Pitt | Swanson Engineering
Vallejo, Luis E
Civil & Environmental Engr
Vallejo, Luis E
Faculty
Professor
Office: Benedum 726
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PhD in Civil Engineering, University of Wisconsin, 1977

MS in Civil Engineering, Michigan State University, 1974

BS in Civil Engineering, Washington State University, 1972

Application of Fracture Mechanics and Fractal theories to geotechnical engineering

cracking of soils

interface shear strength between soils and geomembranes

mechanical properties of cellular concrete

mechanics of crushing of granular materials

mechanics of sand liquefaction

mechanics of slaking of shales

mobilization mechanics of mudflows and debris flows

shear strength of soils

Stability and evolution mechanics of natural slopes

subsidence due to long wall mining

(2010) Honorable Mention to Paper presented and published in the ASCE's Proceedings of Geoflorida 2010, West Palm Beach, Florida, February 2010..

(2008) Member of the Editorial Board of the international journal: Geomechanics and Engineering, October 2008 to date.

(2006) Best Paper Award on the subject of Numerical Analysis, Geocongress 2006: Geotechnical Engineering in the Information Technology Age, Atlanta, Georgia, February 26, 2006..

(2004) Associate Editor of the ASCE's Journal of Geotechnical and Geo-environmental Engineering, Nov. 1, 2004 to date.

(2001) Member of the Editorial Board of the International Journal Engineering Geology, 2001 to date..

(2000) Morada al Sur Award from the State of Nariño, Colombia for Contributions to Education and Technology; September 2000.

(1991) Award for Superior Performance, Office of Surface Mining, U.S. Dept. of the Interior, Pittsburgh, 1991.

(1988) Honorable Mention for Research, Sigma Xi, 1988..

(1986) Lilly Endowment Teaching Fellowship for Excellence in Teaching, May 1986 to April 1987.

(1970) Tuition Scholarship, Washington State University (1970-1972) and Michigan State University (1973-1974)..

Vallejo, L.E., Lobo-Guerrero, S., Seminsky, L.F., and Caicedo, B., In press, "The reinforcement of soils by dispersed oversized particles," Proceedings of the 18th Int. Conf. on Soil Mechanics and Foundation Eng.

Vallejo, L.E., 2012, "Analysis of the failure of a rock slope in Tulum, Mexico," Revista Internacional de Desastres Naturales, vol.12, no.1, pp. 97-101.

Vallejo, L.E., 2012, "Fractal evaluation of the level of alligator cracking in pavements," Geomechanics and Engineering, vol.4, no.3, pp. 219-227.

Vallejo, L.E., 2012, "The influence of notches on the stability of soil and rock slopes," Proceedings of the 11th Int. Symposium on Landslides and Engineered Slopes, Vol. 1, pp. 415-419, Banff, Canada.

Vallejo, L.E., and Abu-Ali, S., 2012, "The influence of crack roughness on the compression and shear strengths of brittle fissured materials."

Vallejo, L.E., and Liu, Z., 2012, "The angle of repose of granular systems measured using hollow cylinders," Proceedings of the 11th Int. Symposium on Landslides and Engineered Slopes, Vol. 1, pp. 937-942, Banff, Canada.

Vallejo, L.E., and Lobo-Guerrero, S., 2012, "The shear strength of granular materials containing dispersed oversized particles," Int. J. of Geotechnical Eng., vol.6, no.3, pp. 371-379.

Caicedo, B., Ocampo, M., Vallejo, L.E., and Monroy, J., 2012, "Hollow cylinder apparatus for testing unbound granular materials of pavements," Int. J. of Road Materials and Pavement Design, vol.13, no.3, pp. 455-479.

Kutschke, W.G., and Vallejo, L.E., 2012, "A finite element analysis of the propagation of a toe crack in a vertical slope," Proceedings of the 11th Int. Symposium on Landslides and Engineered Slopes, Vol. 2, pp. 1807-1812, Banff, Canada.

Kutschke, W.G., and Vallejo, L.E., 2012, "Investigation of lateral stress relief using finite elements and fracture mechanics.: a case history study of the Saxon Pit.," J. of Geotechnical and Geo-environmental Eng. (ASCE), vol.138, no.10, pp. 1277-1283.

Vallejo, L.E., 2011, "Compressive strength of unsaturated fissured clays," Unsaturated Soils, E. Alonso, and A. Gens, eds., Taylor and Francis, Vol. 1, pp. 387-390, London.

Vallejo, L.E., 2011, "Fractal assessment of the level of alligator cracking in pavements," Transportation Research Board, Annual Meeting 2011, Washington, D.C..

