滨海回填区深基坑支护技术分析

Analysis of deep and large foundation pit support technology under coastal backfill area

滨海回填区具有地质环境复杂、软弱层较厚、地下水位高等带来的基坑开挖难度大的特点,寻找一种既安全又经济的基坑支护方式为滨海回填区基坑支护设计的一大难题。文章以深圳机场站前综合配套保障用房项目基坑支护工程为例,根据不同区域的地质情况以及后续施工工艺要求,分别采用“锚桩+三轴搅拌桩”、“双排灌注桩+三轴搅拌桩”、“复合土钉墙”3种支护方式,开挖过程中采用现场监测以及数值模型分析坑支护结构的水平与竖向位移值均小于预警值。研究结果表明:滨海回填区有针对性的按区域分段选择支护技术,可以将支护结构的变形控制在限值范围内,满足支护结构安全,且具有较好的经济性,可为滨海回填区深大基坑的开挖提供一定的指导和借鉴。

The coastal backfill area has the characteristics of complex geological environment,thick soft layer and high groundwater level,which makes it difficult to excavate the foundation pit.Finding a safe and economical foundation pit support method is a major problem in the design of foundation pit support in coastal backfill area.Taking the foundation pit support project of Shenzhen Airport Station Comprehensive Supporting Housing Project as an example,according to the geological conditions of different regions and the requirements of subsequent construction technology,three support methods of‘anchor pile+three-axis mixing pile',‘double-row bored pile+three-axis mixing pile'and‘composite soil nailing wall'are adopted respectively.In the process of excavation,the horizontal and vertical displacement values of the pit support structure are less than the early warning value by field monitoring and numerical model analysis.The research results show that the targeted selection of support technology according to regional segmentation in the coastal backfill area can control the deformation of the support structure within the limit range,meet the safety of the support structure,and have good economy,which can provide some guidance and reference for the excavation of deep and large foundation pits in the coastal backfill area.