US Army Corps of Engineers

BUILDING STRONG®

GEOPHYSICS FOR GEOTECHNICAL ENGINEERS - BRIDGING THE GAPRamanuja Chari Kannan PE FASCE

CESWF-EC-D

June 15, 2011

Atlanta, GA

EVOLUTION OF GEOLOGY

The earliest writing on Geology probably dates back to Theophrastus (372-287BC) who wrote a book on rocks called ‘Peri

Lithion.”Abū Rayḥān al-Bīrūnī was perhaps the first person to document his observations about the earth and is credited with writing the first book on Geology. (A crater on the moon and the University in Tashkent are named after him).

Will Durant in his History of Civilization recognized that al-Biruni worked on the hypothesis that the earth was a sphere, revolved around the sun and spun on it axis.

The term “geology” was introduced by Jean-Andrè Deluc in 1778.William Smith (1769-1839) produced the first geological map of England and Ireland.

GEOLOGY TODAY

Earth science

Economic geology

Mining geology

Petroleum geology

Engineering geology

Environmental geology

Geoarchaeology

Geochemistry

Biogeochemistry

Isotope geochemistry

Geochronology

Geodetics

Geography Geological modeling Geometallurgy Geomicrobiology Geomorphology Geomythology Geophysics Glaciology Historical geology Hydrogeology Meteorology Mineralogy Oceanography

Marine geology

Paleoclimatology Paleontology

Micropaleontology Palynology Petrology Petro physics Plate tectonics Sedimentology Seismology Soil science Pedology (soil study) Speleology Stratigraphy Biostratigraphy Chronostratigraphy Lithostratigraphy Structural geology Volcanology

GEOTECHNICAL ENGINEERING

The credit for understanding of the concept of soil as an engineering material should rightfully belong to Coulomb, who soon after his graduation in 1761 used his knowledge of mechanics to apply to pressure exerted by soils.

Karl Terzaghi of course has been credited with not only coining the term soil mechanics, but also with realizing the importance of understanding geology in understanding soil physical properties. As the saying goes, the rest is history – of soil mechanics. No one is really sure when and why the term Geotechnical Engineering came to absorb soil mechanics, foundation design and anything else that has the word “soil” in it. Terzaghi’s wife Ruth, a geologist and his graduate student and Arthur Casagrande should be credited with connecting mechanics with the material.

MERGING GEOLOGY AND GEOTECHNICAL ENGINEERING

• Geology and Geotechnical Engineering merge in many areas – soil and rock physical properties, site characterization, mineralogy and foundation design.

• While Geotechnical engineers have refined their laboratory testing, in-situ testing and design techniques, the amalgamation of geophysics and geotechnical engineering has not taken a significant role in the practice of geotechnical engineering.

• Geophysical methods should be the primary investigative tool for geotechnical engineers.

GEOPHYSICAL METHODSMETHOD MEASURED PARAMETER

Ground Penetrating Radar (GPR) Dielectric Constant (indicate the top of rock surface)

Electromagnetic Frequency and Time Domain (EFT)

Electrical Conductivity (lateral variation in soil and rock; differentiate soil types including contaminated soils)

Very Low Frequency (VLF) ER Electrical Resistivity (apparent resistivity)

Electrical Resistivity / Capacitively Coupled Resistivity

Electrical Resistivity (stratification/spacial differentiation)

Spontaneous Potential (SP) Electrochemical and Streaming potential (Seepage)

Seismic Refraction Seismic velocity, shear modulus (rock rippability)

Seismic Reflection Seismic velocity (Stratigraphy)

Surface Wave Analysis Seismic velocity, dispersion (S-wave/stratigarphy, karst features)

Microgravity Density (bedrock/karst)

Magnetic Potential Magnetic susceptibility (minerals, buried objects)

Thermal Imagery Surface temperature (seepage, karst)

Radio-metrics Natural Gamma Radiation (ores, fracture)

Cross-hole tomography Subsurface profiling, stratigraphy (karst)

GEOPHYSICS FOR GEOTECHNICAL ENGINEERS

• Policy Development• Recruitment and Training• Data management and analysis• Risk Assessment and Mitigation• Consultation and Technical Reviews• Quality Assurance• Periodic Inspection and Periodic Assessment

Support

RMC’s PROGRAM

• Develop 1-, 5-, 10-, and 30-year infrastructure investment plans

• Prioritize Issue Evaluations, Dam Safety Modification Reports, and Construction

• Monitor progress and project management for dam safety projects

• Support Senior Oversight Group and HQ efforts to manage funds and queues

HOW WE CAN SUPPLEMENT RMCRMC’s CURRENT CONCERNS OUR RESPONSE AND POTENTIAL

Dam Safety Regulation and Procedures need to define RMC Role

SWF has involved RMC in our DSMS RMC’s role is evolving as we progress

Geotechnical Issues dominate the Portfolio

SWF has one of the strongest staff support and expertise in this area

Risk Based Evaluation is needed SWF has the need to focus in this direction

Organizational Improvement needed We have expertise gathered from CoS, Border Protection, Force Protection, LEED and Design experience

Experienced Staff is Scarce We have surplus capacity from time to time and have a recruiting advantage

Extensive outsourcing to A/E firms SWF has the potential to reduce A/E outsourcing

Prioritizing and Implementation SWF is lower in priority as compared to NE and NW

A PLAN FOR SWF’s RMC PROGRAMWithin the first 30 days:

Establish and staff the centerDefine roles and develop Position DescriptionsDevelop a 1-year and 5-year budgetEstablish program priorities

Within the first 90 days:Internal Recruitment and assign responsibilities for the internal

teamPrioritize projects and develop schedules (primarily DSMS and LRP

projects)Match national resources and develop talent poolDetailed budgets for DSMS and LRP and funding support

SWF’s RMC PROGRAM PLANWithin the first 1 year:

Get project teams working on specific DSMS and LRP projectsAssist the Levee CoP in developing LSMS methodsDevelop detailed 5-year design plan for DSMS and LSMSDevelop Remedial action plans and construction plansWrite contracts for remedial works – standardize if possible

Within the first 5 years:Set up Inspection Plans based on risk evaluationAssist Dam and Levee CoPs to develop practice standardsDocument strategies from lessons learnedIdentify10-year and 60-year needs and needed infrastructure

improvements.

THANK YOU