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摘要
The essential cause of the deformation of saline soil in seasonal frozen region is the excess water and salt. Electroosmotic treatment can accelerate the dewatering of soil by driving the salt ions, the excessive water content of anodic soil is also induced subsequently, which will cause seriously freezing deformation. In this work, a set of comparison laboratory tests were performed in customized apparatus to investigate the influence of electroosmosis and calcium sodium application (0, 5%, 10%, 15%) on the deformation of sodium sulfate saline soil. The testing results indicate that electroosmosis incorporated with calcium chloride can dramatically improve the soil’s conductivity and drainage rate. Compared with sole electroosmotic treatment, the accumulative drainage of soil treated with electroosmosis-calcium chloride increases by more than 35%. Moreover, the surplus Na+ and SO42- ions migrate to cathode and anode respectively, and exit with water flow, resulting in the significant decrease of frost heave and salt expansion. The free Ca2+ ions involved in anodic electrolyte migrate to cathode under the external electric field and react with OH? ions. The obtained Ca(OH)2 serves as cementing agents and improves the integrity of soil matrix. Also, the residual Ca2+ ions deported to cathodic area react with some soluble silicate, forming the calcium silicate hydrate (C-S-H) which coate on soil particle surface and increases the internal friction angel of soil. After electroosmosis-calcium chloride treatment, the microstructure and resistance to deformation of sodium sulfate saline soil were obviously improved. And the mass concentration of 10% calcium chloride solution achieves the best reinforcement. By comparison with sole electroosmosis treatment, the drainage volume increases by 70%, and the shear strength of cathodic soil increases 27. 1 kPa, the freezing deformation decreases by 65. 1%. While, once the mass concentration of calcium chloride exceeds 10%, the soil shear strength and drainage decrease because of the blockage of electroosmotic channel and corrosion of electrodes, resulting in the increment of soil deformation. ? 2023 South China University of Technology.
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