Vallejo, L.E., 2011, "Fracture criteria for fissured clays under mixed-mode loading."

Vallejo, L.E., 2011, "Mechanics of the slaking of shales," Geomechanics and Engineering: An International Journal, vol.3, no.3, pp. 219-231.

Vallejo, L.E., 2011, "Shale pore geometry and the performance of granular bases and rock fills under drying and wetting conditions," Transportation Research Board, Annual Meeting 2011, Washington, D.C..

Vallejo, L.E., and Au, M.C., 2011, "Shaking table tests on dry and saturated sand with large embedded objects."

Vallejo, L.E., and Stweart-Murphy, A., 2011, "Pore geometry induced suction and the slaking of shales," Unsaturated Soils, E. Alonso, and A. Gens, eds., Taylor and Francis, Vol. 2, pp. 1477-1482, London.

Vallejo, L.E., Chik, Z., Lobo-guerrero, S., and Caicedo, B., 2011, "Force chains and the fragmentation of granular materials," Proceedings of the 14th Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Toronto, Canada.

Vallejo, L.E., Lalley, K., Long, M., and Chaparro, L.F., 2011, "Geotechnical engineering in the Americas before Columbus," Proceedings of the 14th Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Toronto, Canada.

Caicedo, B., Vallejo, L.E., and Martinez, A., 2011, "Analysis of the abrasion and crushing of unsaturated sands using acoustic emissions," International Symposium on Deformation Characteristics of Geomaterials, Seoul, Korea.

Caicedo, B., Cacique, A., Contreras, C., and Vallejo, L.E., 2011, "Experimental study of the strength and crushing of unsaturated spherical particles," Proceedings of the 14th Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Toronto, Canada.

Caicedo, B., Martinez, A., and Vallejo, L.E., 2011, "Assessing of crushing of granular materials using acoustic emissions," Proceedings of the 14th Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Toronto, Canada.

Kutschke, W., and Vallejo, L.E., 2011, "Stability and impacts of unsupported vertical cuts in a stiff clay."

Vallejo, L.E., and Chik, Z., 2010, "Measurement of the abrasion of granular materials using fractals."

Vallejo, L.E., and Pappas, D., 2010, "Effect of nondurable material on settlement of embankments," Transportation Research Record: Journal of the Transportation Research Board, no.2170, pp. 84-89.

Guitierrez, J.J., Vallejo, L.E., Lin, J.S., and Painter, R., 2010, "Impact of long wall mining of coal on highways in southern Pennsylvania," Land Subsidence Associated Hazards and the Role of Natural Resources Development, 8th International Symposium on Land Subsidence, D. Carreon-Freyre, M. Cerca, and D.I. Galloway, eds., pp. 120-125, Querétaro, Mexico.

Gutierrez, J.J., Vallejo, L.E., Lin, J.S., and Painter, R., 2010, "Impact of long wall mining on highways," Proceedings of the 44th US Rock Mechanics Symposium, Salt Lake City, Utah.

Kutschke, W., and Vallejo, L.E., 2010, "Failure analysis of an instrumented stiff clay slope."

Lobo-Guerrero, S., 2010, "Crushing of particles under simulated static and centrifuge forces."

Lobo-Guerrero, S., and Vallejo, L.E., 2010, "DEM analysis of the effect of particle crushing on the bearing capacity of footings," International Journal of Geotechnical Engineering, vol.4, pp. 351-359.

Lobo-Guerrero, S., and Vallejo, L.E., 2010, "Fibre-reinforcement of granular materials: DEM visualization .and analysis," Geomechanics and Geoengineering, vol.5, no.2, pp. 79-89.

Lobo-Guerrero, S., and Vallejo, L.E., 2010, "The effectiveness of geosynthetic reinforcement, tamping, and stone blowing of rail track ballast beds under dynamic loading: DEM analysis," Geomechanics and Engineering: An International Journal, vol.2, no.3, pp. 161-176.

Vesga, L.F., and Vallejo, L.E., 2010, "Analysis of particle shape using fractals."

Vallejo, L.E., 2009, "Fractal Analysis of Temperature-Induced Cracking in Clays and Rocks," Geotechnique, vol.59, no.3, pp. 283-286.

Vallejo, L.E., and Chik, Z., 2009, "Fractal and Laboratory Analyses of the Crushing and Abrasion of Granular Materials," Geomechanics and Engineering: An International Journal, vol.1, no.4, pp. 323-335.

Vallejo, L.E., and Lobo-Guerrero, S., 2009, "Fractal Fragmentation of Granular Materials Under Compression," Powders and Grains 2009: Proceedings of the 6th International Conference on Micromechanics of Granular Media, pp. 847-850, Golden, Colorado.

