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List of products by author: B. Ashcroft
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Hard Rock TBM v . Soft Ground Fault - A case study in the Himalayas
Abstract: Twin 8.5 m diameter, 10.5 km long parallel headrace tunnels under overburdens of up to 1 870 m with high horizontal stresses were excavated for the Neelum Jhelum Hydroelectric Project located in the Azad Kashmir region of northeast Pakistan using two main beam gripper Tunnel Boring Machines (TBMs). The TBMs were introduced to improve tunnel excavation rates and were the only realistic...
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Practical Considerations for Designing Rock Support for Tunnel Linings in Open Gripper TBMs
Abstract: Tunnelling can be said to unite theory and practice into its own construction art. With this in mind, it is impossible for designers of tunnel linings to disassociate themselves from the practical construction aspects of excavation and installation of support. This paper provides guidance for designers of rock support and linings for tunnels excavated with hard rock open gripper Tunnel Boring...
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Reinforced Concrete Tunnel Junctions: Design and Construction Guidelines
Abstract: Whilst junctions between a tunnel and another tunnel, shaft, or other underground structure typically account for only a small proportion of the total length of a tunnelling project, their design and construction invariably present significant challenges. These challenges manifest themselves during the excavation and the installation of both the initial and permanent support. While many...
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Reinforced Concrete Tunnel Junctions: Design and Construction Guidelines
Abstract: Whilst junctions between a tunnel and another tunnel, shaft, or other underground structure typically account for only a small proportion of the total length of a tunnelling project, their design and construction invariably present significant challenges. These challenges manifest themselves during the excavation and the installation of both the initial and permanent support. While many...
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Severe Rockburst Event – TBM Recovery - A Case Study
Abstract: Twin 8.5 m diameter, 10 km long parallel headrace tunnels under overburdens of up to 1 870 m with high horizontal stresses were excavated for the Neelum Jhelum Hydroelectric Project located in the Azad Kashmir region of northeast Pakistan using two main beam gripper Tunnel Boring Machines (TBMs). Both TBMs started headrace tunnel excavation in early 2013 with completion by the first TBM in...
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Short-Term Rockburst Prediction in TBM Tunnels
Abstract: Rockbursts in the tight confines of a TBM tunnel can be highly hazardous events given the proximity of vital equipment and workers to the rockburst source, and the space constraints that severely limit employment of countermeasures. Consequently, the ability to predict rockbursts with some measure of confidence as excavation proceeds (i.e. in the ‘short-term’) is critical to the safety of both...
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