Learning

Software Tutorials

FLAC3D 6.0 Interactive Model Pane

FLAC3D 7.0 Unstructured Mesh Tutorial

A tutorial showing how to create an unstructured mesh in FLAC3D 7.0 using the extruder pane.

FLAC3D 6.0 PFC Plugin Punch

Technical Papers

Neutral mine drainage water-quality impacts from a form taconite mine

Surface waters at the site of a former Minnesota taconite mine were reported to have solute concentrations elevated with respect to water-quality standards.

Packer Testing Program Design and Management

Hydraulic testing using wireline deployed water-inflated packers is becoming a common practice for groundwater characterization at mining sites.

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.