P49 Counter Weight Tower – George Fisher Mine

TEG Consulting Engineers was tasked with the design of the George Fisher Mine P49 Counter Weight Tower, as steel access tower that cantilevers off the inside of the P49 vertical lift shaft.

Glencore required this tower for providing maintenance access to the counter weights as six levels, as well as access to a remote platform and bridge to change pully wheels.

The Tower is to be fixed to the circular wall of the P49 lift shaft via rock anchors into the concrete wall.

The access tower had the following parameters:

1. All levels to be able to access counter weight mechanism.
2. Be completely suspended from the shaft curved wall.
3. Be able to withstand all trafficable loadings and wind loading due to wind turbulence in the shaft.
4. Provide a safe work access to the tower, minimal movement. Bracing face restricted on counter weight side as needs to be clear for counter weight access.
5. Top level to have a 200kg SWL monorail crane attached. And lift hatch to have guide wires to prevent equipment from moving outside of lift alignment.

TEG Consulting Engineers (TEGCE) was responsible for all engineering design and documentation as well as providing fabrication drawings of all components.

The model was designed and modelled using Autodesk Inventor and analysed for stress using the FEA module in the program, along with hand checks to check for deflection and stress points.

The assembly of the tower is restricted to small cranage and manual handling so most the components are required to be bolt assembled.

Because the P49 Counter Weight Shaft Access Tower was required to be retro fit amongst existing infrastructure.

A number of challenges presented themselves:

1. Conflict with counter weight frame, whilst still maintaining access to the counter weight for maintenance.
2. Avoiding clash with shaft framing and service ducting fastened to all.
3. Achieving a robust structure that minimises deflection and movement within standard tolerances.
4. Achieving a structure that can be assembled using bolted connections to minimise hot work in the shaft.
5. Inclusion of adjustments to levels as part of variation work.
6. Inclusion of additional platform with underslung monorail and lift hatch.
7. Inclusion of remote access platform and retractable bridge for access to counter weight pullies.

Initial Engineering design was completed in required timeframe and satisfied stakeholders and regulators. Additional design requirements due to requested change in levels and requirement for additional platform level and addition of monorail crane and remote platform access via retractable bridge. Achieved and submitted for construction.