高寒地区RCC坝越冬层碾压式导电混凝土电阻率细观分析

高寒地区碾压混凝土重力坝越冬层的保温是坝体温控防裂的关注要点。不同于传统的外部保温措施，本文提出一种用于RCC坝越冬层面的碾压式导电混凝土(Electrically conductive Roller-Compacted Concrete, ERCC),可通过自发热解决寒潮期坝体内外温差大的问题。ERCC的电热性能是区别于常规混凝土的主要特性，电阻率是其关键参数。首先制备了不同粗骨料含量的ERCC试件，测量不同龄期下电阻率的变化趋势，得出粗骨料含量对电阻率的影响；进而建立ERCC-2D细观数值模型，分析了界面过渡区(Interfacial Transition Zone, ITZ)对混凝土电阻率的影响，通过数值计算对ITZ进行参数率定；最后通过耦合连续介质与非连续介质计算方法，建立出不同粗骨料含量下的ERCC-3D细观数值模型，通过试验验证细观数值模拟的正确性。可以发现，混凝土中骨料含量增加可显著增大ERCC 28 d龄期的电阻率；ITZ的电阻率为砂浆电阻率1.5倍，且ITZ电阻率对混凝土电阻率几乎无影响；为量化ERCC电阻率与骨料含量和砂浆的关系，结合试验与细观数值模拟提出了ERCC...

Meso-scale simulation ofresistivity of ERCC for RCC overwintering layer in alpine-cold region

The insulation of over-winter layer is one of the key points for the temperature control of RCC dams in alpine region. Compared with traditional external insulation measures,electrically conductive rollercompacted concrete (ERCC) is a novel functional material,which can solve problems of large temperature difference between inside and outside RCC through heating. The electro-thermal property of ERCC is the main characteristic that distinguishes it from conventional concrete,with electrical resistivity being the key parameter.Firstly,ERCC with different value fraction of coarse aggregate (VFCA) were designed to measure the electrical resistivity (ER) at different ages,and effect of VFCA on ER was obtained.Then,ERCC-2D mesoscopic model was established to analyze the impact of Interfacial Transition Zone (ITZ) on ER of ERCC. Finally,ERCC-3D meso-numerical models with different VFCA were created by coupling the calculation method of continuous medium and discontinuous medium,which has been proved by experiment.The result shows that VFCA significantly increase the ER of ERCC during the period of 28 d,and the ER of ITZ is quantified,which is 1.5 times of mortar.In order to determine the relationship between ERCC resistivity and aggregate content,a mathematical model of ERCC resistivity is proposed,combining experiment and mesoscopic simulation.The change of specimen size and gradation of aggregates has no effect on the resistivity of ERCC when the VFCA remains constant.