*The geotechnical centrifuge facility at RPI began operation in the
summer of 1989 (see NCEER Bulletin, Vol. 3, No. 3, July 1989). This article
summarizes much of the activity that has taken place in the facility from
that time. For more information about the centrifuge facility, contact Professor
Ricardo Dobry, Director of the Geotechnical Centrifuge Research Center,
Rensselaer Polytechnic Institute, phone: (518) 276-6934; fax: (518) 276-4833;
email: dobryr@rpi.edu or see the web page at www.rpi.edu/~gadrea/centrifuge.html.*

In 1989, NCEER commissioned a geotechnical centrifuge facility at Rensselaer Polytechnic Institute in Troy, New York (RPI). Since then, it has been used in a number of research and engineering projects consisting of about three hundred tests and their interpretation and analysis, performed by dozens of researchers from both RPI and around the world.

The facility contains a 100 g-ton, medium sized centrifuge. The arm of the centrifuge has a total radius of 3 m, and the machine sits in a circular enclosure 7 m in diameter by 3 m in height (Elgamal, Dobry, Van Laak and Nicolas-Font, 1991). It is connected to the soil dynamics laboratory and other geotechnical experimental and computational research facilities occupying about 370 m2 of floor space. This layout was designed to permit easy access and interaction between the centrifuge and the rest of the geotechnical research facilities. In addition, office space is provided for visiting researchers and other centrifuge users.

**Equipment Development and Research**

Since commissioning, there has been a continuous process of equipment and instrumentation development in addition to the research using the centrifuge. Initial projects have focused on failure mechanisms and seismic behavior of reinforced earth walls, liquefaction and lateral spread deformations due to earthquakes in both level and sloping terrain, seismic response and failure of shallow and deep foundations, as well as of retaining walls and earth embankments, comparison of soil improvement and stabilization technologies, static and dynamic friction of geosynthetics, evaluation of long-term performance of landfill construction materials, and modeling of groundwater and contaminant migration.

Equipment development has focused on the data acquisition system, video system for in-flight real time monitoring, equipment for construction of models, measurement transducers, and fabrication of a variety of model containers. In addition, several major equipment items have been developed. The ES-2.2 and ES-18 servo-hydraulic shakers, designed and fabricated at RPI, permit in-flight simulation of earthquake-induced shaking of centrifuge models (Van Laak, Elgamal, and Dobry, 1994a; and Van Laak, 1996). These devices are capable of delivering up to one ton (in the case of the ES-2.2) or up to nine tons (for the ES-18) of dynamic force to a centrifuge model while being spun at up to 100 g on the centrifuge. In order to provide appropriate model boundary conditions for dynamic tests, a flexible-walled laminar box model container, also developed at RPI, is used (Van Laak, Taboada, Dobry and Elgamal, 1994b).

Much of the equipment development and research summarized above has been supported by NCEER. This includes the construction of the ES-2.2 in-flight shaker and the laminar box container for realistic earthquake shaking simulations; and the studies of ground liquefaction and its effects on embankments and shallow and deep foundations, as well as centrifuge studies on the effectiveness of soil improvement measures proposed to mitigate these effects.

**Cooperative Research Efforts**

The activity of the RPI centrifuge has fostered national and international cooperation through contacts and common projects with investigators at other universities and research organizations. This has included centrifuge centers in the U.S. and abroad. Researchers and personnel from the following organizations have spent time at the RPI facility conducting their own model tests, collaborating with the RPI group or participating in centrifuge training courses: Brooklyn Polytechnic Institute, Czech Technical University of the Czech Republic, Hayward Baker Inc., Massachusetts Institute of Technology, National University of Mexico, Tokyo Institute of Technology, Tulane University, University of California/Los Angeles, University of Oklahoma, University of Southern California, University of Washington, and the U.S. Army Corps of Engineers Waterways Experiment Station.

Organizations that have contributed funds to the development of equipment or have sponsored research projects in the RPI geotechnical centrifuge facility include: Air Force Office of Scientific Research; Army Research Office; Bureau of Mines (Czech Republic); Clough Harbour Associates; Erving Paper Co.; Federal Highway Administration; General Electric Co.; Hayward Baker Inc.; International Paper Co.; Kajima Construction Co. (Japan); National Science Foundation; NCEER; INTEVEP (Venezuela); State of New York; U.S. Army Corps of Engineers Waterways Experiment Station; and U.S. Geological Survey.

