温度与荷载共同作用下钢筋混凝土桩的细观损伤

为探究港口码头不同环境因素对码头桩身材料特性的劣化影响而降低桩身承载能力，通过PFC3D（颗粒流分析程序Particle Flow Code 3D)建立三维颗粒流离散元钢筋混凝土桩模型开展研究。对温度-应力模型进行建立，选取热学参数，构建了温度热管模型，通过分级加热，得到了钢筋混凝土桩的横向拉伸应变、纵向压缩应变以及微裂缝生长数量随温度变化曲线；调整模型混凝土粗骨料占比与强度等级，研究其对对钢筋混凝土桩受热损伤的影响；通过施加温度场的模型进行水平加荷载后，得到的应力应变曲线；基于模型微裂隙数量的损伤变量，并构建了损伤变量-轴向应变曲线，进一步分析了温度-荷载共同作用的损伤规律。结果表明：混凝土轴向压缩应变和横向拉伸应变会随温度的增加而逐渐升高，细观微裂隙数量会随温度的升高而增长；粗骨料占比升高会使受热初始损伤增加；温度的升高，材料的宏观力学性能出现了不同程度的降低。

Study on the fine view damage of reinforced concrete piles under the combined effect of temperature and load

In order to explore the influence of different environmental factors on the deterioration of wharf pile material properties and reduce the bearing capacity of the pile body, a three-dimensional particle flow discrete element reinforced concrete pile model was established through PFC3D (Particle Flow Code 3D) for research. A temperature stress model was established, and thermal parameters were selected to construct a temperature heat pipe model. Through graded heating, the transverse tensile strain, longitudinal compressive strain, and microcrack growth number of reinforced concrete piles were obtained as a function of temperature; Adjust the proportion and strength grade of coarse aggregate in the model concrete, and study its impact on the thermal damage of reinforced concrete piles; The stress-strain curve obtained by applying a temperature field model to a horizontal load; Based on the number of microcracks in the model, a damage variable axial strain curve was constructed to further analyze the damage law under the combined action of temperature and load. The results show that the axial compressive strain and transverse tensile strain of concrete gradually increase with the increase of temperature, and the number of micro cracks increases with the increase of temperature; An increase in the proportion of coarse aggregate will increase the initial damage caused by heating; The increase in temperature results in varying degrees of decrease in the macroscopic mechanical properties of the material.