基于GM(1,1)模型室内加速试验下钢筋混凝土服役寿命预测

Prediction for reinforced concrete service life under laboratory accelerated test based on GM(1,1)model

为研究西部盐渍土地区钢筋混凝土损伤劣化规律及服役寿命,设计了干湿循环、盐类侵蚀、紫外线辐射及太阳照射耦合因素下的室内加速试验,定期测试试件相对动弹性模量(RDEM)、相对质量评价参数(RQEP)和腐蚀电流密度(icorr)等宏观指标及扫描电镜(SEM)与X射线衍射(XRD)等微观指标来表征钢筋混凝土损伤劣化规律及腐蚀机理,同时利用GM(1,1)模型对钢筋混凝土服役寿命进行预测。研究结果表明:RDEM、RQEP及icorr均可在一定程度上表征混凝土损伤劣化过程,RDEM呈现出先增大后减小的趋势,RQEP表现为缓慢增长-平缓下降-加速下降三阶段变化特点,而icorr呈现缓慢增长-加速增长两阶段变化。利用GM(1,1)模型预测C35试件钢筋与混凝土失效时间分别为175 d和231 d,C40试件失效时间分别为273 d和497 d。

An objective was to investigate the durability deterioration law and service life of reinforced concrete in the saline soil area of Western China,a experiment for accelerated corrosion under the influence of typical climate and environment in this region is designed,and the relative dynamic elastic modulus(RDEM),relative quality evaluation parameter(RQEP)and corrosion current density(icorr)of specimens are tested,which are combined with the scanning electron microscope and X-ray diffraction to reveal the degradation mechanism.Meanwhile,the GM(1,1)model is used to predict the service life of reinforced concrete.The result shows that the degradation process of concrete is well characterized by RDEM,RQEP and icorr,RDEM showed an increasing trend followed by a decreasing trend,RQEP shows a three-stage change of slow growth,gentle decline and accelerated decline,while icorr shows a two-stage change of slow growth and accelerated growth.The prediction results of GM(1,1)model show that the failure time of reinforced bar and concrete are 175 d and 231 d for C35 specimens,273 d and 497 d for C40 specimens,respectively.