Tables 1 and 2 summarize the research conducted and illustrate the variety of geotechnical, soil-structure interaction, and geo-environmental problems that have been studied through both static and dynamic model experiments. The first column of each table classifies the tests according to the engineering problem studied. The next column lists relevant publication(s), with the corresponding citation given in the list of references at the end of this article. Column three indicates the type of soil utilized in the project, and column four shows the type of engineering system under study. The next column lists the value or range of values of the centrifugal acceleration, N (g), at which the tests were carried out, and the last column shows the number of centrifuge model tests which produced results for that project.

**Concluding Remarks**

There is no doubt that, in conjunction with similar centrifuge studies done at other organizations, this research at RPI has considerably advanced our understanding of the response of soil and soil-foundation systems to earthquake shaking, especially at large deformations. Calibration of numerical models, development of better quantitative engineering evaluation procedures, and direct evaluation of ground improvement techniques have already started to impact the state-of-practice in earthquake engineering design of new structures and retrofitting of existing facilities. In addition to the specific contributions summarized above and those listed in the tables and corresponding references, NCEER's support for the RPI centrifuge facility and research has proven the usefulness of in-flight centrifuge modeling of earthquake shaking and earthquake forces acting on soil and soil-structure systems, as a very cost-effective and reliable new engineering tool.

**References**

*Abdoun, T., (1994), "Prediction of Soil Deformation Due to Seismically-Induced
Liquefaction," M.S. Thesis, Dept. of Civil Engineering, RPI, Troy,
NY.*

*Abdoun, T., (In Prep.), "Effect of Soil Lateral Spreading Due
to Earthquakes on Pile Foundations," Ph.D. Thesis, Dept. of Civil Engineering,
RPI, Troy, NY.*

*Abdoun, T., Dobry, R., O'Rourke, T.D. and Chaudhuri, D., (1996), "Centrifuge
Modeling of Seismically-Induced Lateral Deformation During Liquefaction
and its Effect on a Pile Foundation," Proc., 6th Japan-U.S. Workshop
on Earthquake-Resistant Design of Lifeline Facilities and Countermeasures
Against Liquefaction, Hamada and O'Rourke (eds.), NCEER 96-0012, pp. 525-539.*

*Adalier, K., (1992), "Post Liquefaction Behavior of Soil Systems,"
M.S. Thesis, Dept. of Civil Engineering, RPI, Troy, NY.*

*Adalier, K., (1996), "Mitigation of Earthquake Induced Liquefaction
Hazards," Ph.D. Thesis, Dept. of Civil Engineering, RPI, Troy, NY.*

*Adalier, K. and Elgamal, A.-W., (1993), "Experimental Results
of Model No. 7," Proc., Int'l Conf. on the Verification of Numerical
Procedures for the Analysis of Soil Liquefaction Problems, K. Arulanandan
and R. Scott (eds.), Vol. 1, pp. 799-808.*

*Adalier, K. and Elgamal, A.-W., (1996), "Site Remediation and
Seismic Response Mechanism," Proc., 3rd Int'l Workshop on Seismic Retrofit
of Bridges, Japan, December.*

*Adalier, K., Dobry, R., and Mahmud, M., (1996), "Centrifuge Model
Tests for Mine Tailing Slopes," Technical Report to Czech Technical
University and Energie Klaodno (Czech Republic), 36p.*

*Adalier, K., Elgamal, A.-W., and Martin, G.R., (1996), "Liquefaction
in Embankment Foundation Soils," Proc., 6th Japan-U.S. Workshop on
Earthquake Resistant Design of Lifeline Facilities and Countermeasures Against
Soil Liquefaction, Tokyo, Japan.*

*Adalier, K., Elgamal, A.-W., and Dobry, R., (1997), "VELACS-Extension
Project RPI Centrifuge Tests," Technical Report to National Science
Foundation, 55p.*

