A One-Dimensional Model Test On The Treatment Of Dredged Sludge By Electrosilicification

Every year,rivers and lakes will produce a large amount of dredged sludge,forming a large area of dredged sludge foundation.This kind of sludge has the disadvantages of high fine content,high water content,high compressibility,low shear strength and low permeability.Therefore,finding an efficient method to strengthen the dredged sludge foundation is the key to improve the utilization rate of land resources.The most common methods to deal with dredged sludge foundation are solidification and vacuum preloading.The engineering cost of curing method is higher.Due to the small hydraulic permeability coefficient of fine grained soil,the vacuum preloading method is affected by the hydraulic permeability coefficient,and the dredged sludge with high fine grained content has poor treatment effect.It is easy to produce silting in the later stage,and the reinforcement effect of deep sludge is not good,only the hard crust layer is formed on the surface of sludge.Therefore,electroosmotic method is considered to be more suitable for dredging sludge foundation.Because the electrical permeability coefficient is not affected by the grain size of soil,the effect of the dredged sludge treatment with high content of fine soil is obviously better than that of vacuum preloading method.And there is no blockage problem encountered by vacuum preloading method.However,problems such as high energy consumption,serious corrosion and obvious cracks hinder the popularization of electroosmosis.Scholars at home and abroad put forward the electrochemical method of adding additives in the electroosmosis to improve the shortcomings of the electroosmosis method and improve the effect of drainage consolidation.However,most of the additives can not be cemented and hardened,or even cause secondary pollution to the foundation,and are expensive.It is not conducive to the large area use of actual engineering.Due to the excellent effect of cementing hardened soil,and the obvious advantages of the added agents,such as non-toxicity,non-pollution and low cost,electric silicification method has shown a broad engineering prospect in the electrochemical method.Based on this,the consolidation test of indoor electroosmotic grouting was carried out by the self-made one-dimensional plexiglass model box using the electric silicification method.Firstly,carry out influence test of different anodic grouting pipe positions on the drainage consolidation of electric silicification method.Secondly,it discusses the influence of different interval grouting time on the reinforcement of fill by electric silicification method to strengthen the dredger fill.Finally,considering the grouting position and interval grouting time at the same time,four sets of electro-mechanical silicidation tests with different grouting way are set up.From the test results,it can be concluded that the optimal anode tube follow-up grouting position is 110mm away from the anode for injecting calcium chloride solution and the cathode for injecting water glass solution（Na₂Si O₃）.And the best time for interval grouting is the injection of water glass（Na₂Si O₃）solution at the 0th hour and the injection of calcium chloride（Ca Cl₂）solution at the 12th hour.In addition,the best grouting way in the test is the average intermittent injection of calcium chloride solution（Ca Cl₂）in the anode area and sodium silicate solution（Na₂Si O₃）in the cathode.The parameters such as the position of anode grouting pipe,interval grouting time and grouting method obtained from the test can effectively help the implementation and application of the electric silicification technology in the field construction.