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Geomechanics and Engineering
  Volume 28, Number 4, February25 2022 , pages 385-396
DOI: https://doi.org/10.12989/gae.2022.28.4.385
 


A computational estimation model for the subgrade reaction modulus of soil improved with DCM columns
Ali Dehghanbanadaki, Ahmad Safuan A. Rashid, Kamarudin Ahmad, Nor Zurairahetty Mohd Yunus and Khairun Nissa Mat Said

 
Abstract
    The accurate determination of the subgrade reaction modulus (Ks) of soil is an important factor for geotechnical engineers. This study estimated the Ks of soft soil improved with floating deep cement mixing (DCM) columns. A novel prediction model was developed that emphasizes the accuracy of identifying the most significant parameters of Ks. Several multi-layer perceptron (MLP) models that were trained using the Levenberg Marquardt (LM) backpropagation method were developed to estimate Ks. The models were trained using a reliable database containing the results of 36 physical modelling tests. The input parameters were the undrained shear strength of the DCM columns, undrained shear strength of soft soil, area improvement ratio and length-to-diameter ratio of the DCM columns. Grey wolf optimization (GWO) was coupled with the MLPs to improve the performance indices of the MLPs. Sensitivity tests were carried out to determine the importance of the input parameters for prediction of Ks. The results showed that both the MLP-LM and MLP-GWO methods showed high ability to predict Ks. However, it was shown that MLP-GWO (R = 0.9917, MSE = 0.28 (MN/m2/m)) performed better than MLP-LM (R =0.9126, MSE =6.1916 (MN/m2/m)). This proves the greater reliability of the proposed hybrid model of MLP-GWO in approximating the subgrade reaction modulus of soft soil improved with floating DCM columns. The results revealed that the undrained shear strength of the soil was the most effective factor for estimation of Ks.
 
Key Words
    DCM columns; grey wolf optimization; soft soil; subgrade reaction modulus
 
Address
Ali Dehghanbanadaki: Department of Civil Engineering, Damavand Branch, Islamic Azad University, Damavand, Iran
hmad Safuan A. Rashid, Kamarudin Ahmad,
Nor Zurairahetty Mohd Yunus and Khairun Nissa Mat Said: 2Department of Geotechnics & Transportation, School of Civil Engineering, Faculty of Engineering,
Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia
 

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