长期恒荷载作用下混凝土时变断裂试验研究  

Experimental study on time-dependent fracture under long time constant loading

作　　者：韩小燕 高洪波[1] 吴智敏[2] 马鹏[1] HAN Xiaoyan;GAO Hongbo;WU Zhimin;MA Peng(Hainan University,Haikou 570228,China;Dalian University of Technology,Dalian 116024,China)

机构地区：[1]海南大学,海南海口570228 [2]大连理工大学,辽宁大连116024

出　　处：《水利学报》2020年第2期223-231,共9页Journal of Hydraulic Engineering

基　　金：国家自然科学基金项目(51268010);海南省研究生创新科研课题(Hys2018-166)。

摘　　要：服役中的大体积混凝土结构处在长期荷载作用下,与服役时间相关的时变断裂问题直接关系到结构的安全。采用标准三点弯曲梁试件,分别施加约0.7Pmax、0.75Pmax、0.8Pmax、0.85Pmax、0.95Pmax的恒定荷载进行长期加载,试验测得在不同恒荷载水平下的时变裂缝口张开位移CMOD(t)。试验结果表明,CMOD(t)在持载阶段不断增大,CMOD(t)-t曲线呈现出三个阶段特征:第一阶段,CMOD(t)快速增大而裂缝口张开速率CMOR(t)逐渐减小;第二阶段,CMOD(t)增大而CMOR(t)几乎不变;第三阶段,CMOD(t)和CMOR(t)都快速增大直至试件断裂破坏。与不考虑时间相关性的单调加载静态断裂试验相比,时变断裂试验的临界裂缝口张开位移CMOD(tc)偏大;随着恒荷载水平的增大,时变断裂临界裂缝口张开位移CMOD(tc)减小且接近单调加载静态断裂的临界裂缝口张开位移。对于不同恒荷载水平的试件,其时变断裂寿命tcr随着长期恒荷载水平的增大而减小,且时变断裂寿命与荷载比P/Pmax成指数关系。Time-dependent fracture in mass concrete,which happens under long-time constant loading due to creep in the bulk of the specimen and time-dependent crack growth,is closely associated with the safe ty and durability of concrete structures in service.The standard three-point bending beams are tested under constant loads representing 70%,75%,80%,85%and 95%of the peak loads of the specimens for mono tonic short-time loading.Time-dependent crack mouth opening displacement CMOD(t)in concrete under dif ferent long-time constant loading is obtained.Experimental results show that CMOD(t)increases with in creasing loading time t.The time curve of crack mouth opening displacement CMOD(t)-t displays the fea tures of three stages.CMOD(t)increases rapidly in the primary stage,but the crack mouth opening rate CMOR(t)slows down.In the secondary stage,CMOD(t)increases and CMOR(t)is almost constant.In the tertiary stage,CMOD(t)and CMOR(t)all increase rapidly until the rupture of the specimen.For the test of time-dependent fracture,the critical crack mouth opening displacement CMOD(t)is relatively higher compared to the monotonic static loading test.The CMOD(tc)decreases with the increasing percentage of the peak load and approaches critical crack mouth opening displacement CMODc of monotonic static loading test.For the specimens loaded to the different percentage of the peak load,the lifetime decreases with in creasing long-term constant load.The lifetime as well as the percentage of the peak load are exponential.

关 键 词：时变断裂 时变裂缝口张开位移 时变裂缝口张开速率 时变断裂临界裂缝口张开位移 时变断裂寿命 

分 类 号：TV431[水利工程—水工结构工程]