液氮冻结技术在地铁端头井加固中的应用

液氮冻结具有系统简单、冻结速度快、温度低和冻土强度高等特点,在城市地下工程建设中得到广泛应用。为了对某一地铁端头井进行加固,保证盾构机进洞安全,利用液氮冻结技术进行加固。经现场温度实测与分析,冻结效果达到了设计要求。运用数值模拟软件对液氮冻结和常规盐水冻结效果进行模拟,结果表明,液氮冻结土体5d左右就基本交圈,而常规盐水冻结需要30d左右才可以交圈,充分显示了液氮冻结技术低温、快速等优点。

Application of Liquid Nitrogen Freezing Technology Used in Reinforcement of Some Subway End Well

Because of its simple system,rapid freezing speed,low temperature and frozen soil’s high strength,the liquid nitrogen freezing method has been widely used in underground engineering construction.In order to strengthen a subway end well and ensure the shield driving in the tunnel safety,the liquid nitrogen freezing method is applied to freeze the end well.By analyzing the temperature monitoring data,the result can meet design requirements.The numerical simulation method is used to compare the liquid nitrogen freezing method with conventional brine freezing method.The results show that frozen soil can overlap in five days by using liquid nitrogen,when the conventional brine freezing method needs thirty days,which proves the good features of the liquid nitrogen technology.