| Tideland slurry dredged from the nearby seabed has been used as the main fill material for land reclamation.However,it is typically characterized by high water content,high compressibility,low undrained shear strength,low coefficient of consolidation,low penetrability.Foundation improvement must be implemented before construction because of its bad engineering properties.Usual foundation treating methods could not achieve a satisfactory because they relied on hydraulic permeability of soil.The electrical permeability coefficient of the soil is independent of the hydraulic permeability,so electrokinetic dewatering is an effective technique used to improve fine-grained soft soils during land reclamation projects.However,the application of this method was limited by consolidation mechanism,energy demand and the soil difference of settlement.Series of electroosmotic laboratory tests were conducted in a self-made tank to investigate the impact of combination between current intermittence and the movable electrodes on electroosmotic effect.First of all,in order to study the effect of thermal effect on electroosmotic drainage under different potential gradients,an evaporative condensation device has been developed to collect the evaporation water produced by thermal effect,the consolidation properties and the effect of electroosmotic to physical and mechanical properties of soil were given after analyzing parameters mentioned above.The results showed that the temperature increases first and then decreases,and the evaporated water and electrolytic water increased with increasing voltage gradient.The total water loss increases with the increase of potential gradient,and the higher the potential gradient is,and the lower the soil moisture content is,the higher the shear strength is.When the potential gradient is 1.25V/cm,the less the proportion of electroosmotic drainage to total water loss,and the electroosmosis efficiency is low.Therefore,A voltage gradient greater than 1.0 V/cm had no significant effect on the drainage.The intermittent current combined with anode moving method is proposed to deal with the defects such as the soil difference of settlement in the process of tideland sludge consolidated by electroosmotic method.The tests were divided into two stages.in the first stage,the effect of the different power-off ratio is studied based on the fixed power-on time.And then,the optimized power-off ratio is obtained by comparison with the continuous conduction.In the second stage,at the optimized power-off ratio,the electrode spacing ishalved to study the soil consolidation effect near the cathode.Conclusions can be drawn as follows: The intermittent current combined with electrode moving can reduce the soil difference of settlement and shear strength between the cathode and anode after electro-osmotic consolidation.The optimization methods were adopted to reduce energy consumption and increase the drainage rate.laboratory experiments are performed to investigate the effects of anodic moving on the electroosmotic consolidation of four samples using electro-osmosis.The variation laws of their parameters were summarized,thus,the test results demonstrated that the anodic moving had important influence on the change of the electric permeability coefficient and the energy consumption coefficient under different consolidation degrees.The technique of anodic moving was used to improve electroosmotic efficiency at later stage and the increase of water drainage;When the consolidation degree reaches 60%,anode moving can make the water content of soil mass relatively more homogenous. |
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