There are a lot of soft clay widely distributed in southeast coastal areas of our country.The soft clay has the characteristics of high moisture content,low permeability,more fine particles and low shear strength,it needs to be effectively strengthened before it can be used in engineering.At present,the commonly used soft foundation treatment methods,such as vacuum preloading method and pile preloading method,are limited by the soil hydraulic permeability coefficient,the reinforcement efficiency and deep soil reinforcement effect need to be improved Electro-chemical method is based on the electroosmosis method to internal chemical grouting to enhance soil electroosmosis reinforcement effect of a kind of method,because of its effect on soil reinforcement effect to promote significant and become the main research direction of electroosmosis method However,the microscopic strengthening mechanism of the electro-chemical method is not clear at present,which leads to the problems of high energy consumption and uneven strengthening effect that cannot be fundamentally solved,restricting the application of the electro-chemical method in engineering practice.Based on this,this paper uses a self-made model box to conduct indoor electrochemical reinforcement test research,and analyzes the macro reinforcement effect and the change of soil micro characteristics according to the grouting ion characteristics.The main conclusions are as follows:(1)The influence of grouting method on electrochemical reinforcement effect was studied.The results show that the main ions acting on the drainage are low-valent cations such as Na+and K+,and the overall transport amount of high-valence cations is small.The injected high-valent cations mainly improve the drainage effect by replacing the low-valence cations on the surface of the unearthed particles and promote the chemical cementation reaction in the cathode area to improve the reinforcement effect.The more high-valence ions are injected,the more low-valence ions are transported.Combined reagent grouting can effectively reduce the loss of calcium ions and promote the strength growth of cathode soil.In the case of the same total amount of injected cations,the anode strength is higher when Ca Cl2 is injected alone,but the reinforcement effect is more uniform when the combination of Ca Cl2 and Na2Si O3 solution is injected.(2)Based on the above research results,ion migration in the electroosmotic process leads to significant differences in ion content in different areas of soil before and after treatment,which is easy to affect the soil structure.Therefore,the influence of cation valaence on reinforcement effect and microscopic pore characteristics is studied.The results show that the increase of the price of injected cations has obvious influence on the electro-chemical reinforcement effect and the microscopic characteristics of soil.Increasing the valence of injected cations can effectively improve the electricalpermeability coefficient and conductivity of soil,and significantly improve the shear strength of treated soil.After electro-chemical treatment,the overall pore volume of soil increased due to the flocculation caused by cationic injection.However,pore redistribution of soil resulted in a more uniform distribution of the overall pore size of soil,especially in the cathode region.The cementation material and precipitation generated by chemical cementation reaction caused by high-valence ions reduced the influence of flocculation.The pore volume and pore size distribution of treated soil are better than those of low-valence ions.(3)The influence of cationic radius in grouting reagent on the effect of electro-chemical method for strengthening soft soil foundation is studied.The results show that the increasing of the ionic radius of the cations injected into the agent can significantly improve the current,drainage volume,drainage rate,and electrical permeability coefficient during electro-osmosis,and shear strength after treatment.Among them,calcium ion has the best reinforcement effect.The microscopic image of the soil after the tests also show that the soil after calcium ion treatment has a higher degree of compactness. |