盾构始发端垂直冻结温度场数值分析与现场实测

太原地铁双塔西街站-大南门站区间盾构始发端采用垂直冻结法加固技术。由于盾构始发的特殊性,冻结帷幕的有效厚度能不能保证,是关系到土体加固是否安全的前提。通过建立三维数值模型对该工程冻结帷幕温度场随时间的发展规律展开研究,动态模拟冻结帷幕的演化过程,并且现场实时监测记录了冻结帷幕的温度变化和盐水温度随时间的变化情况,分析了在同一深度处各测温孔测点温度随时间的变化规律,计算了冻结帷幕厚度与冻结帷幕平均温度,验证了盾构是否具备始发的条件。结果表明:实测温度值和数值计算温度值总体趋势基本一致;采用垂直冻结方式、三排冻结管冻结施工的方案是合理的;用数值模型来模拟冻结帷幕温度场的变化过程是可行的。

Numerical Analysis and Field Measurement of Vertical Freezing Temperature Field at the Beginning of Shield Tunneling

The vertical freezing method is adopted to reinforce the shield tunneling between the Shuangta West Street station to the Da Nanmen station. Because of the particularity of shield initiation, whether the effective thickness of freezing curtain can be guaranteed is the precondition for the safety of portal reinforcement. In this paper, through the establishment of three dimensional numerical model for the freezing engineering curtain researches on the law of development of temperature field with time, the dynamic simulation of the frozen soil evolution process, and the real-time monitoring recorded the temperature of freezing curtain and brine temperature changes with time, the analysis of the depth in the same place the thermometer hole measuring point temperature variation law with time, to calculate the thickness of frozen wall with the average temperature of frozen wall, verify whether the shield with the initial conditions. The results show that the overall trend of the measured temperature value and the numerical calculation temperature value is basically the same, the scheme of vertical freezing method and three-row frozen pipe freezing construction is reasonable, and it is feasible to use the numerical model to simulate the change process of frozen soil curtain temperature field.