Electro-osmosis Combined With Vacuum Preloading Field Test Study And Numerical Analysis

China’s coastal areas have been widely distributed with soft soils.In order to construct home for human beings,we must first do gound treatment.In this paper,reinforcement effect of electro-osmosis combined with vacuum preloading by tubular EKG and slablike EKG materials and its consolidation theory were studied through field test,theoretical derivation and numerical calculation,rendering a reference for relevant engineering practice.The following conclusions are drawn through the research.(1)The strength index(vane shear strength,static cone penetration test)of soils treated by electro-osmosis combined with vacuum preloading for 54 days could reach the strength of vacuum preloading for 135 days.Also,the strength of the soil treated by electro-osmosis combined with vacuum preloading was more uniform along the depth direction.The surface sedimentation was larger,the pore pressure dissipating faster and the water content of deep soil being lower,which indicated that the electro-osmosis combined with the vacuum preloading method could achieve higher soil treatment requirements in a shorter period.Therefore,it has broader application prospect.(2)The tubular EKG and plate EKG materials were used in the field experiment.The results show that the strength of soil treated by tubular EKG was higher,the settlement being larger,the pore pressure dissipation being quicker,the drainage effect being better.The main reason is the fact that the drainage channel in tubular EKG is hard to be clogged.(3)Based on the consolidation theory and practical engineering,boundary conditions were set with vacuuming in both cathnode and anode as well as vacuum attenuation.The mechanism of electro-osmosis combined with vacuum preloading was explained from the perspective of ultra-static pore pressure.(4)The vertical layered power technology was put forward and investigated in a field electro-osmosis test,which aimed to increase the reinforcement effect of the deep soil.Test results shows that this method can reduce the water content of the deep soil and improve its strength.However,the treatment effect of the upper layer was unsatisfactory because of the shorter reinforcement time when compared with the traditional power supply method.Numerical analysis results show that vertical layered power technology may cause surface settlement to be decreased.(5)The settlement of electro-osmosis combined with vacuum preloading can be effectively predicted by sovling Biot consolidation equation,pore water migration equation and charge transport equation simultaneously.Although slightly deviation existing,the numerical results show the same trend with measured data.Therefore,the numerical method can be used to calculate the settlement in order to design the construction parameters and control the construction process before the engineering practice.(6)The intensity and energy of electric field in electro-osmosis was analyzed by analyzing the electric field characteristics with FEM and quantitative description of the electric field was presented by drawing Sα-α curve and ηα-α curves.The influence of the size difference between the tube EKG electrode and plate EKG electrode and the vertical layered power technology on the electric field distribution were analyzed respectively,rendering a reference for engineering design.