*Adalier, K., Zeghal, M., and Elgamal, A.-W., (1997), "Liquefaction
Mechanisms and Countermeasures," Proc., XIV Int'l Conf. on Soil Mechanics
and Foundation Engineering, Hamburg, Germany, September.*

*Arulanandan, K., Dobry, R., Elgamal, A.-W., Ko, H.-Y., Kutter, B.L.,
Prevost, J., Riemer, M.F., Schofield, A.N., Scott, R.F., Seed, R.B., Whitman,
R.V., and Zeng, X., (1994), "Interlaboratory Studies to Evaluate the
Repeatability of Dynamic Centrifuge Model Tests," Dynamic Geotechnical
Testing II, R.J. Ebelhar, V.P. Drnevich and B.L. Kutter (eds.), ASTM STP
1213, pp. 400-422.*

*Carnevale, R.A., (1994), "Dynamic Centrifuge Study of Reconsolidated
Saturated Sand," M.S. Thesis, Dept. of Civil Engineering, RPI, Troy,
NY.*

*Carnevale, R.A. and Elgamal, A.-W., (1993a), "Experimental Results
of RPI Centrifuge Model No. 4b," Proc., Int'l Conf. on the Verification
of Numerical Procedures for the Analysis of Soil Liquefaction Problems,
K. Arulanandan and R. Scott (eds.), Vol. 1, pp. 691-700.*

*Carnevale, R.A. and Elgamal, A.-W., (1993b), "Experimental Results
of RPI Centrifuge Model No. 12," Proc., Int'l Conf. on the Verification
of Numerical Procedures for the Analysis of Soil Liquefaction Problems,
K. Arulanandan and R. Scott (eds.), Vol. 1, pp. 1019-1026.*

*De, A., (1996), "Study of Interface Friction of Landfill Geosynthetics;
Static and Dynamic," Ph.D. Thesis, Dept. of Civil Engineering, RPI,
Troy, NY.*

*De, A. and Mahmud, M.B., (1992), "Study of Contaminant Migration
Through Soil in Geotechnical Centrifuge," Proc., Hazardous Waste Conf.,
University of Notre Dame, September.*

*De, A. and Zimmie, T.F., (1996), "Centrifuge Modeling to Study
Stability of Dams," Proc., 13th Annual Conf., Assoc. of State Dam Safety
Officials, Seattle, WA, pp. 630-639.*

*De, A. and Zimmie, T.F., (1997), "Factors Influencing Dynamic
Frictional Behavior of Geosynthetic Interfaces", Proc., Geosynthetics
`97, Long Beach, CA., Vol. 2, pp. 837-849.*

*Dobry, R. and Liu, L., (1992), "Centrifuge Modeling of Soil Liquefaction,"
Proc., 10th World Conf. on Earthquake Engineering, Madrid, Spain, Vol. 11,
pp. 6801-6809.*

*Dobry, R. and Taboada, V., (1994), "Possible Lessons from VELACS
Model No. 2 Results," Proc., Int'l Conf. on the Verification of Numerical
Procedures for the Analysis of Soil Liquefaction Problems, K. Arulanandan
and R.F. Scott (eds.), Vol. 2, pp. 1341-1352.*

*Dobry, R. and Taboada, V.M., (1996), "Investigation of Liquefaction
and Lateral Spreading by Centrifuge Model Tests," Proc., 4th Caltrans
Seismic Research Workshop, Sacramento, CA., July, 10p.*

*Dobry, R., Taboada, V., and Liu, L., (1995), "Centrifuge Modeling
of Liquefaction Effects During Earthquakes," Keynote Lecture, Proc.,
1st Int'l Conf. on Earthquake Geotechnical Engineering, Tokyo, Japan, Nov.
14-16, Reprint Vol., pp. 129-162.*

*Dobry, R., Abdoun, T. and O'Rourke, T.D., (1996), "Evaluation
of Pile Response Due to Liquefaction-Induced Lateral Spreading of the Ground,"
Proc., 4th Caltrans Seismic Research Workshop, Sacramento CA, July, 10p.*

