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FHWA Unknown Foundations Summit
Unknown Subsurface Bridge Foundation Testing for Depth Determination Larry Olson, President, Olson Engineering
Unknown US Bridge Foundations
Unknown Foundation Surface NDE Methods
Get the depth of it, not going to see surface of piles. Periodic echoes visible in data. Impulse response also resonated because there are multiple modes of resonation.
Bending Waves method
As hit it vertically and watch go down and back, hoping to see reflections here. Concluded that 23 ft was a material change.
Ultraseismic testing in NC.
Borehole NDE methods
Parallel Seismic method
Concrete pile pier, old Bastrop bridge
Coors Bridge, highway 58, made interesting case study for research. Dominated by 2 waves. Will see lot of energy go from footing into the ground. Caused tube wave go up/down, indicates tip.
Length Determination of Timber Piles with Parallel Seismic xxx [railroad bridge in California]
Induction method for steel piles.
No strong magnetic field when go beyond tip.
Borehole radar method, won't see much of reflection for radar, sometimes.
Induction field, 1 site worked, 1 didn't
Combine parallel seismic When push cone in can learn something about soil. Getting cone data, strength of soil, etc.
Data examples of energy and cone measurement. Weaker and slower
Can give info when want to
Faster, more economical testing than with borings fro PS test.
Q: PS is above 90 percent accuracy, 95 in real world. Borehole method is higher. When soils stiffer may fall off or not see bottom echo. [statement, no response]