Large-Scale Model Swelling Potential of Expansive Soils in Comparison with Oedometer Swelling Methods
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RESEARCH PAPER
Large‑Scale Model Swelling Potential of Expansive Soils in Comparison with Oedometer Swelling Methods Yousif Ismael Mawlood1 · Rizgar Ali Hummadi1 Received: 19 February 2018 / Accepted: 24 August 2019 © Shiraz University 2019
Abstract Samples of natural high, medium and low expansive soils (respectively, designated as Soil-A, Soil-B and Soil-C) were collected from different locations to obtain a wide range of swelling criteria. Soil-B was mixed with 5%, 10%, 15%, 20% and 25% bentonite mineral. The swell potentials of the expansive soil samples were measured using standard test methods for natural deposits and reconstituted samples. The non-homogeneous soil formation in the field and the existing micro- and macrocracks due to drying shrinkage hindered the accurate prediction of the swelling index of the small-scale samples under different stages of field conditions. A large-scale model was established to improve the accuracy and reliability of the test results. The proposed model was designed to estimate the swelling potential of the reconstituted samples under simulated field conditions. The empirical relationships of the multiple regression analysis models were determined on the basis of the best statistical information criteria using STATGRAPHICS Centurion XVII V.17.200. Results supported the prediction of the swelling potential on the basis of the physical properties of soils, thereby alleviating the need to conduct oedometer tests. The proposed relationships and the equations in the literature were compared with the test results of these samples. Overall, the oedometer technique overestimates ground heave by approximately 1.5%, and the proposed relationships are consistent with the measurement results of some researchers but inconsistent with those of others. Keywords Expansive soil · Swell potential · Field density · Reconstituted sample · Large-scale model · Multiple regression List of symbols Soil-A High expansive soils Soil-B Medium expansive soils Soil-C Low expansive soils FS Vertical free swell LL Liquid limit PL Plastic limit PI Plasticity index ID One-dimensional CBR California bearing ratio μ Micrometre 𝛾t Total unit weight Electronic supplementary material The online version of this article (https://doi.org/10.1007/s40996-019-00307-6) contains supplementary material, which is available to authorized users. * Yousif Ismael Mawlood [email protected]; [email protected] 1
Rizgar Ali Hummadi [email protected]; [email protected]
Department of Civil Engineering, College of Engineering, Salahaddin University-Erbil, Erbil, Iraq
𝛾d Dry unit weight e Void ratio Si Initial degree of saturation wi Initial water content C Percentage of clay finer than 5 μm CA Percentage of clay finer than 2 μm CC Percentage of clay finer than 1 μm A Clay’s activity CEC Cation exchange capacity 𝜌d The initial dry density of soil 𝜌w The density of water MDD Maximum dry density OMC Optimum moisture content FS Measured oedometer free swelling FSA(LS) Measured
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