Review of Roof Support Options for Next Generation of Continuous Miner

SCT Operations Pty Ltd have been requested by ACARP roadway development task group to conduct an assessment of roof support options for the next generation of continuous miners (CM). The feasibility of using a canopy-like system to protect the unsupported span of roadway, bolt placement close to the face and impact of an arc roof shape on the stability of roadways are studied in this project. These objectives were investigated by using 3D and 2D numerical modelling. Bulli Seam geological and geomechanical characterisation were used as a representative of a high stress environment.

A brief literature review on behaviour of the roadway close to the face is presented. The 3D numerical modelling was implemented to assess the stable width of unsupported span. The feasibility of using a canopy-like system to provide a stable working area and delay the rock bolt installation was simulated. The modelling showed that the roadway in Bulli Seam conditions will have unstable roof for unsupported span with a width of more than 4m.

An arbitrary canopy geometry and installation were chosen and the effectiveness of it under various support pressure was numerically studied. It was found that the canopy-like system is able to provide confinement to the roof rocks and does limit the roof deformation. The chosen geometry for canopy decreases the roof displacement significantly.

The impact of bolt placement close to the face on the stability of the roadway was also assessed by numerical simulation. It was proven that reducing the unsupported span by bolt placement 1m behind the face significantly improves the stability of roof. The impact of bolt replacement close to the face is similar to the effectiveness of the canopy-like system.

In last section of this project, effectiveness of arc roof shape to improve the stability of the roadway was studied by 2D numerical modelling. This simulation show that the arc roof shape does not significantly improve the stability a roadway excavated in Bulli Seam. Considering the operational difficulties of arc roof excavation, it is not recommended for Bulli Seam conditions.