A focus on improving safety and performance, and reducing the risks associated with shaft excavation is always a key component of our approach. Our shaft team have assessed shafts from 0.9m to 12m in diameter, with depths up to 1400m.  

The greatest unknowns in any shaft excavation program, and those which are likely to have the most dramatic effect on performance and cost are the geotechnical and hydrological conditions in the region of the shaft. We tailor our shaft engineering evaluations to suit our client’s requirements, from scoping studies through to detailed design and construction documentation. 

pitt&sherry’s shaft engineering team have worked for both mine owners and shaft excavation contractors. Our on-ground experience in the excavation phase of shaft projects has enabled us to refine our shaft assessment and design capabilities. 

Shaft planning services

We provide a full range of upfront work for shaft development projects including development planning, site investigations and geotechnical assessments such as:

• Mine scale shaft location assessments:
  • Topographic mapping and survey – Interpretation of aerial photographs
  • Geotechnical mapping
  • Geophysical studies
• Regional and mine scale structural geology modelling
• Regional hydrogeological assessments
• Mine scale numerical modelling
• Stress and subsidence assessments
• Preliminary excavation method and support assessments
• Project risk assessments.

Shaft site investigations

A full range of shaft site investigation field services is available to our clients from engagement of drilling contractors, drilling supervision, core logging, boxing and sample selection, geophysical investigations, and packer testing such as:

• Hoisting shafts
• Ventilation shafts
• Ore passes
• Coal bins
• TBM access shafts
• Pump station shafts
• Shafts in hard rock, soft rock and soils
• Coal mine shafts
• Metalliferous mine shafts
• Geotechnical and hydrogeological assessment.

We use multiple empirical and analytical methods to undertake geotechnical and hydrogeological assessments for shaft projects, including:

• Structural geology modelling
• Rockmass classification techniques
• Kinematic wedge analysis
• Stress analysis
• Convergence / confinement analysis
• Hydrogeological modelling
• Assessment of seismicity.

Method selection & design

We offer interpretation of geotechnical and hydrogeological assessment yield information for shaft excavation method selection and support including:

• Shaft collar and presink design
• Headframe foundation design
• Raise bore or blind borer foundations
• Short term and long-term wall stability
• Face stability for raise boring methods
• Drillability, cutter wear and penetration rate assessments
• Ground improvement techniques
• Assessment of squeezing
• Water management:
  – Grouting
  – Water rings
  – Dewatering bores
  – Face pumping
• Temporary and permanent support systems
• Liner design and specifications
• Shaft excavation risk assessment.