高流速富水砂层地铁隧道液氮冻结温度场演化规律研究  

Evolution law of liquid nitrogen freezing temperature field in subway tunnel with high flow rate and water-rich sand layer

作　　者：杨哲 蔡海兵[1] 王彬[1,2] 李孟凯[1] 庞昌强 YANG Zhe;CAI Haibing;WANG Bin;LI Mengkai;PANG Changqiang(School of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan 232001,China;Henan Key Laboratory of Underground Engineering and Disaster Prevention and Control,Henan Polytechnic University,Jiaozuo 454150,China)

机构地区：[1]安徽理工大学土木建筑学院,安徽淮南232001 [2]河南理工大学河南省地下工程及灾变防控重点实验室,河南焦作454150

出　　处：《铁道科学与工程学报》2025年第1期307-319,共13页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52378384);安徽省自然科学基金资助项目(2308085ME188);河南省地下工程与灾害防控重点实验室开放基金资助项目(KFKT2023-06)。

摘　　要：地铁隧道施工常受到地下水渗流的侵扰,常规盐水冻结无法满足大流速下的施工要求,而液氮超低温可使砂层快速冻结以达到砂层稳定和加固效果。因此,进行复杂的水热耦合分析以探究渗流条件下液氮冻结温度场的演化规律至关重要。基于能量和质量守恒定律建立了液氮冻结温度场-渗流场水热耦合数值模型,对不同渗流速度下液氮冻结温度场的演化规律及冻结帷幕的交圈时间进行研究。结果表明:渗流速度为10、12.5、15、17.5和20 m/d的冻结帷幕交圈时间分别为5.76、6.85、8.31、11.43和18.57 d,冻结帷幕的交圈时间随渗流速度增大呈指数型增长。通过对模拟数据进行拟合,得出渗流场作用下液氮冻结帷幕交圈时间的预测公式,并计算出极限流速为22.26 m/d。渗流作用会引起冻结帷幕的不均匀性,渗流速度越大,不均匀性越强。各组渗流速度条件下的(R_(d)/R_(u))分别为1.23、1.35、1.53、1.76和2.12。对液氮冻结过程分析得到,“邻管效应”发生在冻结锋面减小至L_(j)后,该效应能够促使冻结锋面的扩展进入二次加速阶段,提高冻结锋面的扩展速度,加速冻结帷幕交圈;渗流产生的对流传热会减弱“邻管效应”,因此L_(j)会随着渗流速度的增加而减小,渗流速度为15.0、17.5和20.0 m/d,对应的Lj分别为389、355和254 mm。研究成果可为大流速下地铁隧道液氮冻结法施工提供有效的指导和帮助。Groundwater seepage frequently poses significant challenges to metro tunnel construction.Traditional saltwater freezing method is inadequate for high flow rates,whereas employing liquid nitrogen at ultra-low temperatures rapidly stabilizes and reinforces the sand layer.Therefore,it is crucial to conduct a comprehensive hydrothermal coupling analysis to investigate the evolution of the liquid nitrogen freezing temperature field under seepage conditions.Based on the principles of energy and mass conservation,a numerical model coupling the liquid nitrogen freezing temperature field with the seepage field was established to study the development of the freezing temperature field and the closure time of the freezing curtain under different seepage velocities.The results show that the closure times of the freezing curtain for seepage velocities of 10,12.5,15,17.5,and 20 m/d are 5.76,6.85,8.31,11.43,and 18.57 days,respectively.The closure time increases exponentially with the seepage velocity.By fitting the simulation data,a predictive formula for the closure time of the freezing curtain under seepage conditions is derived,and the limiting flow rate is calculated to be 22.26 m/d.Seepage causes inhomogeneity in the freezing curtain,with the ratios(R_(d)/R_(u))for seepage velocities of 10,12.5,15,17.5,and 20 m/d being 1.23,1.35,1.53,1.76,and 2.12,respectively.The analysis of the liquid nitrogen freezing process indicates that the'adjacent pipe effect'occurs when the freezing front is reduced to Lj,enhancing the expansion of the freezing front,accelerating the intersection of the frozen curtain.The convective heat transfer caused by seepage weakens the‘adjacent pipe effect’,resulting in a decrease of L_(j) with increasing seepage velocity.The L_(j) values corresponding to seepage velocities of 15.0,17.5,and 20.0 m/d are 389,355,and 254 mm,respectively.These findings can provide valuable guidance for the construction of subway tunnels using the liquid nitrogen freezing method under high flow velocities.

关 键 词：液氮冻结 大流速 数值模拟 水热耦合 邻管效应 冻结帷幕 

分 类 号：U45[建筑科学—桥梁与隧道工程]