Learning

Software Tutorials

MINEDW Tutorial (Part 4: Meshing)

In this tutorial we will go over meshing, from the creation of a 2D mesh and how to import it to MINEDW, to the inclusion of topography, layers, and pinch-outs to different areas of interest in the model.

MINEDW Tutorial (Part 3: Boundary Conditions)

In this tutorial we will take a look at the different boundary conditions available to the user, and we will go over some examples of different scenarios in which they would be used.

MINEDW Tutorial (Part 2: Visualization Options)

In this tutorial we will explore all the visualization components that MINEDW has to offer, and all the options available to the user to visualize the model's components and properties.

Technical Papers

Caving in the Fabian Orebody —from Mining Stope to Cave Crater in Malmberget

The Fabian orebody is a non-daylighting iron orebody in the LKAB Malmberget Mine in northern Sweden. During 2010, a prognosis of the cave development in the Fabian area was developed, based on compilation and analysis of all available material. In March 2012, a new cave crater formed on the ground surface above the Fabian orebody, similar to what was predicted. The prognosis is compared with observations of the caving and the differences and implications quantified. A program for continued monitoring of mining-induced deformation in Malmberget is also described and a criterion for allowable mining-induced surface deformations is proposed.

Tunnelling and reinforcement in heterogeneous ground – A case study

Abstract

A case study of tunnelling in heterogeneous ground conditions has been analysed. The case involves a tunnel excavated in mixed-face conditions, where the main host material was rock, but for a distance of about 30 m, the tunnel had to be driven through a thick layer of soil, primarily moraine and sandy soil materials.During tunnel drifting, a "chimney" cave developed through the soil layer, resulting in a surface sinkhole.This case was analysed using a three-dimensional numerical model with the FLAC3D software code, in which the soil stratigraphy and tunnel advance were modelled in detail. Tunnel and soil reinforcement in the form of jet grouting of the soil, pipe umbrella arch system, bolting, and shotcreting, was explicitly simulated in the model. The studyaimed at comparing model results with observations and measurements of ground behaviour, and to replicate the major deformation pattern observed. The modelling work was based on a previous generic study in which various factors influencing tunnel and ground surface deformations were analysed for different cases of heterogeneous ground conditions.Model calibration was performed through adjusting the soil shear strength. The calibration provided a qualitatively good agreement with observed behaviour. Calculated deformations on the ground surface were in line with measured deformations, and the location of the tunnel collapse predicted by the model. The installed tunnel reinforcement proved to be critical to match with observed behaviour. Without installed pipe umbrella arch system, calculated deformations were overestimated, and exclusion of jet grouting caused collapse of the tunnel. These findings prove that, in particular, jet grouting of the soil layer was necessary for the successful tunnel advance through the soil layer.

Deep Sublevel Cave Mining and Surface Influence

With increasing depth, higher stress and more difficult mining. With increasing depth is there more ground surface effects or less?