| Soft soil is widely distributed in China.With the development of urban construction,soft foundation treatment has become the key in engineering construction.Electric chemical reinforcement method can improve the strength of soft foundation by drainage consolidation and ion migration.Compared with other traditional soft foundation treatment methods,it has the advantages of short treatment period,remarkable strength improvement and good uniformity.However,the research on the mechanism of electrochemistry reinforcement is not perfect,and the engineering application is rarely reported.In this paper,the feasibility and applicability of this method in engineering application are determined by laboratory test,field test,microscopic mechanism analysis and engineering practice.The main research work and achievements are as follows:1.According to the formation process and chemical characteristics of clay mineral crystals,the soil-water interaction mechanism of clay particles,the theory of diffusion double layer and the mechanism of ion migration in soil under the action of electric field are expounded.2.Clay particles are negatively charged,they can adsorb polar molecular water and hydrated cations in the soil to form a double electric layer structure,the free water,partially bound water and hydrated cations in the soil move in a directional manner under the electric field,descresing the thickness of the double layer.3.There are significant changes in the p H between the anode and cathode under the electric field,which form a strong alkalinity near the cathode.on the one hand,the metal cations precipitate near the cathode,blocking the drainage channel,on the other hand,the drainage can be promoted by injecting chemical solution.a large amount of cementitious material can be formed to change the microstructure of soil.4.The coefficient of power permeability varies over time was fitted by the test data in electrokinetic stabilisation.5.The mechanism of increasing soil strength near anode and cathode is studied,in which the soil strength is improved due to drainage consolidation near anode,and the soil strength is greatly improved with age due to the formation of a large amount of cementitious material in cathode.6.The soil structure,mineral composition and chemical composition of soil before and after reinforcement were analyzed by means of polycrystalline X ray powder diffractometer(XRD),scanning electron microscope(SEM),energy dispersive ray fluorescence spectrometer(XRF)and Fourier transform infrared spectrometer(FTIR),which proved that the microstructure and mineral composition of soft soil changed significantly by electrochemically strengthened soil.7.The field test in Zhuhai area shows that the moisture content of soil is reduced by 18.4～29%,the shear strength of cross plate is increased by 1.6～2.3 times,and the cohesion is increased by 1.4～2.2 times. |
