【摘要】 对内含水体的混凝土试样进行单轴压缩加载,利用红外热像仪并辅以声发射仪,观测加载过程中试样的红外辐射与声发射变化特征,研究混凝土破裂与渗水的红外异常前兆。实验结果显示,随着应力的阶段性发展,试样表面的红外辐射呈现早期整体性均匀上升、中期局部高温异常、后期低温异常的主要特征,声发射相应出现早期微量增加、中期均匀增加、后期快速增加的特征。加载中、后期红外热像出现的局部辐射温度"先升后降"现象是混凝土破裂–渗水的重要红外异常前兆,其出现的时间要早于应力和声发射前兆。整个破裂与渗水过程中,高温区域包围低温区域的温度场分布是热像的主要特征。基于实验结果,分析试样红外辐射阶段性变化以及破裂、渗水异常前兆的机制,讨论应力、红外及声发射灾变前兆时间差异性的原因。实验结果对水库大坝以及其他储水混凝土工程破裂与渗水的遥感监测与灾变预警具有重要的意义。更多还原

【Abstract】 To study the variation features of infrared radiation(IR) and acoustic emission(AE) of concrete during the fracturing and water seepage process,a concrete block is pressurized with embodied water to uniaxially compressive stress.The changes of its IR radiation and AE are measured using an infrared thermal imager and a AE instrument.The experimental results show that IR radiation of the sample′s surface regularly varies with the stress in different stages.The IR radiation shows an overall rise in early term,then partial high temperature in medium term,and partial low temperature in late term.The corresponding AE shows a little increase in the early term,then steadily increase in the medium term,and rapidly increase in the late term.It is revealed that the IR radiation experiences decreasing after early increase is the anomalous precursor of the fracturing and water seepage of concrete.The IR anomalous precursor happens earlier than stress and AE anomalous precursor.The thermal images of the sample also show that the low-temperature areas are surrounded by the high-temperature areas during the fracturing and water seepage process,which is the main feature of radiation temperature field.The mechanism of IR radiation variation in the loading process and the IR anomalous precursor of fracturing and water seepage are analyzed.The time difference between stress precursor,IR radiation precursor and AE precursor is also discussed.The experimental results are useful for the remote sensing monitoring and disaster forecasting on concrete dam and other concrete engineering.更多还原