Laboratory Model Test On Electrochemical Stabilization In Soft Soil

Compared with other traditional ground treatment methods, electrochemical stabilization in soft soil has the advantages of noiselessness and non-dusting, construction convenience and environment-friendly. With the development of power infrastructure, electrical energy will be more affordable and study of this new ground treatment has great significance.Supported by National Natural Science Foundation Project, Study on electrochemical stabilization of soft soil and its nature of iron cementation, theoretical analysis and experiments were combined. Several experiments were carried out and the factors that have influenced on electrochemical stabilization were analyzed. It will settle foundation for experience for spot and project application.In this paper, the main work and results are shown as follows:According the principle of electrochemical stabilization, laboratory model test equipments which could provide stable direct current, simulated groundwater and overlying load, achieve electrochemical stabilization were designed. Results show that current was reduced, voltage and resistance were increased. This is because of the chemical cement around electrode which plays a role of interlayer insulation. For resistance is anisotropic, when the current is reversed, it will mutant. The change of electrical parameters is closely related to electrochemical reaction. When current reduced to zero and resistance stabilized, electrochemical stabilization is completed.Compared the salinity and conductivity of different positions of soil surface, the result show that salinity and conductivity of cemented soil are 20-25% less than non-cemented soil. This suggests that the ion in soil drived by current will take part in the reaction with mental ion electrolyzed by electrode, the more cementing soil, the more ion of soil take the reaction. Therefore salinity reduced and resistance increased.The researches on the structural characteristics, strengthen distribution law and load capacity property was made. The results were as follows:firstly, ferruginous cemented piles are mainly composited of two layers:one is the coral layer which has dense structure and hard texture, the other is the affected layer which has rigid texture and is fragile. The ranges of these two layers are respectively 8 times and 12 times thickness of electrode diameter. Secondly, the strength of cemented soil is inversely proportional to the diameter distance of electrode and there is strong discontinuous surface between these two layers. Bearing capacity from the original 6-10kPa raised to the 30-60kPa after reinforce.These factors, such as groundwater, current reversed time, electrode shape and NaCl reagent) which have influence on electrochemical stabilization are studied. Groundwater and longer current reversed time make the differences between range of movement of ions under and upper groundwater become larger. NaCl will increase the corrosion of the electrode and make the strength of cement pile reduce. Solid cylindrical electrode pile has better effect on electrochemical stabilization than porous tubular electrodes.After microscopic experiments and chemical analysis, it is found that structure of cemented soil is more compact and the content of iron of cemented soil is more than non-reinforced soil These are the reasons why strength of cementitious pile increases.