地铁深基坑钢支撑施工节点优化与轴力控制

Node Optimization and Axial Force Control of Steel Supporting in Metro Deep Foundation Pit

针对地铁深基坑钢支撑施工过程中端头节点复杂、采用轴力计作监测存在失稳风险、普通钢支撑轴力的施加损失严重不利于围护变形控制和伺服与普通钢支撑分界处地下连续墙接头两侧变形不均匀等问题,以南京地铁5号线虹桥站基坑工程为例,通过对地下连续墙预埋钢板及防坠落措施作优化、采用现场校核过的表面应变计监测轴力、轴力分阶段施加并适当提高最终控制值、伺服与普通钢支撑分界处增设围檩等措施,达到施工过程中安全有保证、质量可控制、现场易操作的效果,可为类似的钢支撑施工提供经验和参考。

During the construction process of steel supporting for deep foundation pit of subway,there’re problems of the complex end joints,the risk of instability caused by axial force meter as monitoring,the serious loss of axial force of ordinary steel supporting is disadvantageous in controlling enclosure deformation,and the uneven deformation on both sides of the diaphragm wall joints at the boundary between servo and ordinary steel supporting.Taking the foundation pit engineering of Hongqiao Station of Nanjing Metro Line 5 as an example,the measures of embedded steel plate of diaphragm wall and anti-fall are optimized,the surface strain gauge checked on site is used to monitor the axial force,the axial force is applied in stages and the final control value is properly improved,and enclosing purlins are added at the boundary between servo and ordinary steel support.Through the above measures,the safety of the construction process is guaranteed,the quality controlled and easy to operate on site.It can provide experience and reference for similar steel supporting construction.