2009, "The Influence of Isolated Fissures on the Hydraulic Conductivity of Clays," Poro-Mechanics IV, Proceedings Fourth Biot Conference on Poromechanics, pp. 977-982, Columbia University, New York.

Gutierrez, J.J., Vallejo, L.E., and Garcia, C.I., 2009, "The Hydraulic Conductivity of Sands with Dispersed Oversized Particles," Proceedings 17th International Conference on Soil Mechanices and Geotechnical Engineering, Vol. 1, pp. 163-165, Cairo, Egypt.

Lobo-Guerrero, S., and Vallejo, L.E., 2009, "Implementing Particle Fragmentation on DEM: Geotechnical Applications," ," Proceedings of the 4th International Workshop on New Frontiers in Computational Geotechnics, pp. 69-74, Pittsburgh, PA.

Vallejo, L.E., 2008, "The formation and effect of wave induced notches on the failure of coastal slopes," Proceedings of the ASCE's Conference: Solutions for Coastal Disasters 2008, L. Ewing, B. Jaffe, C. Jones, and L. Wallendorf, eds., pp. 584-595, Hawaii.

Vallejo, L.E., and Zhou, Y., 2008, "Effect of the compatibility between geomembrane and granular materials on the interface friction angle," Proceedings of the International Conference: Geoamericas 2008, R.J. Bathurst, and E.M. Palmeira, eds., Cancun, Mexico.

Jaime, M.C., Johnson, M.G., Hale, P., Grzejka, T., Vallejo, L.E., and Lin, J.S., 2008, "A Rational Procedure for Rock Slope Design," Proceedings of the 2nd Annual Pennsylvania Transportation Research Forum, M. Bilec, and K.H. Harries, eds..

Vesga, L.F., Vallejo, L.E., and Lobo-Guerrero, S., 2008, "DEM analysis of the crack propagation in brittle clays under uniaxial compression tests," International Journal for Numerical and Analytical Methods in Geomechanics, vol.32, no.11, pp. 1405-1415.

Lobo-Guerrero, S., and Vallejo, L.E., 2007, "Influence of pile shape and pile interaction on the crushable behavior of granular materials around driven piles: DEM analyses," Granular Matter, vol.9, no.3-4, pp. 241-250.

Vallejo, L.E., Lobo-Guerrero, S., and Hammer, K., 2006, "Degradation of a granular base under a flexible pavement: DEM Simulation," International Journal of Geomechanics, vol.6, no.6, pp. 435-439.

Lobo-Guerrero, S., 2006, "DEM as an educational tool in geotechnical engineering.," Proceedings Geocongress 2006, 6 pages, Atlanta.

Lobo-Guerrero, S., and Vallejo, L.E., 2006, "Application of Weibull statistics to the tensile strength of rock aggregates," Journal of Geotechnical and Geoenvironmental Engineering, vol.32, no.6, pp. 786-790.

Lobo-Guerrero, S., and Vallejo, L.E., 2006, "Discrete Element Method analysis of rail track ballast degradation during cyclic loading," Granular Matter -An International Journal, vol.8, no.3-4, pp. 195-204.

Lobo-Guerrero, S., and Vallejo, L.E., 2006, "Influence of pile shape on the crushable behavior of granular materials around driven piles: DEM analysis," Proceedings Geocongress 2006, 6 pages, Atlanta.

Lobo-Guerrero, S., and Vallejo, L.E., 2006, "Modeling granular crushing in ring shear tests: experimental and numerical analyses," Soils and Foundations, vol.46, no.2, pp. 39-49.

Lobo-Guerrero, S., and Vallejo, L.E., 2006, "The degradation of a simulated ballast bed and the effectiveness of track maintenance techniques," Proceedings of the 41st Rock Mechanics Symposium, 12 pages, Golden, Colorado.

Lobo-Guerrero, S., and Vallejo, L.E., 2006, "Visualization of crushing evolution in granular materials under compression using DEM," International Journal of Geomechanics, vol.6, no.3, pp. 195-200.

Vesga, L.F., and Vallejo, L.E., 2006, "Direct and indirect tensile tests for measuring the equivalent effective stress in a kaolinite clay," Unsaturated Soils, ASCE's Geotechnical Special Publication No. 147, D.G. Fredlund, S. Houston, G.A. Miller, and C.E. Zapata, eds., pp. 1290-1301.

