Research Article: An analytical solution for two-dimensional vacuum preloading combined with electro-osmosis consolidation using EKG electrodes

Date Published: August 3, 2017

Publisher: Public Library of Science

Author(s): Yang Shen, Chenchen Qiu, Yande Li, Wen Shi, Xiaoxi Rui, Varenyam Achal.

http://doi.org/10.1371/journal.pone.0180974

Abstract

China is a country with vast territory, but economic development and population growth have reduced the usable land resources in recent years. Therefore, reclamation by pumping and filling is carried out in eastern coastal regions of China in order to meet the needs of urbanization. However, large areas of reclaimed land need rapid drainage consolidation treatment. Based on past researches on how to improve the treatment efficiency of soft clay using vacuum preloading combined with electro-osmosis, a two-dimensional drainage plane model was proposed according to the Terzaghi and Esrig consolidation theory. However, the analytical solution using two-dimensional plane model was never involved. Current analytical solutions can’t have a thorough theoretical analysis of practical engineering and give relevant guidance. Considering the smearing effect and the rectangle arrangement pattern, an analytical solution is derived to describe the behavior of pore-water and the consolidation process by using EKG (electro-kinetic geo synthetics) materials. The functions of EKG materials include drainage, electric conduction and corrosion resistance. Comparison with test results is carried out to verify the analytical solution. It is found that the measured value is larger than the applied vacuum degree because of the stacking effect of the vacuum preloading and electro-osmosis. The trends of the mean measured value and the mean analytical value processes are comparable. Therefore, the consolidation model can accurately assess the change in pore-water pressure and the consolidation process during vacuum preloading combined with electro-osmosis.

Partial Text

China has a vast territory, but the distribution of land is uneven. A large amount of population has gathered in eastern coastal regions, which significantly reduces the available land for economic development. Reclaiming land along the sea and beach is usually carried out in this area to solve this problem. The soft clay and dredged silt after reclamation are characterized by high water content and high compressibility but low shear strength. There are several ways for land reclamation, for example, the electro-osmotic dewatering method could drain water out of the low permeable soft clay quickly. However, due to the electro-chemical reaction, metal electrode would be corroded and of which has restricted its application [1]. The vacuum preloading could be used for foundation treatment with a large area of soft clay; a long period of construction was usually required. Hence, a second treatment needs to be carried out [2]. Thus, conventional preloading, vacuum preloading and electro-osmosis require a long period of construction and have low efficiency.

By integrating the Eq (13) over the z variable,: the following equation can be obtained:
∂us∂z=−2γwqw,psz[∂ε∂t(bc−bw)+keU02bc]+C1(14)

The analytical solution using two-dimensional plane model and EKG electrodes were never reached before. Current analytical solutions can’t give relevant guidance for practical engineering. Given the past theoretical derivation, a two-dimensional plane drainage model was proposed for vacuum preloading combined with electro-osmosis consolidation. New EKG electrodes were used in this model. The analytical solution was derived to describe the behavior of the pore water pressure and consolidation in the anode considering the smearing effect. Therefore, the analytical derivation with different two-dimensional models for vacuum preloading combined with electro-osmosis was further developed. Additionally, practical engineering of vacuum preloading combined with electro-osmosis using EKG electrodes can provide a comprehensive reference and guidance.

The following symbols are used in this article:

 

Source:

http://doi.org/10.1371/journal.pone.0180974

 

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