复杂边界条件下的基坑支护设计实践

Practice of Foundation Pit Support Design under Complex Boundary Conditions

文章依托苏州地区某深基坑工程,阐述了在周边环境、挖深等复杂边界条件下,采用钻孔灌注桩结合内支撑体系、多级自稳放坡结合重力式挡土墙、地下连续墙结合多道内支撑的不同围护形式相联合的总体围护方案,并采取分区、分坑实施技术。结果表明:变形协调、刚度变化对多种联合支护形式的影响需重点考虑,不同围护体系水平向变形差异大,衔接处应加强处理。开挖面积大、长条形基坑采取全封闭式止水帷幕,后期施工区域因时效止水效果不理想。帷幕的止水效果受浅层填土的组成成分影响大,清障需彻底。

On the basic of a deep foundation pit in Suzhou area,explains the overall retaining scheme of bored pile with internal bracing system,multi-level self-stabilization slope with gravity retaining wall,diaphragm wall combined with multi internal support under the different environment and depths.Construct the deep foundation pit in the form of zoning and dividing.The results showed the effects of deformation and stiffness on the combined supporting should be considered.The joint between different foundation pit system should be handled.For the rectangular and deep excavation,the water-stop effect of mixing pile in later stage of construction is not ideal.The water-stop effect of mixing pile is affected by the filling layer composition.