[pdf-1,pdf-2] Lorenzo, J.M., Goff1, D., Hayashi, K., 2016. Soil-type Estimation Beneath a Coastal Protection Levee, Using Resistivity and Shear-wave Velocity. 22nd European Meeting on Environmental and Engineering Geophysics, Sept. 7, 2016. 11.10 am. Engineering Geology and Geotechnical Investigations III. Barcelona, Rm B 22.

Lorenzo, Juan M., Goff1, Derek., Hayashi., K., 2016. Soil-type estimation beneath a coastal protection levee, using resistivity and shear wave velocity. Symposium on the Application of Geophysics to Environmental and Engineering Problems. Mar. 24, 2016. 4.30 – 5.00 pm. Denver, , Marriott City Center, Penrose 2..

[pdf] Lorenzo, J.M. , Goff1, D., Hayashi, K. 2015. Combined resistivity and shear wave velocity Soil-type estimation beneath a coastal protection levee.   Eos Trans., AGU, San Francisco,  14-18 December, Fall Meeting. Abstract NS51A-1968  Friday, Dec. Frid,. 18 8.00 am-12.20 pm Moscone A-B.

Omale1, A. P., Lorenzo, J.M. 2015. Using Fault kinematics to evaluate the relationship between Cenozoic Fault Activity, sedimentation rates and salt movement in the Gulf of Mexico. A comparison between southwest and southeast Louisiana.  Presentation to the Association of Levee Boards of Louisiana, 2 December,  Marriott Hotel, New Orleans.
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 [pdf] Goff1, D., Lorenzo, J.M. (invited), Hayashi, K. 2015.  Resistivity and shear wave velocity as a predictive tool of sediment type in coastal levee foundation soils.   Summit on levees and Dams, SEG Technical Workshop.
Friday , Oct. 23.

[pdf] Omale1, A. and Lorenzo, J.M.  2015 Using Fault Kinematics to Evaluate the Relationship between Cenozoic Fault Activity, Sedimentation Rates and Salt Movement in the Gulf of Mexico- A Comparison Between Southwest and Southeast Louisiana Annual 65th Convention of the GCAGS Sept. 20-22, Houston, 9.25 am. Sept. 21.

 [pdf] Goff1, D., Lorenzo, J.M., Hayashi, K. 2015. Resistivity and shear wave velocity as a predictive tool of sediment type in coastal levee foundation soils.  Symposium on the Application of Geophysics to Engineering and Environmental Problems 2015: 167-176.

Goff1, D., Lorenzo, J.M. 2015 Resistivity and shear wave velocity as a predictive tool of sediment type in coastal levee foundation soils. Presentation to the Association of Levee Boards of Louisiana in a joint effort with Coastal Protection and Restoration Authority, Department of Transportation and Development, March 2015 Marriott Hotel, Baton Rouge.


[pdf]Lorenzo, J.M. 2015 An Objective Approach to Strategic Monitoring of the Mississippi River Levee System. Presentation to the Mississippi River Commission , Baton Rouge, March 27 2015.

[pdf] Lorenzo, J.M., Crane1, J.M.,  Shen1,  2013. Controls of stress and water saturation on in-situ Q for shallow (< 1 m), unconsolidated sand. Eos Trans., AGU, San Francisco, 9-13 December, Fall Meeting. Abstract NS41A-1778.

[pdf] Shen, J. Crane, J. Lorenzo, J. White, C.A 2013 Constitutive elastic models to predict shallow (<30m)  seismic velocities: Natural soils beneath an earthen levee: Marrero, Louisiana, U.S.A.  SEG Technical Program Expanded Abstracts 2013, 5221-5222, doi:10.1190/segam2013-1489.1 Friday 27 September.

[pdf] Crane, J., Lorenzo, J., Shen, J. and White, C. 2013. Seismic velocity prediction in shallow (< 30m)partially-saturated, unconsolidated sediments using effective medium theory. Symposium on the Application of Geophysics to Engineering and Environmental Problems 2013, 553-565 Denver CO., March 17-22.
 