*Dobry, R., Gutierrez, M. and Zeghal, M., (1996), "Centrifuge
Modeling of Surface Structure on Normally Consolidated Silty Sand Deposited
in Layers Under Water and Subjected to Seismic Excitation," Report
to INTEVEP S.A., Los Teques, Venezuela.*

*Elgamal, A.-W. and Adalier, K., (1996), "Soil Stabilization By
Ambient Pore Pressure and Geomembrane Containment," Geosynthetics Int'l,
Journal of the Int'l Geosynthetics Society, Vol. 3, No. 4, pp. 463-491.*

*Elgamal, A.-W. and Dobry, R., (1991), "Dynamic and Cyclic Centrifuge
Model Testing," Geotechnical News 9 (3):31-33, September.*

*Elgamal, A.-W., Dobry, R., Van Laak, P. and Nicolas-Font, J., (1991),
"Design, Construction and Operation of 100 g-ton Centrifuge at RPI,"
Centrifuge '91, H.-Y. Ko and F. G. McLean (eds.), pp. 27-34.*

*Elgamal, A.-W., Zeghal, M., Taboada, V.M., and Dobry, R., (1996),
"Analysis of Site Liquefaction and Lateral Spreading Using Centrifuge
Testing Records," Soils and Foundations, Vol. 36, No. 2, pp. 111-121,
June.*

*Gadre, A., (In Prep.), "Centrifuge Modeling of Lateral Loading
of Bridge Foundation Systems in Dry Sand," Ph.D. Thesis, Dept. of Civil
Engineering RPI, Troy, NY.*

*Gunturi, V.R., (1996), "Identification and Modeling of Seismic
Response of Landfills," Ph.D. Thesis, Dept. of Civil Engineering, RPI,
Troy, NY.*

*Gutierrez, M., (In Prep.), "Centrifuge Modeling of Seismic Response
and Liquefaction Failure of Small Earth Embankments on Loose Silty Sand,"
Ph.D. Thesis, Dept. of Civil Engineering, RPI, Troy, NY.*

*Gutierrez, A.M., Dobry, R., and Zeghal, M., (1994), "Centrifuge
Tests of Normally Consolidated Silty Sand Deposited in Layers Under Water
and Subjected to Seismic Excitation in a Laminar Box," Phase I Report
to INTEVEP, S.A., Los Teques, Venezuela and to the U.S. Army Corps of Engineers
Waterways Experiment Station, Vicksburg, MS, December.*

*Liu, L., (1992), "Centrifuge Earthquake Modeling of Liquefaction
and Its Effect on Shallow Foundations," Ph.D. Thesis, Dept. of Civil
Engineering, RPI, Troy, NY.*

*Liu, L. and Dobry, R., (1992), "Centrifuge Study of Shallow Foundation
on Saturated Sand During Earthquakes," Proc., 4th U.S.-Japan Workshop
on Earthquake Resistant Design of Lifeline Facilities and Countermeasures
for Soil Liquefaction, Honolulu, NCEER-92-0019, pp. 493-508.*

*Liu, L. and Dobry, R., (1994), "Seismic Settlements and Pore
Pressures of Shallow Foundations," Centrifuge '94, Leung, Lee and Tan
(eds.), pp. 227-232.*

*Liu, L. and Dobry, R., (1995), "Effect of Liquefaction on Lateral
Response of Piles by Centrifuge Model Tests," NCEER Bulletin, Vol.
9, No. 1, January, pp. 7-11.*

*Liu, L., and Dobry, R., (1997), "Seismic Response of Shallow
Foundations on Liquefiable Saturated Sand," Journal of Geotechnical
and Geoenvironmental Engineering, ASCE, Vol. 123, No. 6, June.*

*Mahmud, M.B., (1993), "Geotechnical Centrifuge Modeling of Contaminant
and Radioactive Waste Migration in Soil," M.S. Thesis, Dept. of Civil
Engineering, RPI, Troy, NY.*

*Mahmud, M.B., (In Prep.), "Centrifuge Modeling of an Innovative,
Rapidly Installed and Economical MSES for Mechanically Stabilized Slopes,"
Ph.D. Thesis, Dept. of Civil Engineering, RPI, Troy, NY.*

