斜井液氮补强冻结温度场分布特征  

DISTRIBUTION CHARACTERISTICS OF TEMPERATURE FIELD IN LIQUID NITROGEN REINFORCEMENT FREEZING OF INCLINED SHAFT

作　　者：石荣剑[1,2] 岳丰田[1,2] 张勇[1,2] 陆路[1,2] 

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221008 [2]中国矿业大学力学与建筑工程学院,江苏徐州221116

出　　处：《岩石力学与工程学报》2014年第3期567-574,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家高技术研究发展计划(863)项目(2012AA06A401)

摘　　要：针对地下有流水时盐水帷幕冻结方法无法形成封闭冻结壁的情况,采用液氮低温快速冻结的方式对未封闭区域进行补强冻结,对施工过程中土体的温度场分布进行监测和分析,得出以下基本结论:冻结管出口氮气温度低于-100℃时,冻结管内处于氮气和液氮的混合状态,可以有效发挥液氮快速冻结的优势,而供液管上开孔的结构,会影响冻结管内不同位置液氮量的分布,从而影响冻结效果。由于地下水流动会带走部分冷量,冻结区域封闭前后,土体降温速度差别较大,并且地下水的流动会影响冻结壁温度场的分布规律。由于液氮气化温度低,所以冻结形成的冻结壁温度梯度大,均匀性较差;停止冻结后,冻结孔位置土体温度升高迅速,而远离冻结孔的土体升温缓慢,这样缩小了冻结壁内的温度梯度。研究结果表明,利用液氮快速冻结的特点,进行盐水帷幕冻结下的补强冻结,可以有效封堵地下流水,解决盐水冻结不能形成封闭冻结帷幕的难题。The brine curtain freezing cannot form a closed frozen wall in inclined shaft because of flowing water in the ground may take away some cold energy. The method of liquid nitrogen freezing was used to strengthen the brine curtain freezing. Conclusion are drawn through analysis of soil temperature distribution data which was gained in the process of freezing construction. Firstly,mixed states of nitrogen gas and liquid nitrogen appeared in freezing pipe when the pipe export temperature is lower than -100 ℃. Opening holes on the liquid nitrogen supplying tube can affect the distribution of liquid nitrogen. As a result it may affect the freezing effect. Secondly, due to flowing water may take away some cold energy;the difference in the expansion speed of frozen soils is larger between pre and post the time that the closed frozen curtain was formed. And the flowing water can affect the temperature distribution of frozen wall. Thirdly,the frozen wall with high temperature gradient were uneven because of the low gasification temperature of liquid nitrogen. The termination of liquid nitrogen supply reduces the temperature gradient in the frozen wall. The soil temperature near the freezing hole rises faster than far away＆amp;nbsp;from the freezing hole after the freezing stopped. The research results indicate that the reinforcement freezing can effectively block flowing water by mean of the frozen wall formed by liquid nitrogen freezing. The problem can be solved that the closed curtain cannot be formed using brine curtain freezing.

关 键 词：地下工程 斜井 帷幕冻结 液氮冻结 补强冻结 动水 温度场 

分 类 号：TU91[建筑科学—建筑理论]