新吹填软土地基复式负压固结技术开发

Technology Development in Newly Dredger Fill Foundation by Composite Negative-pressure Consolidation Method

新吹填土含泥量大、含水率大、渗透性差、零承载力,常规地基处理工法无法开展,地基处理面临诸多困难。针对该问题,提出了复式负压固结技术,该技术包括3道工序:改性真空预压、电渗降水和强夯动力固结。改性真空预压使地基得到初步固结,具备一定强度,为后序工作做准备;电渗降水可有效降低夯前地下水位和土体含水率,并促进夯后超孔隙水压力的消散;电渗降水和强夯动力固结多遍耦合,共同对吹填土进行地基加固。现场开展了复式负压固结技术工艺试验、土性试验和沉降变形监测。结果表明,应用于吹填泥的地基处理,改性真空预压可快速提高承载力,电渗法可迅速降低地下水位,有效避免强夯时"弹簧土"现象的发生,从而提高了最佳夯击能。复式负压固结技术可以有效地应用于新吹填软土地基。

Newly hydraulic fill mud is high-water-content,poor permeability and zero capacity,for which the conventional ground treatment techniques cannot be used and many difficulties will arise.This paper introduces composite negative-pressure consolidation consisting of three working procedures,namely modified vacuum preloading,electro-osmosis dewatering and dynamic consolidation.Modified vacuum preloading reinforces newly hydraulic fill mud to reach a certain intensity and concretion to prepare further treatment.Electro-osmotic dewatering can decrease effectively underground water level and water content,facilitate dissipation of excess pore-water pressure.Hydraulic fill mud is strengthened under the coactions between electro osmosis dewatering and heavy tamping.According to engineering test,soil experiment,monitoring for the settlement deformation,the experiment shows that the electro-osmotic dewatering can also reduce sharp growth of excess pore water pressure during dynamic compaction,and promote dissipation quickly,obviously improving the effectiveness of the technology.avoid the occurrence of ＂spring soil＂ and increase clearly optimum ramming energy.The composite negative-pressure consolidation technology can be effectively used in the foundation newly hydraulic fill mud.