直线形单排管冻土帷幕平均温度计算

在人工地层冻结工程中,平均温度是评价冻土帷幕状态,进行冻土帷幕力学性能分析的基本参数,本文研究单排管冻结形成的冻土帷幕的平均温度计算。基于单排管冻结稳态温度场解析解,直接对温度场表达式进行积分运算,运用分部积分法和积分中值定理,得到了单排管冻结平均温度计算公式,根据工程中的实际参数取值进行了公式的简化。考虑到温度场解析解在冻结管区域的不适用,采用相同的积分策略求解冻结管区域对平均温度计算的影响,进行了平均温度计算公式的修正。使用A NSYS进行了单排管冻结的热学稳态数值模拟与平均温度计算公式的结果进行比对,考察管间距l=0. 4,0.6,0.8,1.0,1.2,1.4 m,相对厚度ξ/l=0. 5,0.6,0. 7,0. 8,1.0,1.5共6种冻结发展状态,根据试验报告进行土质参数取值,冻结参数为工程中常用取值。对比计算结果显示,公式计算与数值计算的结果较为吻合。当相对厚度大于0.5时,随着冻土厚度的发展(相对厚度的增大),理论计算结果与数值计算结果的差值迅速减小到0.5以内,当相对厚度大于0.6时,差值小于0.2℃当相对厚度为1及以上时,差值小于0.1℃。通过数值模拟验证了平均温度计算公式的准确性,也说明公式简化和修正的合理性,公式计算的误差满足工程应用的要求。

Calculation of average temperature of frozen soil wall by single row piped freezing

In the artificial ground freezing project,the average temperature is the basic parameter for evaluating the frozen soil curtain state and the mechanical analysis of the frozen soil curtain.The average temperature calculation of the frozen soil curtain formed by the single row pipe freezing is studied in this paper.Based on the analytical solution of the steady state temperature field of a single row pipe freezing,the integral calculation of the temperature is directly performed.Using the partial integral method and the integral median theorem,the calculation formula of the average temperature of the single row tube freezing is obtained,and the formula is simplified according to the actual parameter values in the project.Considering that the temperature field analytical solution is not applicable in the frozen pipe area,the same integral strategy is used to solve the influence of the frozen pipe area on the average temperature calculation,and the average temperature calculation formula is corrected.The results of the average temperature calculation formula were compared with the results of the thermal steady state numerical simulation of the single row pipe freezing using ANSYS.The pipe spacing l=0.4,0.6,0.8,1.0,1.2,1.4 m,and there are six kinds of frozen development states with relative thickness ξ/l=0.5,0.6,0.7,0.8,1.0 and 1.5.The values of soil parameters are taken according to the test report and the freezing parameters are commonly used in engineering.The comparison calculation results show that the formula calculation is in good agreement with the numerical calculation results.When the relative thickness is over more than 05,the difference between the formula calculation result and the numerical calculation result is rapidly reduced to within 05 ℃ with the development of the frozen soil thickness (relative thickness increase).When the relative thickness is greater than 0.6,the difference between the results is less than 02 ℃.When the relative thickness is 1 or greater,the difference is less than 01 ℃.The accuracy of the average temperature calculation formula is verified by numerical simulation,and the rationality of the formula simplification and correction is also explained.The error calculated by the formula satisfies the requirements of engineering application.