Method D: Extensive numerical methods which involves all rock mass mechanisms. Method C: Basic numerical modelling which captures most relevant rock mass mechanisms, and Kirsch equations for stress analysis around circle excavations, Method B: Engineering design based on simplified analytic solutions e.g. Method A: Engineering design based on the previous empirical design and experiences, įigure 1: Eight different approaches to rock engineering design and rock mechanics modelling Īs illustrated in Figure 1 the four columns represent the four main modelling methods: Hudson in 2001 developed eight approaches based on four methods and two levels, (Figure 1). These modelling approaches can be presented in different ways. There is a wide spectrum of modelling approaches as rock engineering models are designed for different purposes. As discussed before, the rock mass property is exclusively depended on the location and the site under study, so a computer model based on the specific site characteristics of the rock mass should be adopted in order to have a model with most similar behavior to the reality. The ability of the rock mechanics model of predicting the behavior of the rock mass is achieved through the variety of modelling methods. These projects can be for civil engineering purposes or for mining, petroleum or environmental engineering.
Rock engineering projects can be categorized into surface or underground rock engineering. This can be achieved only on the basis of scientific knowledge and also empirical judgments supported by accumulated experiences through long-term practices. In most cases the model does not need to be complete but to be adequate for the purpose of the study. This is the reason that the rock mechanics modelling for rock engineering projects are both science and art.
However, the quality and quantity of the supporting data for rock engineering projects can never be complete due to the inherent variability of the rock mass property. Therefore, designing a rock engineering model requires comprehensive knowledge of the geomaterial, engineering properties, and parameters of the rock mass. Rock mechanics projects are getting more complex, larger, and also more demanding for modelling requirements.
The rock mass is a fractured porous material which contains fluids like water, oil, and gas which they can significantly affect the in situ stress fields under different temperature and pressure conditions. Due to dynamic movements of the upper crust of the earth, the rock mass is under continuous dynamic stresses this happens through diversity of earth related movements like tectonic movements, earthquakes, glaciation cycles, subsidence, etc. Rock mass is a massively Discontinuous, Inhomogeneous, Anisotropic and Non-Elastic (DIANE) material. Rock mass is a natural geological material, therefore the physical and engineering properties of it have to be established rather than defined through a manufacturing process like steel. 3 Advantages and disadvantages of different numerical methods for rock mechanics.2.4 Comparison of FDM and FEM for rock mechanics applications.2.1 Characterization of rock masses for numerical methods.