Geology Reference
In-Depth Information
Stage 1: Desk study at project conception stage
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Identi
cation of key geological and environmental hazards at optional sites based on broad desk study
and possibly site visits.
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Consider site constraints, engineering considerations and economic factors.
Stage 2: Detailed desk study and reconnaissance survey
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Collect and review all documents relevant to the preferred site, including topographic and
geological maps, aerial and terrestrial photographs and any previous investigation reports.
Review site history including previous building works and mining. Look for hazards such as
landslides.
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Site mapping, possibly with advance contract allowing safe access, vegetation clearance and trial pits
or trenches.
The Preliminary Ground Model
Develop a preliminary geological and geotechnical working ground model that can be used as a
reference for the rest of the ground investigation.
This preliminary model should be used as a reference by all the team, including those logging
boreholes and trial pits. The loggers need to knowwhat to expect and to be able to identify anything
that necessitates revisions to the ground model.
Site-speci
c ground investigation should be aimed at verifying the model, answering any
unknowns and allowing design parameters to be derived.
Stage 3: Preliminary ground investigation linked to basic engineering design
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Consider use of geophysical techniques to investigate large areas and volumes.
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Preliminary boreholes designed to prove geological model (rather than design parameters).
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Instrumentation as appropriate (e.g. to establish groundwater conditions and seismicity).
Stage 4: Detailed ground investigation
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Further investigation to prepare detailed ground model and allow detailed design.
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In situ and laboratory testing to establish parameters.
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Detailed instrumentation and monitoring.
Stage 5: Construction
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Review of ground models during construction (including logging of excavations).
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Testing to con
rm design parameters.
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Instrumentation to monitor behaviour and check performance against predictions.
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Revision to design as necessary.
Stage 6: Maintenance
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Ongoing review
e.g. of settlement, slope distortion, groundwater changes and other environmental
impacts, possibly linked to a risk management system.
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