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混凝土动态双轴拉压破坏准则细观数值模拟研究

MESOSCOPIC NUMERICAL SIMULATION ON DYNAMIC BIAXIAL TENSION-COMPRESSION FAILURE CRITERION OF CONCRETE

  • 摘要: 正常服役期内的混凝土结构往往处于复杂应力状态, 并且不可避免地会受到偶发动力载荷作用. 对于复杂载荷作用下的混凝土力学性能研究, 破坏准则是基础. 受试验设备等条件限制, 现有的动态双轴拉压破坏准则形式复杂、缺乏更高应变率和侧应力比范围且尚未综合考虑应变率和侧应力比的耦合作用. 为进一步提出适用范围更高且更准确的混凝土动态双轴拉压破坏准则, 在细观尺度上建立了混凝土立方体三维随机数值模型, 模拟了不同应变率和侧应力比下混凝土材料的动态双轴拉压破坏行为, 分别讨论了应变率和侧应力比对混凝土破坏模式和动态双轴强度的影响, 总结提出了混凝土动态双轴拉压破坏准则. 研究结论如下: 随应变率和侧应力比增大, 混凝土试件内部损伤增多, 裂纹数量增加. 动态双轴拉压工况下, 混凝土动态主轴压缩强度和侧轴拉伸强度均随应变率的增大而增大. 随侧应力比增大, 动态主轴压缩强度减小, 而动态侧轴拉伸强度增大. 本文提出的混凝土动态双轴拉压强度准则具有应变率和侧应力比适用范围大, 形式精炼简洁, 不再受物理试验条件限制和考虑了应变率和侧应力比的耦合作用等优点, 并且该准则得到了不同角度的验证.

     

    Abstract: Concrete structures in normal service are often subject to complex stresses and are inevitably subject to the sporadic dynamic loads. The failure criterion is the foundation for the study of mechanical properties of concrete under complex loads. Limited by the test equipment and other conditions, the existing dynamic biaxial tension-compression strength failure criterion has a complex form, lacks of higher strain rate and lateral stress ratio range and has not yet considered the coupling effect of strain rate and lateral stress ratio comprehensively. In order to further propose a more applicable and accurate failure criterion of concrete dynamic biaxial tension-compression strength, a 3D random numerical model of cubic concrete is established on a mesoscale in this study. The dynamic tension-compression failure behavior of concrete materials under different strain rates and lateral stress ratios are simulated. The influence of strain rate and lateral stress ratio on the failure modes and dynamic biaxial strengths of concrete are discussed respectively. The failure criterion of dynamic biaxial tension-compression strength of concrete is put forward. The simulation results indicated that with the increase of strain rate and lateral stress ratio, the internal damage of concrete specimen increases and the number of cracks increase. Under dynamic biaxial tension-compression loads, with the increasing strain rate, the dynamic spindle compressive strength and dynamic lateral tensile strength of concrete increase gradually. With the increasing lateral stress ratio, the dynamic spindle compressive strength decreases while the dynamic lateral tensile strength increases. The dynamic biaxial Tension-Compression failure criterion of concrete proposed in this paper has the advantages of wide range of applicable strain rate and lateral stress ratio, concise form, no longer restricted by physical test conditions and considering the coupling effect of strain rate and lateral stress ratio, etc. The established failure criterion of concrete has been verified from different angles.

     

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