基于冻融循环和疲劳荷载共同作用下泡沫混凝土的微观力学性能研究

Study on the micro-mechanical properties of foam concrete under the combination of freeze-thaw cycle and fatigue load

泡沫混凝土在循环荷载和冻融循环耦合作用下,易产生微裂缝,致使泡沫混凝土在承受时,易发生微裂缝的扩展破坏,进而降低材料的强度、刚度等力学特性,影响其在工程上的应用。故此,分析研究泡沫混凝土在循环荷载-冻融循环条件下的微裂缝发展规律,揭示循环荷载与冻融循环交互作用下轻质混凝土力学性能的演变规律,通过三维数值模型得到泡沫混凝土的微观结构和在冻融以及荷载作用下的力学机理。结果表明:随着荷载循环次数的增加,微裂缝数量增加速度逐渐加快,大致呈指数增长;耦合作用下残余强度呈现先增后减的趋势,在冻融循环50次、加荷载循环30次时,残余强度达到最大值,与冻融循环单独作用下相比偏小;伴随泡沫混凝土服役年限的增加,其内部损伤逐步积累,可致使结构提前发生破坏。

Foamed concrete is prone to micro-cracks under the combined action of cyclic load and freeze-thaw cycles,which will cause the expansion and failure of micro-cracks when the foamed concrete bears,which will reduce the strength and stiffness of the material and affect its engineering performance.application.Therefore,it analyze and study the development of micro-cracks of foamed concrete under cyclic load-freeze-thaw cycles,reveal the evolution of the mechanical properties of lightweight concrete under the interaction of cyclic load and freeze-thaw cycles,and obtain the microstructure of foamed concrete through a three-dimensional numerical model.And the mechanical mechanism under freeze-thaw and load action.The results show that with the increase in the number of load cycles,the increase in the number of micro-cracks gradually accelerates,roughly increasing exponentially.The residual strength shows a trend of first increasing and then decreasing under the coupling action.When the freeze-thaw cycle is 50 times and the load cycle is 30 times,the residual strength increases first.The residual strength reaches the maximum value,which is relatively small compared with the freeze-thaw cycle alone.As the service life of the foamed concrete increases,its internal damage gradually accumulates,which can cause the structure to be destroyed in advance.