既有大型公共设施改造下紧邻深基坑开挖变形分析*

为探索深基坑开挖与紧邻大型公共设施改造的相互影响，确保施工安全，基于上海体育馆改造及新建地下体育综合体工程，采用有限元软件Plaxis对紧邻深基坑工程大型公共设施“卸载-加载”改造过程进行模拟，详细分析上海体育馆“卸载-加载”改造与紧邻综合体深基坑开挖同时进行对基坑本体及上海体育馆的安全影响，并在此基础上探讨紧邻深基坑工程大型公共设施改造最优工序。结果表明:在基坑开挖至第2道支撑时进行加载改造为最不利工况，且围护结构侧向位移将超过规范允许值，在施工中应严格避免；最优工序为完成第1道支撑后进行卸载改造，完成第2道支撑后进行加载改造。

Deformation analysis of deep foundation pit excavation adjacent to reconstruction of existing large public facility

In order to explore the interaction effect between the deep foundation pit excavation and the reconstruction of adjacent large public facility,thus ensure the construction safety,the finite element software Plaxis was used to simulate the “unloading loading” reconstruction process of a large public facility adjacent to deep foundation pit engineering based on the project of Shanghai gymnasium reconstruction and new underground sports complex construction.The safety influence of the simultaneous Shanghai gymnasium “unloading loading” reconstruction and the deep foundation pit excavation of adjacent complex on the foundation pit itself and Shanghai gymnasium was analyzed in detail,and on this basis,the optimal process of large public facility reconstruction adjacent to deep foundation pit engineering was discussed.The results showed that the most unfavorable condition was to carry out the loading reconstruction when the foundation pit was excavating to the second support,and the lateral displacement of retaining structure would exceed the allowable value of the code,which should be strictly avoided during the construction.The optimal construction process was to carry out the unloading reconstruction when finishing the first support,and carry out the loading reconstruction when finishing the second support.