Experimental Study On Treatment Of Deep And Thick Soft Foundation By Electro-osmosis Combined With Vacuum Preloading Method

There are a large number of soft soil foundations distributed in the southeast coastal areas of China.These foundations often have characteristics of poor permeability,high compressibility,and poor bearing capacity.The traditional foundation treatment methods took a long time to drain and consolidate,and may even fail to achieve the expected result when dealing with thick soft soil layers.In recent years,the combined application of electro-osmosis technology and vacuum preloading method has become a new soft ground treatment method—electro-osmosis combined with vacuum preloading method.This method has its unique advantages in the field of deep soft ground treatment,and has a very promising application prospect.At present,the technology of electroosmotic vacuum combined with preloading method is still immature,and there are few engineering application cases.Previous studies have mainly focused on laboratory experiments and the electrodes used were mostly metal electrodes.The few engineering applications were mostly for shallow soft soil treatment.In order to explore the effect of this method on the treatment of deep and thick soft soil,considering the future development trend,this paper uses a new type of electro-kinetic geosynthetics(EKG)as the electrode.Based on actual engineering,a field experimental study was conducted on the treatment of deep and thick soft soil foundations using the electro-osmosis combined with vacuum preloading method.The paper has demonstrated such following conclusions through the analysis of monitoring and testing data of field comparative test,and the analysis of the previous engineering data:(1)Electro-osmosis combined with vacuum preloading method can effectively improve the soil shear strength and soil physical and mechanical indicators within the electro-osmotic depth range.The growth rate of shear strength in the electroosmotic depth range of the test area is about 39% higher than that of the corresponding depth range in the comparison area.(2)Electro-osmosis combined with vacuum preloading method can promote the treatment of deeper soil to a certain extent,and solve the problem that the treatment effect of vacuum preloading method decreases greatly with the increase of depth.The increase in the shear strength of the deep cross plate in the test area is about 10% lower than that in the shallower layer,while the corresponding depth attenuation in the comparison area is about 30%.(3)The combined application of electro-osmotic method can effectively shorten the consolidation time of vacuum preloading method to treat soft soil foundation.When the consolidation degree of 80% is required,the construction period of the test area is about 36% shorter than that of the comparison area,and the energy consumption is about 18% lower.Especially when a high degree of consolidation is required,electroosmotic combined with vacuum preloading method has obvious advantages in construction period.(4)When the electro-osmosis method is combined with the vacuum preloading,if the electro-osmosis range is in the shallower soil layer above 6m depth,the effect may not be obvious.The advantage of the electro-osmotic combined with vacuum preloading method lies in the treatment of deep soft soil.(5)The combination of electro-osmosis should be used in the middle or late stage of vacuum preloading,and the voltage should be appropriately reduced in the early stages of electro-osmosis,and then increased in the middle and late stages of electroosmosis,which can greatly reduce energy consumption while ensuring the treatment effect.In addition,this paper summarizes the construction of electro-osmosis combined vacuum preloading method,points out the problems in construction,and gives relevant suggestions,providing reference for the engineering application of electro-osmosis combined vacuum preloading method.