孔内强夯碎石桩加固软土地基的变形特性分析  

Deformation characteristics of reinforcement of soft soil foundation with dynamic compaction gravel pile in hole

作　　者：伍翔飞 曾华健 嵇汉卿 刘雪珠 祝思明 郑海波 WU Xiang-fei;ZENG Hua-jian;JI Han-qing;LIU Xue-zhu;ZHU Si-ming;ZHENG Hai-bo(Jiangsu Geotechnical Engineering Company,Nanjing 210018,Jiangsu,China;Shenzhen Sukan Geotechnical Engineering Co.,Ltd.,Shenzhen 518100,Guangdong,China)

机构地区：[1]江苏省岩土工程公司,江苏南京210018 [2]深圳市苏勘岩土工程有限公司,广东深圳518100

出　　处：《地基处理》2023年第S02期69-74,83,共7页Journal of Ground Improvement

摘　　要：本文基于某物流仓储项目软土地基处理工程,通过室内试验及原位测试,研究碎石桩处理前后软土层的物理力学指标变化及处理后复合地基承载力情况。建立单桩碎石桩复合地基分析模型,采用有限元方法,对施工与使用等附加荷载作用下碎石桩处理前后的复合地基变形特性及孔压消散情况进行了计算,在此基础上,进一步分析了不同桩径、桩长及垫层厚度对碎石桩复合地基沉降变形与孔压消散特性的影响。结果表明:软土地基经碎石桩处理后,原天然状态下的软土物理力学指标均有所提高,其中软土状态由天然状态下的流塑状态变为可塑状态,含水率降低约22.3%;与天然软土地基相比,碎石桩复合地基处理后,工后沉降及固结时间可减小约50%;为平衡成本及处理质量,碎石桩面积置换率在0.22左右,桩端应穿过软土层底不少于1 m较为合适,且垫层厚度不宜过大,相关结论可为类似工程提供参考。Employing a logistics warehousing project as a case study for soft soil foundation treatment,this paper investigated alterations in the physical and mechanical properties of the soft soil stratum pre and post gravel pile treatment,as well as the bearing capacity of the treated composite foundation.This investigation was conducted through a combination of indoor experiments and in-situ testing.An analytical model was developed for a composite foundation consisting of single gravel piles.The finite element method was employed to capture the deformation behaviour and dissipation of pore pressure within the composite foundation both pre and post gravel pile treatment,considering superloading.An in-depth analysis was conducted to assess the influence of pile diameters,lengths,and cushion thicknesses on the settlement deformation and pore pressure dissipation characteristics of the gravel pile composite foundation.The findings reveal significant improvements in the physical and mechanical properties of the soft soil following gravel pile treatment compared to its original natural state.Specifically,the plasticity of soil transitioned from a flow plastic state to a plastic state,accompanied by a reduction in water content by approximately 22.3%.Moreover,in comparison to a natural soft soil foundation,the post-construction settlement and consolidation period of the gravel pile composite foundation can be halved after treatment.To strike a balance between cost and treatment efficacy,it is recommended that the replacement rate of the gravel pile area be maintained at approximately 0.22.Additionally,it is advisable for the pile end to penetrate the bottom of the soft soil layer by no less than 1 m,and caution should be exercised in controlling the thickness of the cushion layer.These relevant conclusions can provide valuable reference for similar projects.

关 键 词：孔内强夯碎石桩 软土地基 变形特性 数值分析 软土固结 

分 类 号：TU472[建筑科学—结构工程]