Study on pore size effect of low permeability clay seepage
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ORIGINAL PAPER
Study on pore size effect of low permeability clay seepage Jian Chen 1,2 & Yingguang Fang 1,2 & Renguo Gu 1,2 & Haokai Shu 1 & Lingzhen Ba 1,2 & Wei Li 1 Received: 15 June 2018 / Accepted: 22 February 2019 # Saudi Society for Geosciences 2019
Abstract Low-permeability clays are characterized by a large amount of clay minerals and a special distribution of pore sizes, so their seepage behavior shows an obvious pore size effect. Therefore, conventional seepage theories show deviations in describing the seepage behavior of low-permeability clays. This paper analyzes two reasons for the pore size effect in low-permeability clay seepage: the pore distribution property and the electric double layer effect of the clay surface. Considering these two factors, the seepage theory of the pore size effect based on the microscale seepage of the circular tube model is proposed. The rationality of this theory is tested by the seepage experiments of natural undisturbed clay and artificial clay, and from these experiments, three beneficial conclusions are drawn: (1) The results of the pore size effect seepage theory are in good agreement with the experimental results and are better than the modified Kozeny-Carman equation; (2) The properties of the electric double layer have a certain regular influence on the seepage behavior of the clay; (3) Considering the properties of the soil pore size distribution, the results obtained by using the pore size effect theory are much closer to the experimental results than the results calculated using the average pore diameter of the clay. Keywords PermeabilityPore size effect . Electric double layer . Pore size distribution . Kozeny-Carman equation
Introduction The seepage property of soil directly affects the seepage process and distribution of the seepage field. The seepage field and stress field coupled together will change the deformation and strength properties of the soil, which then cause a deformation of the geosphere, and variations in slope stability and other engineering safety issues. (Gan et al. 2018; Conte and Troncone 2011; Nguyen et al. 2017; Zanj and Veiskarami 2015). Therefore, pioneers in civil engineering proposed theories for sandy soil, namely, Darcy proposed Darcy’s law (Gisonni 2003) for sandy soil and Kozeny and Carman proposed an equation referred to as the Kozeny-Carman (K-C) equation (Carman 1956) for the seepage of uniform sand and gravel soil. These theories are beneficial for subsequent Editorial Handling: L. Xiao * Jian Chen [email protected] 1
School of Civil and Transportation Engineering, South China University of Technology, Guangzhou, China
2
State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou, China
engineering research. However, with a large number of engineering cases and laboratory test, some scholars have found that the results of some fine-grained soil seepage tests have deviated from the Darcy’s law (Mitchell and Younger 1967), especially low-velocity seepage for low- permeability s
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