南宁某地铁隧道风井围护结构设计优化与评价

传统设计方法在设计深基坑围护时通常采用断面计算,无法考虑结构整体作用,忽略了结构围岩工作变形,容易导致设计结构断面特别大、围护结构地连墙尺寸厚、混凝土支撑断面大等现象,造成极大浪费。以南宁市轨道交通某区间风机房竖井围护工程为依托,采用FLAC 3D软件完成数值模拟建模,考虑了结构整体性以及结构与围岩的共同变形条件,对工程采用的地下连续墙与支撑支护体系方案进行了优化,连续墙厚减少33.33%,纵向受力钢筋面积减少22.36%。在此基础上,进一步对优化方案的安全性与经济性进行系统评价。结果表明:优化方案的各工程参数均能很好地满足规范要求,相比传统设计方案,优化方案在现有总施工造价费用上可减少12.37%; 研究结论具有显著的工程经济意义,可为类似工程深基坑围护结构的设计及优化提供参考。

Design Optimization and Evaluation of Air Shaft Enclosure Structure of a Subway Tunnel in Nanning

The enclosure structure of deep foundation pit in traditional design methods is usually calculated by section, so the overall action of the structure can not be considered, and the working deformation of the surrounding rock of the structure is ignored. It is easy to cause such phenomena as extremely large section of design structure, thick size of ground connecting wall of enclosure structure, large section of concrete support, and cause great waste. To solve these problems, based on the fan room shaft enclosure project in a section of Nanning rail transit, FLAC 3D software was used to complete the numerical simulation modeling. Considering the structural integrity and the common deformation conditions of structure and surrounding rock, the scheme of diaphragm wall and support system used in the project was optimized. The thickness of diaphragm wall was reduced by 33.33%, and the area of longitudinal stressed reinforcement was reduced by 22.36%. On the basis, the safety and economy of the optimization scheme were further systematically evaluated. The results show that the engineering parameters of the optimization scheme can well meet the specification requirements. Compared with the traditional design scheme, the optimization scheme can reduce the existing total construction cost by 12.37%. The research conclusion has significant engineering economic significance, and can provide reference for the design and optimization of deep foundation pit retaining structure in similar projects.