Nearest Linear Failure Surface, a New Method to Determine the Reliability of Numerical Models in Geomechanics

Document Type : Research Article

Author

Department of mining and Metallurgical Engineering/ Yazd University

10.22034/anm.2024.18529.1643

Abstract

In geomechanical systems, reliability analysis aims to determine the failure probability according to the uncertainties existing in rock mass properties and support materials as well as diagnosing the significance of each uncertainty. Although there are very diverse methods to determine the reliability of a geomechanical models, employment of precise methods for determining the reliability of a numerical model is practically impossible due to computational difficulties. The only general solution to solve the reliability problem is to use Monte Carlo simulation. However, for most systems, with engineering accuracy, a thousand numbers of realizations are required in order to use Monte Carlo stimulation. Although this number of realizations for analytical functions can be performed very quickly, running this number of realizations for a numerical code is practically impossible. In proposed Nearest Linear Failure Surface method (NLFS), with the least number of runs, the reliability of rock space and its failure probability are investigated during a short period of time and appropriate accuracy. The idea of NLFS method is inspired by finding the design point (β-point in well-known First Order Reliability Method) assuming that the performance function is linear. In this research, a computerized code has been prepared to run NLFS method and by combining this code with FLAC 2D software, reliability of an underground road tunnel with uncertain cohesion, friction angle, and tensile strength surrounding rock was determined. The results indicate the high efficiency of proposed method in determining the reliability of numerical models in a very short time and with high accuracy.

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