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 servicesWe 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 photographsGeotechnical mappingGeophysical studiesRegional and mine scale structural geology modellingRegional hydrogeological assessmentsMine scale numerical modellingStress and subsidence assessmentsPreliminary excavation method and support assessmentsProject risk assessments.Shaft site investigationsA 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 shaftsVentilation shaftsOre passesCoal binsTBM access shaftsPump station shaftsShafts in hard rock, soft rock and soilsCoal mine shaftsMetalliferous mine shaftsGeotechnical and hydrogeological assessment.We use multiple empirical and analytical methods to undertake geotechnical and hydrogeological assessments for shaft projects, including:Structural geology modellingRockmass classification techniquesKinematic wedge analysisStress analysisConvergence / confinement analysisHydrogeological modellingAssessment of seismicity.Method selection & designWe offer interpretation of geotechnical and hydrogeological assessment yield information for shaft excavation method selection and support including: Shaft collar and presink designHeadframe foundation designRaise bore or blind borer foundationsShort term and long-term wall stabilityFace stability for raise boring methodsDrillability, cutter wear and penetration rate assessmentsGround improvement techniquesAssessment of squeezingWater management: – Grouting – Water rings – Dewatering bores – Face pumpingTemporary and permanent support systemsLiner design and specificationsShaft excavation risk assessment.