Vallejo, L.E., and Chik, Z., 2005, "The evolution of crushing in granular materials and its effect on their mechanical properties," Proceedings of XVI International Conference on Soil Mechanics and Foundation Engineering, Vol. 3, pp. 1793-1796, Osaka, Japan.

Vallejo, L.E., and Lobo-Guerrero, S., 2005, "Evaluation of porosity changes in a granular material undergoing particle crushing using DEM," Proceedings of the 3rd Biot Conference on Poromechanics, Balkema Press, pp. 573-578.

Vallejo, L.E., and Lobo-Guerroero, S., 2005, "The elastic moduli of clays with dispersed oversized particles," Engineering Geology, vol.78, pp. 163-171.

Vallejo, L.E., Lobo-Guerrero, S., and Chik, Z., 2005, "A Network of Fractal Force Chains and their Effect in Granular Material Under Compression, Chapter 5," in Fractals in Engineering: New Trends in Theory and Applications, E. Lutton, and J.L. Vehel, eds., Springer, pp. 67-80, London.

Chik, Z., and Vallejo, L.E., 2005, "Characterization of the angle of repose of binary granular materials.," Canadian Geotechnical Journal, vol.42, no.2, pp. 683-692.

Lobo-Guerrero, L.E., and Vallejo, L.E., 2005, "DEM evaluation of the crushing of a granular gouge in fault zones," Proceedings of the 40th U.S. Symposium on Rock Mechanics, Anchorage, Alaska.

Lobo-Guerrero, S., and Vallejo, L.E., 2005, "Analysis of crushing of granular materials under isotropic and biaxial stress conditions," Soils and Foundations, vol.45, no.4, pp. 79-88.

Lobo-Guerrero, S., and Vallejo, L.E., 2005, "Crushing a weak granular material: Experimental-numerical analysis," Geotechnique, vol.55, no.3, pp. 245-249.

Lobo-Guerrero, S., and Vallejo, L.E., 2005, "DEM analysis of crushing around driven piles in granular materials," Geotechnique, vol.55, no.8, pp. 617-623.

Lobo-Guerrero, S., and Vallejo, L.E., 2005, "DEM simulation of crushing of granular materials under direct shear stress conditions," Journal of Geotechnical and Geoenvironmental Engineering, vol.131, no.10, pp. 1295-1300.

Vesga, L., and Vallejo, L.E., 2005, "Strength of an unsaturated kaolinite clay under suction pressures," Proceedings of the XVI International Conference on Soil Mechanics and Foundation Engineering, Vol. 2, pp. 611-614, Osaka, Japan.

Vallejo, L.E., 2004, "Shear strength parameters and surface instabilities associated with mudflows," Proceedings of the International Workshop on: Occurrence and Mechanisms of Flows in Natural Slopes and Earthfills (Flows2003), L. Picarelli, ed., Patron Editore, pp. 265-270, Bologna, Italy.

Vallejo, L.E., Chik, Z., Tucek, S., and Caicedo, B., 2004, "Fractal analysis of the abrasion and crushing of gravels," Proceedings of the 6th Int. Conf. on Pavements Unbound, A.R. Dawson, ed., A.A. Balkema Publishers, pp. 43-50, Nottingham, England.

Vallejo, L.E., Sass, R., Craig, R., and Lobo-Guerrero, S., 2004, "The shear strength and stability of a soil mass containing dispersed oversize particles," Proceedings of the VI International Symposium on Landslides, A.A. Balkema Publishers, Vol. 1, pp.697-700, Rio de Janeiro, Brazil.

Lobo-Guerrero, S., and Vallejo, L.E., 2004, "Modeling of material crushing in granular road bases," Proceedings of the 6th Int. Conf. on Pavements Unbound, A.R. Dawson, ed., A.A. Balkema Publishers, pp. 33-41, Nottingham, England.

Vallejo, L.E., 2003, "Crushing of granular bases: fractal and laboratory analyses," Keynote Lecture, XIV Colombian Symposium on Pavements Engineering, and First Ibero-american Symposium on Pavement Engineering, Department of Civil Engineering, 18 pages, Universidad del Cauca, Department of Civil Engineering, Universidad del Cauca, Popayán, Colombia.

Vallejo, L.E., and Lobo-guerrero, S., 2003, "The elastic moduli of dry and unsaturated clay-sand mixtures," Proceedings of the XII Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Vol 1, 853-858, MIT, Boston.

Vallejo, L.E., and Scovazzo, V., 2003, "Determination of shear strength parameters associated with mudflows," Soils and Foundations, vol.43, no.2, pp. 129-133.

