Innovative designs of permafrost roadbed for the Qinghai-Tibet Railway

来源 :Science in China(Series E:Technological Sciences) | 被引量 : 0次 | 上传用户:dt
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
Under global warming scenarios, the passive method of simply increasing the thermal resistance by raising the embankment height and using insulating materials has been proven ineffective in warm and ice-rich permafrost areas and therefore could not be used in the Qinghai-Tibet Railway engineering. Instead, a proactive “cooled-roadbed” approach was developed and used to lower the ground temperature in order to maintain a perennially frozen subgrade. The concept that local and site-specific factors play an important role in the occurrence and disappearance of permafrost has helped us to devise a number of measures to cool down the roadbed. For example, we adjust and control heat transfer by using different embankment configurations and fill materials. The Qinghai-Tibet Railway project demonstrates that a series of proactive roadbed-cooling methods can be used to lower the temperature of permafrost beneath the embankment and to stabilize the roadbed. These methods include solar radiation control using shading boards, heat convection control using ventilation ducts, thermosyphons, air-cooled embankments, and heat conduction control using “thermal semi-conductor” materials, as well as combinations of above mentioned three control measures. This road-bed-cooling approach provides not only a solution for engineering construction in sensitive permafrost areas but also a countermeasure against possible global warming. Under global warming scenarios, the passive method of simply increasing the thermal resistance by raising the embankment height and using insulating materials has proven proven ineffective in warm and ice-rich permafrost areas and therefore could not be used in the Qinghai-Tibet Railway engineering. Instead , a proactive “cooled-roadbed” approach was developed and used to lower the ground temperature in order to maintain a perennially frozen subgrade. The concept that local and site-specific factors play an important role in the occurrence and disappearance of permafrost has helped us to devise a number of measures to cool down the roadbed. For example, we adjust and control heat transfer by using different embankment configurations and fill materials. The Qinghai-Tibet Railway project demonstrates that a series of proactive roadbed-cooling methods can be used to lower the temperature of permafrost beneath the embankment and to stabilize the roadbed. These methods include solar radiatio n control using shading boards, heat convection control using ventilation ducts, thermosyphons, air-cooled embankments, and heat conduction control using “thermal semi-conductor ” materials, as well as combinations as above mentioned three control measures. -cooling approach provides not only a solution for engineering construction in sensitive permafrost areas but also a countermeasure against possible global warming.
其他文献
蜥蜴恐怕是最能适应环境的一类动物了,无论在海洋、丛林或沙漠、地底,甚至空中,到处都有它们的身影。从具有爬墙和断尾再生本领的守宫到能改变身体颜色的变色龙,从体长2米多