液氮冻结技术在隧道工作井二次封堵水中的应用

为封堵工作井异常涌水涌砂缝隙,以某隧道新工作井液氮二次冻结封堵水工程为背景,基于液氮气化时剧烈吸热的原理,提出采用液氮土层冻结技术快速冻结封堵涌水的解决思路。研究在初期盐水冻结壁有缺陷存在条件下运用原有冻结管和新增冻结管液氮封水冻结,冻结帷幕形成和冻结孔布置参数的设计、施工流程以及冻结效果。得到以下结论:1)通过温度数据监测得出测温孔最低温度达-30℃;2)C4测温孔数据表明总体冻结壁发展半径超过原设计的0.54 m;3)C5测温孔数据表明,在距地面9.6m处土层温度已达到-10℃,冻结壁发展半径超过0.70 m;4)裂缝处冻结壁有效厚度达到0.85 m,槽壁内侧温度低于-4℃,且随着深度的加大接缝位置处平均冻结温度降低。

Application of Liquid Nitrogen Freezing Technology in Secondary Water-sealing of Working Shaft of Tunnels

Water sealing by means of rapid liquid nitrogen freezing technology is proposed in the secondary watersealing of the working shaft of a tunnel. Conclusions drawn are as follows ： 1 ） The lowest temperature measured in the monito ring hole is 30 °C. 2） The data measured in C4 temperature monitoring hole show that the developing radius of the frozen wall is 0.54 m larger than that provided in the original design. 3 ） The data measured in C5 temperature monito ring hole show that the temperature of the soil 9.6 m below the ground surface is 10 °C, and the freezing radius is larger than 0.70 m. 4） The effective thickness of the frozen wall at the crack is 0.85 m, the temperature inside the wall is 4 °C, and the average freezing temperature at the connection joint drops as the depth increases.