基于GM(1,1)的应力损伤轻骨料混凝土抗冻性评估

Freeze-thaw Resistance Evaluation of Lightweight Aggregate Concrete with Stress Damage Based on GM(1,1)

为在特定灾变程度下,对轻骨料混凝土抗冻融性能进行精确定量描述及预测,通过反复加载对轻骨料混凝土预加初始应力损伤来模拟灾变,以相对动弹性模量为评价指标,研究初始损伤度分别为0、0.05、0.12、0.19、0.27的轻骨料混凝土抗冻融性能;将灰色系统理论引入混凝土抗冻耐久性研究中,利用相对动弹性模量实测数据建立基于GM(1,1)的应力损伤轻骨料混凝土抗冻融性能预测模型,与修正的Loland混凝土损伤模型对比并进行精度分析;借助建立的GM(1,1)预测模型定量研究初始应力损伤对轻骨料混凝土抗冻耐久性的影响并预测其抗冻耐久寿命。结果表明:初始应力损伤会加速轻骨料混凝土抗冻融性能劣化,且初始损伤度越大劣化速率越快;各初始损伤度下GM(1,1)模型的平均相对误差均小于4.5%,GM(1,1)模型的预测精度整体上优于修正Loland模型;轻骨料混凝土自身具有良好的抗冻融性能,在内蒙古中西部地区抗冻耐久寿命可达45 a,当初始损伤度为0.05、0.12、0.19、0.27时,抗冻耐久寿命分别缩短至30、25、17.5、10 a。基于GM(1,1)的应力损伤轻骨料混凝土抗冻融性能预测模型可实现对灾变后轻骨料混凝土全寿命周期内抗冻融性能较为精确的定量评估,为指导北方寒旱区轻骨料混凝土工程实践提供理论依据。

The key to the evaluation of freeze-thaw performance of lightweight aggregate concrete after disaster lies in the accurate quantitative description and prediction of its freeze-thaw performance under the specific disaster degree.The initial stress damage of lightweight aggregate concrete was applied by repeated loading to simulate the disaster,and the relative dynamic elastic modulus was taken as the evaluation index to study the freezing-thawing performance of lightweight aggregate concrete with the initial damage degree of 0,0.05,0.12,0.19 and 0.27,respectively.The grey system theory was introduced into concrete frost resistance durability study,the relative dynamic elastic modulus measured data was used to build prediction model of freeze-thaw resistance of stress-damaged lightweight aggregate concrete based on GM(1,1),and corresponding comparation with the revised Loland concrete damage model and accuracy analysis was performed;The GM(1,1)prediction model was used to evaluate the effect of initial stress damage on the frost resistance durability of lightweight aggregate concrete and predict its frost resistance life.The results showed that the initial stress damage could accelerate the freeze-thaw performance degradation of lightweight aggregate concrete,and the higher the initial stress damage degree was,the faster the deterioration rate would be.The average relative error of GM(1,1)model was less than 4.5%under each initial damage degree,and the prediction accuracy of GM(1,1)model was generally higher than that of the revised Loland model.Lightweight aggregate concrete had a good freezing-thawing resistance,and its freezing-thawing resistance life could reach 45 years in central and western Inner Mongolia.When the initial damage degree was 0.05,0.12,0.19 and 0.27,the freezing-thawing resistance life was shortened to 30 years,25 years,17.5 years and 10 years,respectively.The prediction model of freeze-thaw performance of stress-damaged lightweight aggregate concrete based on GM(1,1)could accurately evaluate the whole process of freeze-thaw performance of the damaged lightweight aggregate concrete after disaster,which provided theoretical basis for guiding the engineering practice of lightweight aggregate concrete in cold and dry regions of north China.