TECHNICAL MEETING AND LUNCHEON: Tuesday, February 16, 2016

Where: The Petroleum Club of Lafayette

When: 11:30am

Lunch: $20.00 for members ** Be Sure to Bring Your 2015-2016 Membership Dues!**

Luncheon Talks:  

Soil-type estimation beneath a coastal protection levee, using resistivity and shear wave velocity.

By: Juan M. Lorenzo


Unconsolidated Holocene deltaic sediments comprise levee foundation soils in New Orleans, USA. Whereas geotechnical tests at point locations are indispensable for evaluating soil stability, the highly variable sedimentary facies of the Mississippi delta create difficulties to predict soil conditions between test locations. Combined electrical resistivity and seismic shear wave studies, calibrated to geotechnical data, may provide an efficient methodology to predict soil types between geotechnical sites at shallow depths (0- 10 m).
The London Avenue Canal levee flank of New Orleans, which failed in the aftermath of Hurricane Katrina, 2005, presents a suitable site in which to pioneer these geophysical relationships. Preliminary cross-plots show electrically resistive, high-shear-wave velocity areas interpreted as low-permeability, resistive silt. In brackish coastal environments, low-resistivity and low-shear-wave-velocity areas may indicate both saturated, unconsolidated sands and low-rigidity clays.

Author Bio:

Juan M. Lorenzo graduated as a geologist from the University of Barcelona in 1983.  The following year he came to the US as a Fulbright student and concentrated on Marine Seismology for his Ph.D. (1991) dissertation at Columbia University.  Since then he has participated in 7 marine geophysical and drilling cruises and led two land-based seismic experiments in central and northern Chile: in 2001, 2007-8.
Currently he uses land- and laboratory-based seismic experiments to research physics models for unsaturated soils (New Orleans levees), the dynamics of shallow faulting (Gulf Coast of Mexico), and microearthquake source mechanics of crack-fault interactions.

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