地铁施工近邻桥基加固效果三维数值分析

结合北京地铁10号线国贸站西北风道施工对邻近桥基影响的工程问题,针对拟定的不同桥基加固方案, 在对施工过程进行三维动态数值模拟的同时,重点分析了施工过程中桥基的变形和受力性态以及桩土相互作用机理,并将部分计算结果与量测结果进行了比较。研究表明,桩基托换能够有效地减少施工期间桥基的沉降, 桥基沉降能够满足其控制标准要求;通过支撑减载以及在短桩底部进行局部注浆加固不能明显减少施工造成的桥基沉降。其研究成果能够为该工程与类似工程施工提供指导和参考作用。

RESEARCH ON THE REINFORCING EFFECT OF ADJACENT SHORT PILE BRIDGE FOUNDATION IN METRO STATION CONSTRUCTION

Combined with the Guomao station of Beijing metro line 10, by means of ABAQUS software, in order to protect the safety of pile foundation around the building metro station engineering, several main consolidation projects are concerned about, based on different reinforcing projects, 3 -D FEM numerical models used to simulation reinforcing effect are built respectively, construction process and construction effect on the adjacent short-pile foundation of Guomao bridge are simulated and the deformation and force character of pile foundation as well as the interaction mechanism of pile-soil simulated by means of surface to surface contact element type of ABAQUS software are studied. The partial results acquired by simulation and measure are nearly consistent by compare, such as surface settlement maximal value by simulation is 7.5 mm and 13.10 mm and its maximal value by measure is 13.46 mm and bridge foundation settlement value by simulation is 7.5 mm and its measure value is 7.32 mm, and a mass of harvest is achieved. The conclusions are reached that pile settlement can be effectively decreased by underpinned pile, such as its settlement for 22.3 mm without reinforcing measure and its settlement less than 29 mm with reinforcing measure and pile settlement less than control criterion for the latter, and that there is almost no effect on reducing pile foundation settlement induced by construction for the latter, and that there is almost no effect on reducing pile foundation settlement induced by construction by means of bracket used to uninstall and grouting reinforcement around pile bottom, and that based on economy and rationality, the project of case-2 is recommended for similar engineering construction. It was proved on real engineering condition that bridge foundation settlement value is 7.5 mmat the end of the S1 construction stage, bridge foundation settlement value is 10.8 mm at the end of the S2 construction stage, bridge foundation settlement value is 12.2 mm at the end of the S2 construction stage, bridge foundation settlement value is 14.8 mm at the end of the S4 construction stage, bridge foundation settlement value is 17.7 mm at the end of the S5 construction stage. And also it was proved that for the case-1 maximal resistance of short pile is 3682 kPa and its negative friction force whose maximal value is 1.2 kPa is relatively small, and that for case-2 maximal resistance of short pile is 779 kPa and its negative friction force whose maximal value is 0.2 kPa is relatively smaller and maximal resistance of long pile is 6813 kPa and its negative friction force whose maximal value is 0.6 kPa is relatively smaller. The basis and guidance are provided for succedent and similar engineering construction.