can be divided into three stages: the elastic stage, the damage acceleration stage and the damage convergence stage. (3) The higher the loading rate is, the faster the damage variable increases in the accelerated development stage and the smaller the strain range in this stage. (4) The lateral pressure has a significant influence on the damage evolution of concrete. The development of concrete damage lags with the increase of the lateral stresses. |
| Key words: concrete Najar energy method strain rate biaxial compression damage |
