Geotechnical Data collection and analysis Flashcards
What areas are is exploration information gained
means geological, geophysical,
geochemical, sampling, drilling, trenching, analytical
testing, assaying, mineralogical, metallurgical and other
similar information concerning a particular property that
is derived from
– activities undertaken to locate, investigate, define or
delineate a mineral prospect or mineral deposit
what are the 6 data collection methods
- Preliminary
- geophysical investigation
- Geotechnical drilling and core investigation
- Exposure mapping
- Arial photogrammetric techniques
- Laboratory and field testing and measurements
What are examples of Geophysical investigation and testing methods
Seismic reflection method
Gravity methods
magnetic methods
Electromagnetic wave methods
What are GPR waves
GPR waves are sensitive to changes in the subsurface and to GPR data contrasts in electrical and magnetic properties; such changes can be detected, imaged and characterised
What are the rock mechanical properties for geophysical methods
Modulus
Strength
and permeability
What are geophysical methods based on
rock physical and mechanical properties
What in rock density useful for
in estimating in situ stresses and loads on pillars in the tributary area method and so on
What are geophysical methods in pricing compared to drilling
relatively cheap
What does diamond coring provide estimates of
- Lithological boundaries
- Alteration
- Weathering
- Orebody size, shape,
- Grades, continuity
- Geotechnical characteristics
- Hydrology
What are some of the suggested approaches for rock mass characterisation
*Logging a number of holes
*centre of deposit into
*Orebody periphery (outwards bounds)
What is the typical core logging procedure
- core logged and bagged and assayed
- geotechnical information collected
- logging detailed within ore body bondaries
- logging outside bounds
- interpretation and identify structures
What are some of the information gained in geological logging
*header
*depth
*rock material
*degree of weathering
*rock strength estimate
*graphic log
* RQD
*core recovery
What does core drilling provide
gives the opportunity to take core samples for determining physical and rock mechanical properties
What are rock stresses primarily a function of
*overburden weight
*tectonic forces
*boundary conditions
Why do stresses vary locally
*topography
*shearing on structure and contacts
*stiffness
*erosion
*rock temperature
What are examples of where rock stress is experienced
*geological
*boreholes
*underground openings
*earthquakes and mining-induced seismicity
What are the categories of rock stress management
Overcoring, undercoring, hydraulic fracturing and others
What are methods of overcoring
*triaxial stain cells
*borehole deformation gauge
*borehole slotter
*doorstopper
*pin arrays
What are methods of undercoring
*flat jacks
*pin arrays
*under excavation technique
What are other methods
*Acoustic emmisions
*deformation rate analysis
*breakout and drilling-induced fracturing
*analysis of local seismicty
*strain relief
What happens in overcoring
The rock is unloaded by drilling out a large core, the radial displacements are monitored in a central pilot borehole
What is hydralic fracturing
uses pressurised water in a borehole to fracture the rock or re-open fractures in rock
How are breakout location observed
they are aligned with the intermediate principal stress acting in the plane normal to the borehole axis
What can the observational techniques of borehole breakout determine
They can provide a reliable indication of the in situ stress fields
What does water pressure do to groundwater geomechanics
Water pressure reduced the stability of underground excavations though reducing the shear stress, water pressure in near vertical fissures reduce stability.
What can high moisture content lead to
*increase the density of geomaterials with increased transport cost
*accelerated weathering
What can freezing of groundwater cause
*wedging in water filled fissures
*drainage blockage resulting in increased water pressure and reduced stability