Caicedo, B., Vallejo, L.E., Lizcano, A., and Jaime, C., 2003, "Self-weight consolidation in a centrifuge of a clay mass containing simulated large particles," Proceedings of the XII Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Vol. 1, 697-702, MIT, Boston.

Lobo-Guerrero, S., and Vallejo, L.E., 2003, "The elastic moduli of soils with dispersed oversize particles."

Vallejo, L.E., 2002, "Analysis of the failure of coastal slopes: a fracture mechanics approach," proceedings of the IX Colombian Geotechnical Engineering Congress, Medelin.

Vallejo, L.E., 2002, "Fractal analysis of the pore structure in the shear zone of granular materials," Proceedings of the 2nd Biot Conference on Poromechanics, pp. 587-591, Grenoble, France.

Vallejo, L.E., 2002, "Fractals in geotechnical engineering," Proceedings of the IX Colombian Geotechnical Engineering Congress, Medelin.

Vallejo, L.E., 2002, "Mechanics of crack propagation in brittle and plastic clays," Proceedings of the IX Colombian Geotechnical Engineering Congress, Medelin.

Vallejo, L.E., 2002, "Modes of failure of coastal slopes as a result of wave action," Proceedings of the ASCE's Conference on Solutions to Coastal Disasters'02, pp. 664-673, San Diego, California.

Vallejo, L.E., 2002, "The behavior of granular materials containing large particles: laboratory and finite element analysis," Proceedings of the 5th European Conference on Numerical Methods in Geotechnical Engineering, pp. 39-43, Paris.

Vallejo, L.E., and Lobo-guerrero, S., 2002, "The elastic moduli of soils with dispersed oversize particles," Proceedings of the 15th ASCE Engineering Mechanics Conference, the American Society of Civil Engineers (ASCE), 7 pages, Reston, VA, Columbia University, New York.

Vallejo, L.E., and Scovazzo, V., 2002, "Sand blows from compressive (P) waves," Proceedings of the International Conference on Physical Modeling in Geotechnics, pp. 525-529, St. John, Canada.

Chik, Z., and Vallejo, L.E., 2002, "The effects of foundation failures in contaminated grounds," Proceedings of the 2nd World Engineering Congress, pp. 258-263, Kuching, Malaysia.

Vallejo, L.E., 2001, "Analysis of the pore structure in the shear zones of granular materials," Proceedings of the XV International Conference on Soil Mechanics and Foundation Engineering, Vol. 1, pp. 629-631, Istanbul, Turkey.

Vallejo, L.E., 2001, "Fractal assessment of the surface texture of pavements," International Journal of Pavement Engineering, vol.2, no.2, pp. 149-156.

Vallejo, L.E., 2001, "Interpretation of the limits in shear strength in binary granular mixtures," Canadian Geotechnical Journal, vol.38, no.5, pp. 1097-1104.

Vallejo, L.E., and Stewart-Murphy, A., 2001, "Influence of pore wall roughness on slaking of shales," Proceedings of the 38thU.S. Rock Mechanics Symposium: Rock Mechanics in the National Interest, Vol. 1, pp. 93-98, Washington, D.C..

Vallejo, L.E., 2000, "Failure modes of coastal slopes forming part of the Great Lakes, Southern California, England and Mexican shorelines," Proceedings of the National Beach Preservation Conference, pp. 261-263, Hawaii.

Vallejo, L.E., and Mawby, R., 2000, "Porosity influence on the shear strength of granular material-clay mixtures," Engineering Geology, vol.58, pp. 125-136.

Iannacchione, A.T., and Vallejo, L.E., 2000, "Shear strength evaluation of clay-rock mixtures."

Vallejo, L.E., 1999, "Shear band propagation in clay slopes," Proceedings of the International Symposium on Slope Stability Engineering, J.C. Jiang, N. Yagi, and T. Yamagami, eds., A.A. Balkema Press, Vol. 1, pp. 287-292, Matsuyama, Japan.

Vallejo, L.E., and Mawby, R., 1999, "The shear strength of granular material-clay mixtures," Proceedings of the XI Panamerican Conference on Soil Mechanics and Foundation Engineering, Vol. 1, pp. 417-424, Iguazu, Brazil.

Vallejo, L.E., and Stewart-Murphy, A., 1999, "Fractal Pores and the Degradation of Shales, Chapter 15," in Fractals: Theory and Applications in Engineering, M. Dekking, J. Levy-Vehel, E. Lutton, and C. Tricot, eds., Springer, pp. 229-243, London.

