强制搅拌斜向支撑桩在软土基坑中的应用

Application of forced mixing inclined support pile in soft-soil foundation pit

在开挖面积大但深度一般的基坑工程中,斜向支撑因其具有挖土方便、换撑工况相对独立、施工周期短的特点而被广泛应用。根据斜向支撑的支撑点不同,可以分为撑在基础底板、支撑桩与地基土三类。本文介绍了一种支撑点位于地基土中的斜向支撑体系在杭州某软土基坑中的应用。该支护体系由钢格构、预制方桩、强制搅拌体以及扩大底部组成。阐述了强制搅拌体斜向支撑桩的设计要点与施工工艺,并从经济性、安全性、施工可操作性等方面与传统斜向支撑进行了对比。相较于传统斜向支撑,强制搅拌斜向支撑桩具有施工工序少、可小净距施工、适用于多种地层、可控制变形的特点。施工现场反馈与监控量测结果表明,该支护形式可以充分发挥排桩、斜向支撑、桩间土体的协同作用,有效控制开挖过程中引起的变形,可为类似软土地区基坑工程的支护设计提供借鉴与参考。

In foundation pit projects with a significant excavation area but moderate depth,inclined bracing finds extensive application due to its advantageous attributes,including convenient excavation,relatively independent support changing conditions and short construction period.In accordance with the location of the inclined support,it can be categorized into three distinct types:support on the base plate,support on support piles and support on foundation soil.This work introduces the application of an inclined support supported in the foundation soil in a soft-soil foundation pit in Hangzhou.The support system consists of steel lattice structure,prefabricated square piles,forced stirring body and enlarged bottom.The design points and construction technology of the forced mixing inclined support pile are expounded in detail.Furthermore,it is compared with the traditional inclined support from the aspects of economy,safety and construction operability.In contrast to conventional inclined support,the forced mixing support pile offers advantages such as a streamlined construction process,suitability for use at close proximity,adaptability to various geological strata,and controlled deformation.Based on feedback and construction site monitoring results,this support approach optimally leverages the synergies among piles,inclined support,and the soil between them,effectively managing the deformation arising from excavation.This research can serve as a valuable reference for foundation pit support design in similar soft-soil regions within foundation pit engineering.