多工艺联合支护在复杂深基坑中的应用研究

Application of multi-process combined support in deep foundation pit with complex surroundings

为研究多工艺联合支护在复杂深基坑中的应用,以某实际基坑工程为研究背景,结合该基坑开挖深度大、面积大、水位降深大、平面形态复杂、环境要求高、用地空间有限等特点,提出了分区分段的设计方案,北区采用排桩+2道内支撑,南区采用排桩+4道锚索,CSM帷幕止水+大孔径深井排水相结合的治水措施,并利用有限元软件对设计方案进行数值计算。研究结果表明:排桩、内撑与外锚相结合的多工艺联合支护可以弥补单一支护结构的诸多不足,在安全、成本、工期控制方面具有明显优势;排桩+内撑与排桩+外锚的支护形式对周边环境的影响都可以满足相关规范要求,前者影响更小,安全性更好,后者不占用坑内空间,方便施工,可节约后续工期;治水措施对于开挖深度大、水位降深大、排水量大、地基透水性强的“三大一强”地下水防治具有很好的适用性。

In order to study the application of multi-technology combined support in complicated deep foundation pits,In this paper,taking an actual foundation pit project as research background,combined with the characteristics of the foundation pit,including large excavation depth,large area,large drawdown,limited land space,high requirement of environment,and so on.The design scheme of subarea-subsection is put forward,the pile row combined with bi-layered inner support are arranged in the north side,pile row combined with four anchor cables are adopted in the south side for the foundation pits.In the meantime,the use of CSM curtain water stop and large-aperture deep well drainage combined water control measures,and the finite element software is used to carry out numerical calculation on the design scheme.The results show that the multi-technology combined support with pile row,internal bracing and anchor cable can make up for many shortcomings of single support structure,which has obvious advantages in safety,cost and time limit control.The impact of pile row combined with internal bracing and pile row combined with external anchor support on the surrounding environment can meet the requirements of relevant regulations.The former has less impact and better safety,while the latter does not occupy the pit space,which is convenient for construction and can save the subsequent construction period.Water control measures have good applicability for groundwater prevention and control with large excavation depth,large drawdown,large drainage and strong foundation water permeability.The design ideas in this paper can provide references for similar foundation pit projects.