Hu, W., Smith, A.E., Vallejo, L.E., Neufeld, R.D., and Golden, D.M., 1999, "Development of artificial neural networks-based autoclaved cellular concrete models.," Proceedings of the 13th International Symposium on Use and Management of Coal Combustion Products (CCPs), Vol. 1, pp. 31-1 to 31-21, Orlando, Florida.

Vallejo, L.E., 1997, "Discussion of: Modeling lateral sliding of slope due to liquefaction of sand layer," Journal of Geotechnical Engineering, ASCE, vol.123, no.1, pp. 80-82.

Vallejo, L.E., 1997, "Fractal analysis of crack evolution in drying clay," Proceedings of the 3rd International Conference on Fractals in Engineering, pp. 128-131, Arcachon, France.

Vallejo, L.E., 1997, "Fractals in engineering geology," Engineering Geology, vol.48, no.3-4, pp. 159-161.

Vallejo, L.E., 1997, "Surge wave development in debris flows," Soils and Foundations, vol.37, no.4, pp. 115-119.

Vallejo, L.E., and Shettima, M., 1997, "Creep crack propagation and the progressive failure of slopes.," Proceedings of the International Symposium on Deformation and Progressive Failure in Geomechanics, A. Asaoka, and F. Oka, eds., pp. 295-298, Nagoya, Japan.

Vallejo, L.E., and Shettima, M., 1997, "Fault Movement and its Impact on Ground Deformations and Engineering Structures, Chapter 4, No. 81," in Earthquake Proof Design and Active Faults, Y. Kanaori, ed., Elsevier Science, pp. 43-60, Amsterdam.

1997, "Fractals in Engineering Geology."

Hu, W., Neufeld, R.D., Vallejo, L.E., Kelly, C., and Latona, M.C., 1997, "Strength properties of autoclaved cellular concrete with high volume fly ash," Journal of Energy Engineering, ASCE, vol.123, no.2, pp. 44-54.

Huang, C.P., Chaparro, L.F., and Vallejo, L.E., 1997, "Fractal dimension of profiles and surfaces using fuzzy morphological coverings," Engineering Geology, vol.48, no.3-4, pp. 245-253.

Hyslip, J.P., and Vallejo, L.E., 1997, "Fractal analysis of the roughness and size distribution of granular materials," Engineering Geology, vol.48, no.3-4, pp. 231-244.

Latona, M.C., Neufeld, R.D., Vallejo, L.E., Hu, W., and Kelly, C., 1997, "Leachate formation and random exhalation from fly ash autoclaved cellular concrete," Journal of Energy Engineering, ASCE, vol.123, no.2, pp. 55-67.

Latona, M.C., Neufeld, R.D., Hu, W., and Vallejo, L.E., 1997, "Response of Microtox organisms to leachates of autoclaved cellular concrete," Journal of Energy Engineering, ASCE, vol.123, no.2, pp. 35-43.

Nettleship, I., Cisko, L., and Vallejo, L.E., 1997, "Aggregation of clay in the hydrometer," Canadian Geotechnical Journal, vol.34, pp. 621-626.

Pappas, D.M., and Vallejo, L.E., 1997, "The settlement and degradation of non- durable shales associated with coal mine embankments," International Journal of Rock Mechanics and Mining Sciences, vol.34, no.3-4, pp. 779-789.

Vallejo, L.E., 1996, "Evaluating the variability of engineering properties of soil deposits using fractals."

Vallejo, L.E., 1996, "Fractal analysis of the fabric changes in a consolidating clay," Engineering Geology, vol.43, no.4, pp. 281-290.

Vallejo, L.E., and Liang, R., 1996, "Engineered Contaminated Soils and Interaction of Soil Geomembranes."

Vallejo, L.E., and Shettima, M., 1996, "Fault movement and its impact on ground deformations and engineering structures," Engineering Geology, vol.43, no.2/3, pp. 113-129.

Vallejo, L.E., and Zhou, Y., 1996, "Interaction between geomembranes and granular materials."

Boward, J.F., and Vallejo, L.E., 1996, "Clay liner crack propagation."

Latona, M.C., Neufeld, R.D., Vallejo, L.E., Hu, W., and Kelly, C., 1996, "Environmental impacts of autoclaved cellular concrete."

Neufeld, R.D., Vallejo, L.E., Hu, W., Latona, M.W., Kelly, C., and Brandon, D., 1996, "Environmental and Physical properties of autoclaved cellular concrete."

Neufeld, R.D., Vallejo, L.E., Kelly, C., and Hu, W., 1996, "The autoclaved cellular concrete production process: Important variables and their influence in manufacturing."

Zhou, Y., Vallejo, L.E., and Hsu, D.C., 1996, "Analysis and design of liner systems for a large ash residual landfill."

