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| Macro and micro analyses of stepped vacuum preloading combined with intermittent electroosmosis for treating dredger slurry#br# |
| LIU Feiyu1，ZHANG Zhipeng1，WANG Jun2，YUAN Guohui2，FU Hongtao2#br# |
(1. Department of Civil Engineering，Shanghai University，Shanghai 200444，China；2. School of Civil Engineering and Architecture，Wenzhou University，Wenzhou，Zhejiang 325035，China)
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Abstract In order to solve the problems of blockage of drainage plate and large energy consumption in vacuum preloading combined with electroosmosis(VPEO)，a combination method of stepped vacuum preloading and intermittent electroosmosis(SVPIEO) was proposed. Four sets of indoor model tests were carried out，and the water discharge and the surface settlement of soil were monitored. The reinforcement effect was evaluated，and the improvement effect of SVPIEO on VPEO in soil reinforcement and silting was investigated. In addition，the soil microstructure images were obtained by means of scanning electron microscopy，and the changes of soil pore characteristics after VPEO and SVPIEO were analyzed by image processing software. The experimental results show that，for SVPIEO，applying stepped vacuum pressure can alleviate the drainage board blockage，and intermittent energization can reduce anodic corrosion and increase soil current to promote soil drainage. Compared with VPEO，the water discharge and the vane shear strength of soil by SVPIEO increase by 13.2% and 19.2% respectively，and the soil moisture content decreases by 13.7%，showing significant improvement effect. After treatment by SVPIEO，the apparent porosity，number of pores and average pore area of the soil are larger. The smooth drainage channel of the soil helps drainage，and the soil pores are arranged more orderly and the pore shape is more complicated.
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2020, Vol. 39 
