摘要
采用三点弯曲法对大庆红旗泡水库淡水冰试样进行弯曲试验。冰梁发生破坏时,主要经历三个阶段:第一阶段是在杂质和气泡边缘首先产生微裂缝;随着荷载的增加,出现新的微裂缝,并且受拉区达到抗拉强度,此为第二阶段;此后荷载继续增加,冰中微裂缝扩展延伸为宏观裂缝,当施加的荷载大于冰梁的抗拉强度时,冰梁即被破坏,这是第三阶段。在分析上述淡水冰破坏机理的基础上,对试验结果进行研究。结果表明,水库淡水冰弯曲强度与应力速率和冰温有着密切关系。在小于2kPa/s的应力速率范围内,随着应力速率的增大,弯曲强度减小。冰温在-5℃～-15℃范围内,对应的应力速率在30～70kPa/s范围内时,冰梁弯曲强度达到极限,同时也揭示了极限弯曲强度对应的应力速率随着温度的降低逐渐向低应力速率转化。达到极限弯曲强度后,应力速率继续增加,弯曲强度值呈减小趋势。弯曲强度随着冰温的降低呈增加趋势,且弯曲强度在-15℃时达到最大值2 270kPa。
Experiments of natural freshwater ice samples are made on Hongqipao Reservoir in Daqing by three-point bending method.Ice girder mainly experiences three stages when faced with breakage.The first stage is that tiny cracks are produced at the edge of impurities and air bubbles.New tiny cracks are also produced with the increase in the load,and the enduring pull area reaches tensile strength,called the second stage.With the increase in the load,the tiny cracks of inner ice extend and form macro-scopical cracks.Finally,ice girder is broken while the load exceeds tensile strength of ice.Based on analyzing the above mechanism of breakage fresh water ice,research is done on test results.The results show that flexural strength of fresh water ice is closely related to stress rate and temperature.In the range of 2 kPa/s stress rate,with the increase in stress rate,flexural strength decreases.Flexural strength is maximal when stress rate ranges from 30 to 70 kPa/s and the ice temperature ranges from-5 ℃ to-15 ℃,This also shows that stress rate corresponding maximal flexural strength gradually decreases with the decrease in temperature.After reaching maximal flexural strength,with the increase in stress rate,the flexural strength decreases instead.The flexural strength increases with the decrease in ice temperature and of the maximum is 2 270 kPa at the-15 ℃ temperature.
出处
《中国农村水利水电》
北大核心
2011年第3期70-72,共3页
China Rural Water and Hydropower
基金
国家自然科学基金资助项目(50879008)
关键词
水库
淡水冰
弯曲强度
应力速率
温度
reservoir
freshwater ice
flexural strength
stress rate
temperature