Vallejo, L.E., 1995, "Fractal analysis of granular materials," Geotechnique, vol.45, no.1, pp. 159-164.

Vallejo, L.E., Al-Saleh, S., and Shettima, M., 1995, "Evaluation of fracture creteria for fissured clays," Proceedings of the X Panamerican Conference on Soil Mechanics and Foundation Engineering, Vol. 1, pp. 559-570, Guadalajara, Mexico.

Vallejo, L.E., and Yoo, H.K., 1995, "Reinforcement of fissured clays by short steel fibers," Transportation Research Record, Journal of the Transportation Research Board, no.1474, pp. 108-115.

Vallejo, L.E., and Zhou, Y., 1995, "Fractal approach to measuring the roughness of geomembranes," Journal of Geotechnical Engineering, ASCE, vol.121, no.5, pp. 442-447.

Vallejo, L.E., and Zhou, Y., 1995, "Fractal dimension of granular materials and their engineering properties," Proceedings of the 10th Engineering Mechanics Conference, Sponsored by the American Society of Civil Engineers, S. Sture, ed., Vol. 1, pp. 469-472, Boulder, Colorado.

Vallejo, L.E., and Zhou, Y., 1995, "The relationship between the fractal dimension and Krumbein's roundness number," Soils and Foundations, vol.35, no.1, pp. 163-167.

Bazan-Arias, C., and Vallejo, L.E., 1995, "Granular binary mixtures under direct shear," Proceedings of the X Panamerican Conference on Soil Mechanics and Foundation Engineering, Vol. 1, pp. 547-558, Guadalajara, Mexico.

Holchin, J.D., and Vallejo, L.E., 1995, "The liquefaction of sand lenses due to cyclic loading," Proceedings of the 3rd International Conference on Geotechnical Earthquake Engineering and Soil Dynamics, Vol. 1, pp. 253-259, St. Louis.

Iannacchione, A.T., and Vallejo, L.E., 1995, "Factors affecting the slope stability of Kentucky's abandoned mine lands.," Proceedings of the 35th U.S. Symposium on Rock Mechanics, J.K. Daemen, and R.A. Schultz, eds., pp. 837-842, Reno, Nevada.

Stump, D.E., Vallejo, L.E., and Bazan-Arias, N.C., 1995, "Analysis of the creeping behavior of a natural slope in Kentucky."

Vallejo, L.E., 1994, "Application of Fracture Mechanics to Soils: An Overview."

Vallejo, L.E., 1994, "Fractal analysis of the slake durability test," Canadian Geotechnical Journal, vol.31, no.6, pp. 1003-1009.

Vallejo, L.E., and Liang, R., 1994, "Fracture Mechanics Applied to Geotechnical Engineering."

Vallejo, L.E., and Shettima, M., 1994, "Faults and dam interaction.," Proceedings of the 8th International Conference in Computer Methods and Advances in Geomechanics (IACMAG), Vol. III, pp. 2511-2516, West Virginia University, Morgantown.

Vallejo, L.E., and Zhou, Y., 1994, "Discussion of: Effect of gravel on hydraulic conductivity of compacted soil liners," Journal of Geotechnical Engineering, ASCE, vol.120, no.5, pp. 935-937.

Vallejo, L.E., and Zhou, Y., 1994, "The mechanical properties of simulated soil-rock mixtures," Proceedings of the XII International Conference on Soil Mechanics and Foundation Engineering, Vol. 1, pp. 365-368, New Delhi, India.

Vallejo, L.E., Robinson, M.K., and Stewart-Murphy, A.C., 1994, "The role of share pores in settlement."

Iannacchione, A.T., Sefton, J., and Vallejo, L.E., 1994, "Physical properties of AML landslides in Kentucky: Case studies analyzed," Proceedings of the International Land Reclamation and Mine Drainage Conference, Vol. 4, pp. 153-162, Pittsburgh.

Neufeld, R.D., Vallejo, L.E., Hu, W., Latona, M., Carson, C., and Kelly, C., 1994, "Properties of fly ash content cellular concrete," Journal of Energy Engineering,, vol.120, no.1, pp. 35-48.

Vallejo, L.E., 1993, "Shear stresses and the hydraulic fracturing of earth dam soils," Soils and Foundations, vol.33, no.3, pp. 14-27.

Vallejo, L.E., Alaasmi, A., and Yoo, H., 1993, "Behavior under compression of stiff clays with multiple cracks," Proceedings of the International Symposium on Hard Soils-Soft Rocks, pp. 825-831, Athens, Greece.

