基坑开挖卸荷引起下卧隧道隆起的计算方法

Calculation of Tunnel Heaving due to Unloading of Pit Excavation

目前越来越多的基坑工程位于已建地铁隧道之上,近距离基坑开挖土体卸荷势必引起隧道的隆起,因此如何预测隧道变形、确保隧道使用安全日趋重要。本文以上海东方路下立交工程为背景,由Mindlin经典理论解推导出由于开挖卸荷引起隧道结构的附加应力,进而通过弹性地基梁理论求算隧道隆起的定量计算方法。并根据此方法求得隧道最大隆起值,与实测结果对比分析,得出结论。

At present, more and more pit excavations lie over the built Metro tunnels. The near unloading certainly will lead to heaving of underlying tunnels. Therefore, how to predict tunnel deformations to insure its working safety becomes very important. Based on Dongfang Road Underground Crossing project in Shanghai, the additional stress in the tunnel lining due to excavation of foundation pit can be deduced by Mindlin theory. Then, a method to calculate the heaving of tunnel can be deduced by elastic foundation beam theory and the calculated maximum heaving is compared with monitoring data. From the analysis, some conclusions can be drawn.