排水方法对强夯加固饱和粉土效果的影响  

Influence of Drainage Method on Improvement Effect of Dynamic Compaction for Saturated Silt

作　　者：楼晓明 LOU Xiaoming(Shanghai Geoharbour Construction Group Co.,Ltd.,Shanghai200434,China)

机构地区：[1]上海港湾基础建设(集团)股份有限公司,上海200434

出　　处：《施工技术（中英文）》2024年第11期56-61,共6页Construction Technology

摘　　要：饱和粉土为介于砂土与黏性土之间的半渗透性土,强夯加固时通常需要辅助排水措施以提升处理效果,排水方法主要有塑料排水板法和真空排水法,因此需关注不同排水措施对强夯加固效果的影响。某项目位于海边养殖场,原地基上部为3~5m厚的饱和粉土,承载力低、可液化,同时原地面标高低,采用风化开山土回填,因此地基处理时包括上述2层土,回填土含水率低、性质相对较好,地基处理重点是饱和粉土层。不同功能区由不同单位分别采用强夯法联合真空排水和塑料排水板、水平排水垫层进行试验,对比排水和强夯施工参数、施工沉降、加固前后粉土层物理力学指标和原位试验指标变化情况。结果表明:强夯联合真空排水法未在回填土上设置水平排水垫层,施工沉降更大,粉土物理力学指标和原位试验指标改善更明显;强夯联合塑料排水板法在回填土上设置了水平排水垫层,回填土中的细颗粒土被塑料排水板排出的水浸湿、软化,同时增加了塑料排水板内的水头高度,影响了排水固结效果。Saturated silt is a semi permeable soil between sand and clay.During dynamic compaction reinforcement,auxiliary drainage measures are usually needed to improve the treatment effect.There are mainly two drainage methods:plastic drainage boards and vacuum drainage.Therefore,it is necessary to pay attention to the impact of different drainage measures on the reinforcement effect of dynamic compaction.A certain project is located at a seaside aquaculture farm.The upper part of the original foundation is 3~5m thick saturated silt,with low bearing capacity and liquefiability.At the same time,the original ground level is high and low,and weathered mountain soil is used for backfilling.Therefore,the depth of foundation treatment includes the above two layers of soil,but the backfill soil has low moisture content and relatively better properties.The focus of foundation treatment is on the saturated silt layer.Different functional areas were tested by different units using the dynamic compaction method combined with vacuum drainage,plastic drainage board,and horizontal drainage cushion layer.The changes in drainage and dynamic compaction construction parameters,construction settlement,physical and mechanical indicators of the silt layer before and after reinforcement,and in-situ test indicators were compared through two methods.The results showed that the dynamic compaction combined with vacuum drainage method did not set a horizontal drainage cushion layer on the backfill soil,resulting in greater construction settlement and more significant improvement in the physical and mechanical indicators and in-situ test indicators of the silt;The method of dynamic compaction combined with plastic drainage board sets a horizontal drainage cushion layer on the backfill soil.The fine particle soil in the backfill soil is soaked and softened by the water discharged by the plastic drainage board,while increasing the water head height inside the plastic drainage board,which affects the drainage consolidation effect.

关 键 词：饱和粉土 强夯 真空排水 高真空击密法 

分 类 号：TU47[建筑科学—结构工程]