*Mahmud, M.B. and Zimmie, T.F., (1996), "Instrumentation for Centrifuge
Modeling of Geotextile Reinforced Slopes," Earth Reinforcement, H.O.
Chiai, N. Yasufuku and K. Omine (eds.), pp. 847-852.*

*Mahmud, M.B. and Zimmie, T.F., (1997), "The Influence of Surcharge
Loading on the Stability of Directly Installed MSES," Proc., Int'l
Symposium on Mechanically Stabilized Backfill (MSB), Denver, CO.*

*Parra, E., (1996), "Numerical Modeling of Liquefaction and Lateral
Ground Deformation Including Cyclic Mobility and Dilation Response in Soil
Systems," Ph.D. Thesis, Dept. of Civil Engineering, RPI, Troy, NY.*

*Parra, E., Adalier, K., Elgamal, A.-W., Ragheb, A. and Zeghal, M.,
(1996), "Analysis of Site Liquefaction and Remediation," Proc.,
11th World Conf. on Earthquake Engineering, Acapulco, Mexico, 8p.*

*Ragheb, A., (1991), "Effect of Gradual Reinforcement Compromise
on the Behavior of Mechanically Stabilized Earth Walls," M.S. Thesis,
Dept. of Civil Engineering, RPI, Troy, NY.*

*Ragheb, A.M., (1994), "Numerical Analysis of Seismically Induced
Deformations in Saturated Granular Soil Strata," Ph.D. Thesis, Dept.
of Civil Engineering, RPI, Troy, NY.*

*Ragheb, A. and Elgamal, A.-W., (1991), "Effect of Gradual Reinforcement
Compromise on the Behavior of Mechanically Stabilized Earth Walls,"
Centrifuge '91, H.-Y. Ko and F.G. McLean (eds.), pp. 333-340.*

*Sharp, M., (In Prep.), "Development of Field Charts to Predict
Liquefaction-Induced Lateral Spreading from Cone Penetration Tests Modeled
in the Centrifuge," Ph.D. Thesis, Dept. of Civil Engineering, RPI,
Troy, NY.*

*Taboada, V.M., (1995), "Centrifuge Modeling of Earthquake-Induced
Lateral Spreading in Sand Using a Laminar Box," Ph.D. Thesis, Dept.
of Civil Engineering, RPI, Troy, NY.*

*Taboada, V.M. and Dobry, R., (1993a), "Experimental Results of
Model No. 1 at RPI," Proc., Int'l Conf. on the Verification of Numerical
Procedures for the Analysis of Soil Liquefaction Problems, K. Arulanandan
and R.F. Scott (eds.), Vol. 1, pp. 3-17.*

*Taboada, V.M. and Dobry, R., (1993b), "Experimental Results of
Model No. 2 at RPI," Proc., Int'l Conf. on the Verification of Numerical
Procedures for the Analysis of Soil Liquefaction Problems, K. Arulanandan
and R.F. Scott (eds.), Vol. 1, pp. 277-294.*

*Taboada, V.M. and Dobry, R., (1993c), "Experimental Results of
Attempted Duplication of Model No. 3 at RPI," Proc., Int'l Conf. on
the Verification of Numerical Procedures for the Analysis of Soil Liquefaction
Problems, K. Arulanandan and R.F. Scott (eds.), Vol. 1, pp. 471-482.*

*Taboada, V.M. and Dobry, R., (1993d), "Experimental Results of
Model No. 4a at RPI," Proc., Int'l Conf. on the Verification of Numerical
Procedures for the Analysis of Soil Liquefaction Problems, K. Arulanandan
and R.F. Scott (eds.), Vol. 1, pp. 611-621.*

*Taboada, V.M., Abdoun, T. and Dobry, R., (1996), "Prediction
of Liquefaction-Induced Lateral Spreading by Dilatant Sliding Block Model
Calibrated by Centrifuge Tests," Proc., 11th World Conf. on Earthquake
Engineering, Acapulco, Mexico, Paper No. 376, 8p.*

*Ting, N.-H. and Whitman, R.V., (1993), "Dynamic Centrifuge Testing
of a Tilting Retaining Wall with Saturated Backfill," Research Report
R93-13, Dept. of Civil and Environmental Engineering, Massachusetts Institute
of Technology, Cambridge, MA.*

