Abstract

The prediction of the support pressure (Pi) and the development of the ground reaction curve (GRC) are crucial elements of the convergence–confinement procedure used to design underground structures. In this paper, two different types of artificial neural networks (ANNs) are used to predict the Pi of circular tunnels in elasto-plastic, strain-softening rock mass. The developed ANNs consider the stress state, the radial displacement of tunnel and the material softening behavior. Among these parameters, strain softening is the parameter of the deterioration of the material’s strength in the plastic zone. The analysis also presents separate solutions for the Mohr–Coulomb and Hoek–Brown strength criteria. In this regard, multi-layer perceptron (MLP) and radial basis function (RBF) ANNs were successfully applied. MLP with the architectures of 15-5-10-1 for the Mohr–Coulomb criteria and 17-5-15-1 for the Hoek–Brown criteria appeared optimum for the prediction of the Pi. On the other hand, the RBF networks with the architectures of 15-5-1 for the Mohr–Coulomb criterion and 17-3-12-1 for the Hoek–Brown criterion were found to be the optimum for the prediction of the Pi.

Highlights

  • It was conducted on the basis of the commonly known coefficient of determination (R2 ), root-mean-square error (RMSE), and mean absolute error (MAE) [22,24,27,28,40,41,42,43,44,45,46,47]

  • The available classical methods require a broad understanding of the governing mechanisms of the convergence–confinement method and programming skills to derive the ground reaction curve (GRC) for the elasto-plastic, strain-softening rock mass

  • Pi of circular tunnels [4], the applicability of another intelligent method is investigated in this study to obtain even more accurate predictions

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Summary

Introduction

Convergence–confinement is a broadly applied method to design underground structures. In this method, a ground reaction curve (GRC) is applied to evaluate the interaction between the rock mass and the support system near the tunnel’s face at the time of construction [1,2,3]. The classical problem of a circular tunnel constructed in the rock mass medium is illustrated in Figure 1b (according to [4]). This problem uses two well-known rock mass strength criteria: Mohr–Coulomb and. These criteria are usually adopted to investigate the behavior of materials.

Description of: of:
Methodology
Performance Evaluation
The Mohr–Coulomb Criterion
Comparison with Previously
Findings
Conclusions and Perspectives
Full Text
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