地连墙影响下多排管冻结壁平均温度计算方法

Average Temperature Calculation Methods for Straight Multi-row-pipe Frozen Soil Wall Considering the Influence of Diaphragm Wall

地铁隧道盾构始发接收端头常使用垂直冻结法加固,冻结壁平均温度是评价其地铁隧道端头冻结加固效果的重要指标。基于南京地铁盾构端头垂直冻结法加固工程,考虑地连墙热辐射作用,给出了积极冻结期结束时直线双排管和多排管冻结壁平均温度计算经验公式。采用数值模拟的方法,拟合得到平均温度计算经验公式,发现靠近地下连续墙一侧冻结壁温度比土体内侧高0.8℃,故已有平均温度公式计算结果偏于危险。将推导的双排管平均温度经验公式的计算值与巴霍尔金解析解比较,结果表明两者相对误差小于2.8%;在此基础上,把双排管计算公式分段组合,得到了适合多排管的平均温度计算公式,经验证该公式与数值模拟结果的相对误差小于1.7%,两个公式均具有足够的精度,满足工程应用要求。

Originating receiver of shield subway tunnel is usually reinforced by vertical freezing methods,the average temperature of frozen wall is an important index to evaluate its effect.Based on vertical freezing projects of Nanjing metro,empirical formulas for calculating the average temperature of double and multi-row-pipe frozen soil wall at the end of the active freezing period are given.The effect of thermal radiation of diaphragm wall is taken into consideration.The empirical formula is obtained from numerical simulation.It is found that the temperature of frozen soil wall on one side close to the diaphragm wall is 0.8℃higher than that inside soil.It may be dangerous to use the existing formulas.Compared the calculated value which is deduced from the formula for calculating average temperature of double-row-pipe with Bakholdin analytical solution,the result shows that the relative error between them is less than 2.8%;On the basis,the formula for calculating average temperature of multi-row-pipe can be obtained by the multi-segment of formula for double-row-pipe.It is proved that the relative error between the formula and the numerical simulation result is less than 1.7%,two formulas have sufficient accuracy to meet the requirement of engineering application.