*Ting, N.-H. and Whitman, R.V., (1994), "Modeling of Tilting Retaining
Wall with Saturated Backfill," Centrifuge '94, Leung, Lee and Tan (eds.),
pp. 209-214.*

*Tufenkjian, M.R. and Vucetic, M., (1992), "Seismic Stability
of Soil Nailed Excavations," Proc., Symposium on the Theory of Earth
Reinforcement and Practice, Kyushu, Japan.*

*Tufenkjian, M.R., Vucetic, M. and Doroudian, M., (1991), "Stability
of Soil Nailed Excavations," Proc., Int'l Workshop on Technology for
Hong Kong's Infrastructure Development, pp. 751-762.*

*Van Laak, P., (1996), "Development of Dynamic Capability for
Geotechnical Centrifuge Model Studies," Ph.D. Thesis, Dept. of Civil
Engineering, RPI, Troy, NY.*

*Van Laak, P., Elgamal, A.-W., and Dobry, R., (1994a), "Design
and Performance of an Electrohydraulic Shaker for the RPI Centrifuge,"
Centrifuge '94, Leung, Lee and Tan (eds.), pp. 139-144.*

*Van Laak, P., Taboada, V., Dobry, R., and Elgamal, A.-W., (1994b),
"Earthquake Centrifuge Modeling Using a Laminar Box," Dynamic
Geotechnical Testing II, R.J. Ebelhar, V.P. Drnevich and B.L. Kutter (eds.),
ASTM STP 1213, pp. 370-384.*

*Zeghal, M. and Elgamal, A.-W., (1994), "Analysis of Site Liquefaction
Using Earthquake Records," Journal of Geotechnical Engineering, ASCE,
Vol. 120, No. 6, pp. 996-1017.*

*Zimmie, T.F., (1995), "Geo-environmental Research Using Centrifuges,"
The Encyclopedia of Environmental Control Technology, P.N. Cheremisinoff
(ed.), Houston, TX, Vol. 9, Ch. 10, pp. 335-366.*

*Zimmie, T.F. and De, A., (1995), "Geosynthetic Research Using
the Centrifuge," Geotechnical News, Vol. 13, No. 3, pp. 30-33.*

*Zimmie, T.F. and Mahmud, M.B., (1996), "Centrifuge Modeling of
a Rapidly Installed MSES," Env. Geotechnology, Vol. 1, pp. 795-804.*

*Zimmie, T.F., Mahmud, M.B. and De, A., (1993), "Application of
Centrifuge Modeling to Contaminant Migration in Seabed Waste Disposal,"
Proc., 4th Canadian Conf. on Marine Geotechnical Engineering, St. John's,
Newfoundland, June 1993, Vol. II, pp. 610-624.*

*Zimmie, T.F., De, A. and Mahmud, M.B., (1994a), "Accelerated
Groundwater Transport Studies Using a Geotechnical Centrifuge," Transportation
Research Record, No. 1434, Washington, D.C., pp. 47-54.*

*Zimmie, T.F., De, A. and Mahmud, M.B., (1994b), "Simulation of
Long Term Performance of Landfill Covers," Centrifuge `94, Leung, Lee
and Tan (eds.), pp. 375-380.*

*Zimmie, T.F., De, A. and Mahmud, M.B., (1994c), "Use of a Geotechnical
Centrifuge to Simulate Long Term Landfill Cover Performance," Proc.,
8th Int'l Conf. on Computer Methods and Advances in Geomechanics, Morgantown,
WV, pp. 1809-1814.*

*Zimmie, T.F., De, A., and Mahmud, M.B., (1994d), "Centrifuge
Modeling to Study Dynamic Friction at Geosynthetic Interfaces," Proc.,
5th Int'l Conf. on Geotextiles, Geomembranes, and Related Products, Vol.
1, pp. 415-418.*

*Zimmie, T.F., Mahmud, M.B. and De, A., (1994e), "Accelerated
Physical Modeling of Radioactive Waste Migration in Soil," Canadian
Geotechnical Journal, October 1994, Vol. 31, No. 5, pp. 683-691.*

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