软土地区交通重载下条形深基坑支护设计

Supporting Design of Strip-type Deep Foundation Pit under Heavy Traffic in Soft Soil Area

借助上海市隆昌路下立交条形深基坑工程,从围护选型、支护结构设计、验算和实测等方面总结了交通重载下的支护设计重点和难点。结果表明:从安全性和经济性考虑,10 m以内基坑采用型钢水泥土搅拌墙较合理;虽然软件验算结果表明围护各项控制指标均满足规范要求,但实际围护变形量明显偏大,分析原因主要为支撑不及时、降水效果不佳、周边交通重载持续作用、围护刚度偏弱等。为此提出建议:应加强现场施工管理,并针对此类基坑的支护进行加强设计,如部分深基坑可考虑型钢密插以提高围护刚度;地基加固抽条间距加密,加固深度加深;钢支撑间距加密至3~3.5 m。

Based on the strip-type deep foundation pit project of interchange under Longchang Road in Shanghai, the key points and difficulties of supporting design under heavy traffic are summarized from the selection of enclosure, design of supporting structure, checking calculation and actual measurement. The results show that considering the safety and economy, it is more reasonable to use the section steel cement-soil mixing wall for foundation pit within 10 m. The checking results of the software shows that all control indexes of enclosure meet the specification requirements, but the actual enclosure deformation is obviously too large. The analysis causes are the untimely support, poor precipitation effect, continuous heavy load of surrounding traffic and weak enclosure stiffness. Therefore, the proposal is to strengthen the management of site construction. And the design of supporting for this kind of foundation pit is strengthened, i.e. some deep foundation pits are considered to insert the section steel densely to improve the enclosure stiffness. The strip spacing of foundation reinforcement is densified. The reinforcement depth is deepened. The spacing of steel supports is densified to 3 ~ 3.5 m.