[pdf] Lorenzo, J. M. 2011 Shallow (0-10 m) seismic investigation of a distressed earthen levee, New Orleans, USA. Symposium on the Application of Geophysics to Engineering and Environmental Problems 2011: 388.2011 Charleston, SC. S21: Earthen Dams and Levees: Geophysical Reconnaissance, Exploration, and Monitoring Wednesday, April 13 Room 3, 273-S21[pdf] Shen, J. Crane, J. Lorenzo, J. White, C.A 2013 Constitutive elastic models to predict shallow (<30m) seismic velocities: Natural soils beneath an earthen levee: Marrero, Louisiana, U.S.A.  SEG Technical Program Expanded Abstracts 2013, 5221-5222, doi:10.1190/segam2013-1489.1 Friday 27 September.

ID#

NS41A-1507

Location:

MS-Poster Hall (Moscone South)

Time of Presentation:

Dec 16 8:00 AM - 12:20 PM

 AGU Meeting-2010 San Francisco

A new impulsive seismic shear wave source for near-surface (0-30 m) seismic studies
J. M. Crane1; J. M. Lorenzo1
1. Geology and Geophysics, Louisiana State University, Baton Rouge, LA, United States.

 

Estimates of elastic moduli and fluid content in shallow (0-30 m) natural soils below artificial flood containment structures can be particularly useful in levee monitoring as well as seismic hazard studies. Shear wave moduli may be estimated from horizontally polarized, shear wave experiments. However, long profiles (>10 km) with dense receiver and shot spacings (<1m) cannot be collected efficiently using currently available shear wave sources. We develop a new, inexpensive, shear wave source for collecting fast, shot gathers over large acquisition sites.

In particular, gas-charged, organic-rich sediments comprising most lower-delta sedimentary facies, greatly attenuate compressional body-waves. On the other hand, SH waves are relatively insensitive to pore-fluid moduli and can improve resolution. We develop a recoil device (Jolly, 1956) into a single-user, light-weight (<20 kg), impulsive, ground-surface-coupled SH wave generator, which is capable of working at rates of several hundred shotpoints per day.

Older impulsive methods rely on hammer blows to ground-planted stationary targets. Our source is coupled to the ground with steel spikes and the powder charge can be detonated mechanically or electronically. Electrical fuses show repeatability in start times of < 50 microseconds. The barrel and shell-holder exceed required thicknesses to ensure complete safety during use. The breach confines a black-powder, 12-gauge shotgun shell, loaded with inert, environmentally safe ballast. In urban settings, produced heat and sound are confined by a detached, exterior cover. A moderate 2.5 g black-powder charge generates seismic amplitudes equivalent to three 4-kg sledge-hammer blows.

We test this device to elucidate near subsurface sediment properties at former levee breach sites in New Orleans, Louisiana, USA. Our radio-telemetric seismic acquisition system uses an in-house landstreamer, consisting of 14-Hz horizontal component geophones, coupled to steel plates. Reflected, refracted and surface arrivals resulting from a single shot of this seismic source are comparable in signal, noise, and frequency composition to three stacked hammer blows to a ground-planted stationary target.

Contact Information
James M. Crane, Baton Rouge, Louisiana, USA, 70809-0000, click here to send an email



ID#

NS33A-04

Location:

2016 (Moscone West)

Time of Presentation:

Dec 16 2:25 PM - 2:40 PM
 

AGU Meeting-2009 San Francisco

Shallow (0-10 m) seismic investigation of a distressed earthen levee, New Orleans, USA.
J. M. Lorenzo1; J. Hicks1; E. E. Vera2
1. Geology and Geophysics, Louisiana State University, Baton Rouge, LA, United States.
2. Departamento de Geofísica, Universidad de Chile, Santiago, Chile.

 

Both deep- and near-surface hydrogeologic processes can contribute to the structural failure of artificial earthen levees. Recently, seismic geophysical methods have attempted to develop a proxy for engineering shear strength, by mapping changes in the transmission velocity of shear waves. High fluid content may indicate both weak, under-compacted materials and/or organic-rich sediments. In the absence of electromagnetic methods, Vp/Vs ratios can be used as good indicators of variations in the fluid (water, and air or gas) saturation. Cone penetration borehole tests measure the resistance of soils to penetration of the cone tip and its frictional sliding that can be correlated to sediment types and their physical properties.

