Required Information for Structural Evaluation |
Non Destructive Testing Techniques |
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Schmidt hammer |
Single flatjack |
Double flatjack |
In-plane shear |
Modified shear test |
Ultrasonic pulse |
Mechanical pulse |
Magnetic method |
Visual |
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Material Properties |
Compressive strength (direct) |
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usefull |
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Compressive strength (indirect) |
usefull |
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usefull but not enough |
usefull but not enough |
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Deformability |
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usefull |
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Joint shear strength |
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usefull but not enough |
usefull |
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Coulomb shear relationship |
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usefull |
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Condition |
voids between wythre |
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usefull |
usefull |
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cracks in outer wythes |
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usefull but not enough |
usefull but not enough |
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usefull but not enough |
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In-situ Stress |
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usefull |
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material uniformity |
usefull |
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usefull |
usefull |
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usefull but not enough |
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location of reinforcement |
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usefull |
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Borehole Surveying Devices |
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Device |
Measurement obtained |
Primary Use |
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Spontaneous potential (SP) |
Natural voltages betweens fluids in materials of dissimilar lithology |
Differentiating between sands and clays |
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Single-point resistivity |
Resistance of rock adjacent to hole |
with SP log provides good indication of subsurface stratification and soil type |
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Multiple-point resistivity |
Resistivity of formations |
Determination of mud infiltration and effective porosity |
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Radiation logging |
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Gamma |
natural gamma radiation of materials |
identification of clay seams, location of radioactive tracers, with SP & resistivity logs provides information on relative porosity |
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Neutron |
hydrogen atom concentration |
determination of moisture content content and porosity belowzone of saturation porosity |
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Gamma-gamma |
gamma radiation absoprtion |
correlates with bulk density and useful to determine porosity if grain specific gravity is known |
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Sonic logging |
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Acoustic velocity |
travel time of primary and shear wave velocities |
with calipher and density logs determine dynamic elestic & shear moduli of in situ rock |
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Acoustic imagery |
reflected acoustic energy |
locate fractures, voids, strike, dip of joints, faults, bedding planes, etc. |
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Fluid logging |
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Temperature |
Temperature gradient |
Determine geothermal |
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Fluid resistivity |
electrical resistance of borehole fluids |
with temperature data the determination of disolved solids locate zones of waters loss or gain |
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Trace ejector |
controlled ejection of trace elements |
groundwater flow patterns |
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Fluid sampler |
borehole or formation fluid from predetermined depths |
uncontamined samples for waters quality studies |
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Visual logging |
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Borescope |
visual image of sidewalls to depths of 30m or less, eriscopic tool |
cheap, rapid examination of borehole walls |
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Borehole camera |
photographs of 360° sweep at right angles to the wall, overlapped |
Examination of borehole conditions, bedding, joints, etc. |
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Downhole camera |
photographs of sidewalls takn from bottom of camera, several feet of hole |
examination of borehole conditions, beldings, joints, etc. |
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Borehole television |
image of the sidewalls displayed at the time of exposure on a surface monitor |
rapid examination of borehole conditions as the device is lowered or raised |
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Miscellanous logging caliper |
borehole size |
washouts, fractures, etc. needed for interpretation of other logs |
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Borehole surveyor |
downhole directional survey |
precise location and attitude of features recorded on other logging tools |
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Effectiveness of Cavity Investigation Techniques |
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Cavity type |
increased borings |
geophysics |
remote sensing |
piezometers |
pump - dye flow tests |
discontinuity analysis |
borehole cameras |
mine record studies |
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Anhydrite Gypsum |
poorly effective |
not effective |
poorly effective |
not effective |
not effective |
effective |
not effective |
poorly effective |
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Karst |
highly effective |
very effective |
very effective |
poorly effective |
effective |
highly effective |
highly effective |
not effective |
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Salt |
poorly effective |
effective |
effective |
not effective |
not effective |
not effective |
poorly effective |
effective |
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Mines |
very effective |
very effective |
very effective |
not effective |
not effective |
not effective |
highly effective |
highly effective |
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Lava tubes |
very effective |
poorly effective |
very effective |
poorly effective |
poorly effective |
not effective |
effective |
not effective |
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