考虑残余强度修正的混凝土冻融损伤层及轴心受压模型研究  

Study on Concrete Freezing-thawing Damage Layer Considering Residual Strength Correction and Constitutive Model under Axial Compression

作　　者：关虓[1] 牛荻涛[2] 肖前慧[1] GUAN Xiao;NIU Ditao;XIAO Qianhui(School of Architecture and Civil Engineering,Xi’an University of Science Technology,Xi’an 710055,China;School of Civil Engineering,Xi’an University of Architecture Technology,Xi’an 710055,China)

机构地区：[1]西安科技大学建筑与土木工程学院,陕西西安710055 [2]西安建筑科技大学土木工程学院,陕西西安710055

出　　处：《铁道学报》2021年第3期175-182,共8页Journal of the China Railway Society

基　　金：国家自然科学基金(51808443);中国博士后科学基金(2017M613166);西部绿色建筑国家重点实验室开放基金(LSKF201808)。

摘　　要：采用符合实际冻融环境的气冻气融试验方法,对混凝土受冻后损伤度的评估及轴心受压模型进行了系统研究。根据超声波平测法确定混凝土冻融损伤层厚度,以损伤层作为混凝土冻融损伤度评价指标,并考虑损伤层内的残余强度,引入损伤层修正系数α,提高了损伤度评估的可靠性;讨论损伤演化规律,建立了基于冻融损伤层的混凝土轴心受压本构模型。研究结果表明:引入修正系数α后,冻融损伤度的评估精确性显著提高;随着冻融次数增加,修正系数α逐渐减小,反映了损伤层内残余强度不断减小,实际损伤度逐渐增大的行为;峰值点后,混凝土抗压强度越大,试件总损伤度(冻融损伤与受荷损伤)的演化速率越快;所建本构模型计算结果与本文及其他文献试验结果吻合较好。In this paper,the assessment method and the axial compression performance of concrete under freezing and thawing conditions were studied by air-freezing and air-thawing test in accordance with the actual freezing and thawing environment.The freeze-thaw damage layer thickness was measured by ultrasonic single side method.The freezing-thawing damage layer was used as an index to evaluate the freezing-thawing damage degree of the concrete.Based on the residual strength in concrete damage layer,the damage layer correction coefficient α was introduced to improve the reliability of damage degree evaluation.Following the discussion of the damage evolution law,the constitutive model of concrete under axial compression based on freeze-thaw damage layer was established.The results show that after introducing the correction coefficientα,the evaluation accuracy of freezing-thawing damage degree is improved significantly.With the increase of freezing-thawing cycle,the correction coefficient α decreases gradually,which reflects that the residual strength in the damaged layer decreases and the actual damage degree increases gradually.After the peak point,the higher the compressive strength of the concrete,the faster the evolution rate of the total damage degree(freeze-thaw damage and load damage)is.The results of the constitutive model are in good agreement with the experimental results in this paper and other literatures.

关 键 词：气冻气融 残余强度 本构模型 损伤层厚度 损伤变量 

分 类 号：TU37[建筑科学—结构工程]