近场动力学水-热-力耦合模型与混凝土冻结破坏模拟

COUPLED HYDRO-THERMO-MECHANICAL PERIDYNAMIC MODEL FOR CONCRETE FREEZING FAILURE

  • 摘要: 低温环境下,作为多孔介质材料的混凝土内部孔隙水冻结会导致膨胀变形,从而诱发损伤甚至失效。为研究其冻结破坏过程和机理,该文应用近场动力学理论建立了能够描述混凝土冻结行为的积分形式的湿-热-力耦合模型,并发展了相应的多速率显式求解方案。三维混凝土试件的模拟结果表明温度以及孔隙水压力与有限元结果吻合良好。此外探究了渗透率对混凝土冻结过程中力学性能及破坏行为的影响,结果表明:渗透率对混凝土结构抗冻融性能影响较大,渗透率较高时,孔隙水压力、结晶压力和冻结应变减小;且试件裂缝减少,整体损伤程度也相应降低。该文模型可为深入分析混凝土在冻融循环下的破坏过程和破坏机理奠定基础。

     

    Abstract: Under low temperatures, the freezing of internal pore liquid water in concrete as a porous medium material leads to expansive deformation, which induces damage or even failure. To investigate the freezing damage process and mechanism, this study proposes a coupled hydro-thermo-mechanical model in integral form that can describe the freezing behaviors of concrete by applying peridynamic method, and develops a corresponding multi-rate explicit solution scheme. The numerical results of three-dimensional concrete specimens show that the temperature and pore liquid water pressure are in good agreement with the finite element results. In addition, the effect of permeability on the mechanical properties and damage behavior of concrete during freezing is investigated, and the results show that the permeability has a greater influence on the freeze-thaw resistance of concrete structures. When the permeability is higher, the pore liquid water pressure, crystallization pressure and freezing strain decrease, and the specimens have fewer cracks, and the degree of overall damage is reduced accordingly. The model can provide the basis for damage analysis of concrete under freeze-thaw cycles.

     

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