Exploration & Testing Flashcards
What is the value in using a Pressuremeter during exploration? What soil types is it usable in?
Subgrade modulus (k-value), stress-strain modulus & undrained shear strength / CBR
Soft rock, sand, silt and clay
What is the value in using GPR?
Detecting voids/objects, GW, and soil/bedrock interface
What soil types is GPR good for? What soil types is it not good for?
Good in sand/rock to about 50 ft depth
Clay can limit penetration to a few feet
What is the use of Electrical Resisitivity?
Assessing corrosion potential of buried steel and determining the groundwater surface
What is the use of Seismic Refraction?
Determining depth, thickness, and shear wave velocity of subgrade layers
What two design standards have information about site characterization?
1) FHWA NHI-16-072 GEC No. 5 - FHWA Geotechnical Site Characterization
2) FHWA NHI-06-088 - FHWA Soils and Foundations Reference Manual
What value does the Packer Test provide?
Hydraulic conductivity / permeability
What value does the Plate Load Test provide?
k-value, can be used on rock
Bearing Capacity
What value does the Seismic Cone Penetrometer provide?
Stress-wave measurements
Shear Wave Velocity
What value does the Field Torvane Test provide?
Undrained shear strength, Su
What soil conditions is the Becker Hammer Penetration test good for?
Lots of cobbles and boulders
Equation for RQD
Sum of pieces greater than 4 inches divided by the total core run length
What are examples of undisturbed sampling methods?
Shelby Tubes, California Tube, Thin-walled piston, block sampling
What are field methods to estimate shear strength parameters like angle of shearing resistance and cohesion?
- SPT
- CPT
- DMT (flat plate dilatometer)
- PMT (pressuremeter)
- VSA (vane shear)
What are lab methods to estimate shear strength parameters like angle of shearing resistance and cohesion?
- Direct Shear Test
- Triaxial Test
- Unconfined Compression Test
