滨海道路吹填软基增压式真空预压试验研究

Experimental Study on Air-boosted Vacuum Preloading of the Hydraulic Filled Soft Foundation of Coastal Roads

为研究无砂增压式真空预压对含砂量较高的吹填土软基的加固效果,以闽南沿海某道路工程为依托开展原位试验研究,在监测检测基础上,对膜下真空度和孔隙水压力变化、地基固结沉降特点及加固前后土的物理力学性质指标进行了分析,并就土体增压时机问题进行了讨论。结果表明无砂增压式真空预压技术对含砂量较高的吹填土地基具有十分良好的加固效果,土层负孔隙水压力的增长与膜下真空度的增长同步,土层的固结沉降滞后于负孔压和膜下真空度的增长,第60d土层固结度达到70%~80%,可缩短工期。注气增压效果不佳,建议对注气增压固结机理和增压时机进一步开展理论和试验研究。

In order to study the reinforcement effect of the air-boosted vacuum preloading without sands on the soft foundation dredger-filled with high content of sands,an in-situ test was carried out based on a road project along the southern coast of Fujian.On the basis of monitoring and testing,the changes in the vacuum degree under the membrane,pore water pressure,the characteristics of foundation consolidation and settlement and the physical and mechanical properties of the soil before and after reinforcement were analyzed,and the opportune moment of soil pressurization was discussed.The results showed as follows.The technique of air-boosted vacuum preloading without sands had a very good reinforcement effect on the soft foundation dredger-filled with high content of sands.The negative pore water pressure of the soil layer increased with the increase of the vacuum degree under the membrane.The consolidation settlement lagged behind the growth of negative pore pressure and vacuum degree under the membrane,and the consolidation degree of the soil layer reached 70%~80%on the 60th day,which could shorten the construction period.However the effect of gas injection for pressurization was not good.It is recommended to further carry out theoretical and experimental researches on the mechanism of gas injection for pressurization and the opportune moment of pressurization.