以郑州机场至许昌市域郑州段某区间富水砂层联络通道冻结加固法施工场地为工程实例,基于考虑流热耦合作用的温度场和渗流场控制方程,运用COMSOL软件构建了联络通道进深2.0 m横截面的二维模型,采用Logistic函数建立实测盐水回路温度拟合曲线,将拟合函数作为冻结孔的管壁温度边界条件,通过数值计算得到了联络通道冻结过程中的温度场云图和温度变化曲线。通过比对数值结果与现场实测数据验证了数值模型的准确性和合理性,并进一步研究了地下水流速、冻结管间距、冻结管直径、初始地温等因素对温度场发展的影响。引入单因素灵敏度分析法,求解了各因素对冻结壁交圈时间影响的灵敏度,确定了各因素影响的大小排序,结果表明:当地下水流速较大时,减小冻结管间距是削弱地下水流速对冻结温度场影响的最佳选择;当初始地温较高时,通过增大冻结管直径或减小冻结管间距都能提高冻结效率。
The construction site of the freezing reinforcement method for the connecting channel in sand layer with rich water of one section in Zhengzhou section from Zhengzhou airport to Xuchang city was taken as an engineering example, the temperature field and seepage field control equations of fluid thermal coupling theory were adopted, a two-dimensional numerical calculation model for the cross-section of the connection channel with 2.0 m depth was constructed with COMSOL software, the fitting measured temperature curve of the salt water circuit was built with Logistic function, the fitted equation was used as an interpolation function to define the temperature of the freezing tube, temperature field nephogram and temperature curve during the freezing process of connecting channel were obtained through numerical calculation, the accuracy and rationality of the numerical model were verified by comparing the numerical results with on-site measured data, and the influences of the factors of groundwater flow rate, freezing tube spacing, freezing tube diameter, and initial ground temperature on the temperature field development were further studied. The single factor sensitivity analysis method is introduced, the sensitivity of each factor on the freezing wall intersection time was solved, the magnitude order of the influence of various factors was determined, the sensitivities were compared and it was found that: to reduced the spacing between freezing pipes is the best choice to weaken the influence of groundwater flow rate on the freezing temperature field when the groundwater flow rate is high; to increase the diameter of the freezing tube or reduce the spacing between the freezing tubes can improve the freezing efficiency when the initial ground temperature is high.
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