Abstract
Rock tensile strength (TS) is an essential parameter for designing structures in rock-based projects such as tunnels, dams, and foundations. During the preliminary phase of geotechnical projects, rock TS can be determined through laboratory works, i.e., Brazilian tensile strength (BTS) test. However, this approach is often restricted by laborious and costly procedures. Hence, this study attempts to estimate the BTS values of rock by employing three non-destructive rock index tests. BTS predictive models were developed using 127 granitic rock samples. Since the simple regression analysis did not yield a meaningful result, the development of models that integrate multiple input parameters were considered to improve the prediction accuracy. The effects of non-destructive rock index tests were examined through the use of multiple linear regression (MLR) and adaptive neuro-fuzzy inference system (ANFIS) approaches. Different strategies and scenarios were implemented during modelling of MLR and ANFIS approaches, where the focus was to consider the most important parameters of these techniques. As a result, and according to background and behaviour of the ANFIS (or neuro-fuzzy) model, the predicted values obtained by this intelligent methodology are closer to the actual BTS compared to MLR which works based on linear statistical rules. For instance, in terms of system error and a-20 index, values of (0.84 and 1.20) and (0.96 and 0.80) were obtained for evaluation parts of ANFIS and MLR techniques, which revealed that the ANFIS model outperforms the MLR in forecasting BTS values. In addition, the same results were obtained through ranking systems by the authors. The neuro-fuzzy developed in this study is a strong technique in terms of prediction capacity and it can be used in the other rock-based projects for solving relevant problems.
Highlights
This article is an open access articleIn rock engineering, rock fracture mechanics are associated with the behaviours of rock deformation and failure patterns caused by crack initiation and propagation
This study focuses on the use of only non-destructive tests, i.e., ultrasonic velocity, Schmidt’s hammer rebound, and density in assessment and evaluation of tensile response of the rock samples
A comprehensive series of laboratory tests were performed on more than 154 block samples brought from a water transfer tunnel project
Summary
This article is an open access article. Rock fracture mechanics are associated with the behaviours of rock deformation and failure patterns caused by crack initiation and propagation. The growth of cracks in rocks happens due to small micro-cracks, micro-defects, and failures of large preexisting fractures in rock [1]. Rock has lower tensile resistance compared to compressive and shear resistance due to its brittleness properties. Sustainability 2021, 13, 10541 behaviour such as tensile properties is essential for solving geotechnical problems during underground openings, surface excavation, and rock blasting and to ensure underground cavern stability. There are many methods for predicting rock tensile strength (TS). Direct test is considered the most effective method to derive the tensile capacity of rock specimen
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