逆做法施工坑底回弹对支护结构的影响  

Effect of Foundation Bottom Heave due to Excavation on Supporting System in Top-Down Method

作　　者：刘畅[1] 郑刚[1] 张书鸳[1] 

机构地区：[1]天津大学建筑工程学院,天津300072

出　　处：《天津大学学报》2007年第8期995-1001,共7页Journal of Tianjin University(Science and Technology)

摘　　要：在天津开发区软土中设计了第1个采用盖挖逆做法的深基坑.盖挖逆做法有安全、基坑变形对环境影响小等特点.但是,逆做法施工时基坑回弹常引起结构不均匀回弹,回弹在支撑柱中引起附加轴力,此时若支撑柱失稳则导致水平楼盖坍塌;对有支撑柱的内支撑基坑,支撑系统因回弹引起附加弯矩,梁板在过大的附加弯矩作用下易开裂,为此,必须正确计算基坑开挖中的回弹量及其影响.为此采用有限元分析结合实测研究了逆做法施工中的基坑回弹问题,探讨了其对楼板和支撑柱回弹的影响,发现最大的竖向差异沉降发生在围护结构与紧邻围护结构的第1根支撑柱之间,并且楼板与围护结构刚接时,基坑回弹在楼板边缘引起较大的附加弯矩,节点处需要加强.The first deep foundation pit in Tianjin economic-technological develope area （TEDA） soft soil was designed by top-down method. The method has such advantages as high reliability and less impact on the envi- ronment due to small ground movement. But the foundation pit heave often produces adverse effect on the supporting system, for example, it can bring about additional axial force of the solider beam and additional bending moment of the supporting system. The floor slab will collapse if the solider beam loses stability, while the beam and floor slab will crack due to the excessive additional bending moment. Because of the above reasons it is important to predict heave and its effect on the supporting system. By FEM and field measurement, the foundation pit bottom heave and its effect on the floor slab and solider beam were studied. Results showed that the maximal vertical displacement occurred between the retaining structure and the first solider beam away from the retaining structure, and additional bending moment of floor slab was greater when the retaining structure and floor slab were of rigid connection, thus the connection should be strengthened.

关 键 词：深基坑 逆做法 回弹 变形 

分 类 号：TU[建筑科学]