变幅循环加卸载下的力学及变形性能对硫酸盐服役地区混凝土结构至关重要。将混凝土试件提前浸泡于10%、15%、20%硫酸钠溶液5、7个月形成化学侵蚀损伤,再开展单轴压缩变幅循环加卸载试验,分析该过程中试件力学性能、变形性能以及耗散能演化规律。结果表明随着硫酸钠浓度和侵蚀时间增加,试件强度降低、破坏时完成的变幅循环次数减少。累积残余应变随着加载应变增大呈上升趋势,变化速率不断提高;加载应变差始终大于累积残余应变差,随着循环次数增加逐步接近;动弹性模量和塑性变形率随着循环次数增加整体呈提高趋势;耗散能随着循环次数增加而增大,尤其是在后期耗散能变化速率增快。
Abstract
The mechanical and deformation properties under cyclic loading and unloading with variable amplitude are crucial for concrete structures under sulfate attack. The evolution of the mechanical properties,deformation properties and dissipation energy of concrete specimens under chemical erosion immersed in 10%,15% and 20% sodium sulfate solution for 5 and 7 months in advance was examined via uniaxial compression cyclic loading and unloading test with variable amplitude. Results demonstrated that with the increase of sodium sulfate concentration and erosion time,the strength of the specimen declined,and the number of cycles at failure decreased. The cumulative residual strain increased with the rising of loading strain,and such increment intensified continuously. The loading strain difference was always larger than the cumulative residual strain difference,but approached closer gradually with the proceeding of cyclic loading and unloading. The dynamic elastic modulus and plastic deformation rate both increased with the cyclic loading. The dissipated energy also increased with the cyclic loading,and especially boosted in the later stage.
关键词
混凝土 /
硫酸盐侵蚀 /
变幅循环加卸载 /
力学性能 /
变形性能
Key words
concrete /
sulfate attack /
cyclic loading and unloading with variable amplitude /
mechanical properties /
deformation properties
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基金
安徽省自然科学基金项目(2208085ME146,1908085QE185);深部煤矿采动响应与灾害防控国家重点实验室自主课题(SKLMRDPC20ZZ05);中国博士后科学基金面上项目(2018M642502);国家自然科学基金面上项目(51674006);大学生创新创业训练计划项目(202010361023,s202010361044)
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