吹填地基无填料振冲密实法质量监控工艺分析

在深厚吹填砂土地基中,采用无填料振冲密实法较为普遍,但吹填砂土的级配和振冲工艺的密实电流、留振时间都会极大影响振冲效果,因此在吹填地基中进行质量监控分析,确定监控流程对确保振冲密实效果极为重要。依托科威特LNGI吹填地基项目分析可得,在吹填过程中应进行监控取样,并可依据可振冲性指数SN和级配曲线分区图对砂料进行初步评估;同时在陆域形成后,基于振前CPT进一步探查可振冲性差砂土的分布范围和深度,并在振冲施工时调整上拔间距和留振时间。经施工试验区分析确定,当选用180 kW振冲器、3. 75 m振冲间距时,在施工过程采用1 m上拔间距,施工过程中实施监控,确保留振时间达到40 s或密实电流大于420 A,满足其一即可达到密实度验收要求。

Quality monitoring and control of vibro-compaction method for hydraulic reclamation

It is very common that the vibro-compaction of ground improvement is applied in deep hydraulic reclamation project.The particle size distribution of barged-in fill sand soil,and densification current and holding time of vibro-compaction process have a great impact on densification achieved.It is very critical to monitor the influence factors to assure the compaction quality.In accordance with the analysis of quality monitoring and control of Kuwait LNGI project,we conclude that the suitability of vibro-compaction for reclamation material can be assessed by suitability number (SN) and graph of range of suitable soil using particle size distribution result in reclamation stage.After reclamation completed,the CPT before compaction should be done and applied to detect the zone of unsuitable material.Accordingly,the densification current and holding time should be adjusted properly to achieve the acceptance criteria.As approved in compaction trail area,when the 180 kW power of vibrator and 3.75 m of spacing is applied,a withdraw with increment of 1 m and compaction with 40 s of holding time or 420 A electric current can be suggested in order to achieve the design densification.