The benefits of Material Volume Meshes in 3D Slope Stability Analysis: a Tailings Dam Case Study

摘要

One of the greatest challenges in performing 3D geotechnical numerical analysis is in creating a model of the geometry of a particular site. A well-defined model that accurately represents the site topography and boundaries of material layers is essential to producing an accurate analysis. For a site with few material units in which the units are cleanly separated and stacked on top of each other, the modelling process is relatively simple. However, sites may have numerous features such as dykes, ore bodies, or other enclosed volumes of material with complex shapes. The Material Volume Meshes (MVM) is used to handle unusual layered models in situations where the traditional methods present several limitations, as the most common cases like surfaces folding over themselves or negative volume layers. The MVM represents one distinct volume of material composed by a closed mesh shape and any material assigned. Such a material volume could therefore be subsequently represented by a rock or undrained/drained soil constitutive model. The MVM is fully independent and over-rides the layer-cake conceptual model and respects the region boundaries of the model volume during the slope stability analysis. This paper seeks to demonstrate a case study of a 3D tailings dam numerical model developed using material volume meshes as a starting point for a slope stability analysis. A conceptual model was first developed and then imported directly to a 3D limit equilibrium method (LEM) slope stability software package. The results showed how MVMs can help in obtaining a realistic factor of safety representative of complex geological subsurfaces. The paper also aims to illustrate the advantages of a well-defined conceptual model and what type of field information can be utilized to form a material volume mesh for the purpose of creating a reliable model that adequately represents field conditions.