盾构隧道端头半球形冻结壁温度场发展规律研究

摘要

对盾构隧道端头半球形冻结壁加固结构作简单介绍,运用有限元软件数值建模分析了半球形冻结壁温度场的发展规律.主要得出:半球形冻结壁是一种高效节能的盾构隧道端头冻结加固方式;冻结初期,冻土帷幕是以冻结管为中心呈柱状向外扩展,到冻结40d时,可形成厚度约为1.8m的封闭半球形壳体冻土帷幕;可采用增加环形冻结管对数、延长冻结时间和降低盐水温度来将半球形冻结壁冻实;半球形冻结壁纵向(X轴)冻结影响范围约为5m.%A brief introduction was given on the reinforcement structure of hemispherical frozen wall at the end of shield tunnel in this paper.The method of Finite Element Numerical Simulation was used to analyze the development of temperature field of the hemispherical frozen wall.The results showed that the hemispherical freeze wall is an energy-efficient freezing reinforcement way for end of shield tunnel.In the initial freezing stage,frozen soil curtain centered at the frozen pipes and extended outwards in a pillar shape.A thickness of about 1.8m closed hemispherical shell frozen soil curtain would be formed when it experienced 40 days freezing.It could uniformly freeze the hemispherical frozen wall to improve the frozen effects by increasing the number of pairs of freezing pipes,prolonging freezing time and lowering the brine temperature.The effect radius of a hemispherical frozen wall was about 5 m along the longitudinal(X-axis)direction.