A distressed section of an artificial earthen levee, suitable for seismic investigation, lies ~15 km S of the city of New Orleans, Louisiana, USA. Open curvilinear fissures, 10 cm wide, 30 cm deep, and up to 100 m in length, exist along the crest at two sites. Between September 2007 and February 2008 we collect horizontally (SH) polarized shear and compressional wave (P) data in pseudo-walkaway tests for the upper 100 m of the subsurface along the protected (west) side of the earthen levee, within 30 m of its crest. One profile lies parallel and adjacent to the damaged levee crest and, for reference, two profiles lie nearby adjacent to undamaged portions of the artificial earthen levee.

In the first ~30 m of sediment below the lower delta plain of the Greater New Orleans area, a complex and dynamic interaction of freshwater and marine sedimentary environments juxtaposes a diverse set of facies. We combine of Vp and Vs velocity maps, sedimentary environment interpretations, and cone-penetration-derived sediment/soil and laboratory-derived physical properties to locate possible zones of high fluid concentration, (and perhaps seepage), weak engineering materials, and natural foundation soil shear strength.

Under the distressed portion of the earthen levee, shear modulus minima in a constructed profile, correlate with zones of estimated high saturation porosity (80%) high organic content and undercomapcted clay-rich sediments. We interpret that despite nominal full soil saturation, small in-situ intergranular, free gas maintains Vp values low (~140 m/s). However, Vp/Vs ratios increase to values > 14 within gas-free sands of the underlying St. Bernard delta lobe complex (2000 -4000 yr) at shallow depths (~ 5m).

Contact Information

Juan M. Lorenzo, Baton Rouge, Louisiana, USA, 70803-4101, click here to send an email
AAPG Meeting-2010-New Orleans
Shear-Wave Velocity Anomalies (60 m/s) and High Vp/Vs Ratios (>16) at Shallow Depths (0-5m) Below a Distressed Artificial Levee, Marrero, Louisiana, USA
AUTHORS (FIRST NAME, LAST NAME): Juan M. Lorenzo1, Jason Hicks1, Emilio E. Vera2
INSTITUTIONS (ALL): 1. Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, United States.
2. Departamento de Geofisica, Universidad de Chile, Santiago , Chile.
ABSTRACT BODY: A growing societal need exists for scientific involvement in the study of coastal protection systems, which can be addressed by near-surface seismic methods. Both deep- and near-surface hydrogeologic processes can contribute to the structural failure of artificial earthen levees.

Recently, attempts have been made at using seismic geophysical methods to develop a proxy for engineering shear strength, by mapping changes in the transmission velocity of shear waves (Vs) through artificial levees. In the absence of electromagnetic methods, Vp/Vs ratios can be used as good indicators of variations in the fluid (water, and air or gas) saturation. Cone penetration borehole tests measure the resistance of the soil to penetration of the cone tip and its frictional sliding that can be correlated to sediment types and seismic physical properties.

A distressed section of an artificial earthen levee, suitable for seismic investigation, lies ~15 km S of the city of New Orleans, Louisiana, USA. Cracks, ~10 cm wide, ~30 cm deep, up to ~100 m in length, and arcuate in plan view, exist along the crest at two sites.

Between September 2007 and February 2008, we collect both seismic reflection and refraction, horizontally polarized, shear (S) and compressional wave (P) data in pseudo-walk-away tests for the upper 30 m of the subsurface along the protected (west) side of the earthen levee, and within 30 m of its crest. One profile lies parallel to the damaged levee crest and, for reference, two profiles run parallel to undamaged portions of the levee.

We integrate P-velocity (Vp) and S-velocity (Vs) maps, sedimentary environment interpretations, and cone-penetrometer-derived-sediment/soil and laboratory-derived physical properties from 10 test sites along the levee crest. We interpret zones of (1) high fluid concentration and perhaps seepage, (2) high-organic content, and (3) variable soil shear strength as a function of sediment facies.

Predicted shear modulus minima correlate with interpreted zones of, high-organic- and undercomapcted, clay-rich sediments. We interpret that despite nominal full soil saturation, small, in-situ intergranular free gas maintains Vp/Vs ratios low. However, Vp/Vs ratios reach values > 16 near saturated gas-free sands, atop a sand- rich buried delta lobe (2000 - 4000 yr) at ~5 m depth under the distressed portion of the earthen artificial levee.
KEYWORDS: near surface geophysics, seismology, hydrogeophysics, environmental geophysics.

SESSION DAY: April 13, 2010
SESSION ABSTRACT START TIME: 8:30 AM
SESSION TITLE: Theme IX: Environmental Impact