Vallejo, L.E., Shettima, M., and Yoo, H., 1993, "The mechanics of formation of the Lake County Uplift at New Madrid," Proceedings of the 1993 National Earthquake Conference, Vol. 1, pp. 247-256, Memphis.

Vallejo, L.E., Welsh, R.A., Lovell, C.W., and Robinson, M.K., 1993, "The influence of fabric and composition on the durability of Appalachian shales."

Vallejo, L.E., 1992, "Liquefaction zones predicted by the type of stresses induced by the ends of fault segments," Proceedings of the 10th World Conference on Earthquake Engineering, Vol. 3, pp. 1355-1359, Madrid, Spain.

Vallejo, L.E., 1991, "A plane stress direct shear apparatus for testing clays."

Vallejo, L.E., 1991, "Closure to discussion of: Fissure parameters in stiff clays under compression," Journal of Geotechnical Engineering, ASCE, vol.117, no.5, pp. 848-849.

Vallejo, L.E., and Shettima, M., 1991, "Crack propagation in clays under dynamic loads," Proceedings of the IX Panamerican Conference on Soil Mechanics and Foundation Engineering, pp. 1303-1314, Viña del Mar, Chile.

Vallejo, L.E., and Shettima, M., 1991, "Fault induced ground deformations and their effect on structures," Proceedings 2nd International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, Vol. II, pp. 1275-1280, St. Louis.

Iannacchione, A.T., and Vallejo, L.E., 1991, "Stress and behavior of material under direct shear," Proceedings of the 32nd U.S. Symposium on Rock Mechanics, pp. 549-558, Norman, Oklahoma.

Welsh, R.A., Vallejo, L.E., Lovell, C.W., and Robinson, M.K., 1991, "The U.S. Office of Surface Mining (OSM) proposed strength-rock durability classification system."

Vallejo, L.E., and Yoo, H., 1990, "The bearing capacity of debris flows," Hydraulics/Hydrology of Arid Lands, R.H. French (ed.), American Society of Civil Engineers, pp. 232-237.

Vallejo, L.E., 1989, "An extension of the particulate model of stability analysis for mudflows," Soils and Foundations, vol.29, no.3, pp. 1-13.

Vallejo, L.E., 1989, "Discussion of: Lateral loads on offshore structures exerted by submarine mudflows," Soils and Foundations, vol.29, no.3, pp. 169-171.

Vallejo, L.E., 1989, "Fissure parameters in stiff clays under compression," Journal, vol.115, no.9, pp. 1303-1317.

Vallejo, L.E., Welsh, R.A., and Robinson, M.K., 1989, "Correlation between unconfined compression strength and point load strengths for Appalachian rocks," Proceedings of the 30th U.S. Symposium on Rock Mechanics, pp. 461-468, Morgantown, West Virginia.

Vallejo, L.E., 1988, "The brittle and ductile behavior of clay samples containing a crack under mixed-mode loading," Theoretical and Applied Fracture Mechanics, vol.10, pp. 73-78.

Vallejo, L.E., 1988, "The liquefaction of sand lenses during an earthquake."

Vallejo, L.E., and DeGroot, R., 1988, "Bluff response to wave action," Engineering, vol.26, no.1, pp. 1-16.

Vallejo, L.E., 1987, "Discussion of: The mechanics of debris flow, by K. Sassa," Proceedings of the XI International Conference on Soil Mechanics and Foundation Engineering, Vol. 5, pp. 2709, San Francisco.

Vallejo, L.E., 1987, "Evaluation of test methods designed to obtain the undrained shear strength of muds," Marine Geotechnology, vol.7, no.3, pp. 173-188.

Vallejo, L.E., 1987, "Fissure-water interaction in earth dams," Proceedings of the VIII Panamerican Conference on Soil Mechanics and Foundation Engineering, Vol. 2, pp. 405-416, Cartagena, Colombia.

Vallejo, L.E., 1987, "The brittle and ductile behavior of a material containing a crack under mixed-mode loading," Proceedings of the 28th U.S. Symposium on Rock Mechanics, pp. 383-390, Tucson, Arizona.

Vallejo, L.E., 1987, "The influence of fissures in a stiff clay subjected to direct shear," Geotechnique, vol.37, no.1, pp. 69-82.

Welsh, R.A., Vallejo, L.E., and Robinson, M.K., 1987, "Evaluation of the durability testing techniques for rock under-drain material used in Appalachian surface coal mining valley fills," Proceedings of the 1st International Symposium on Flow Through Drains, Sponsored by the Province of British Columbia Ministry of Energy, Mines and Petroleum Resources, pp. 83-93, Cranbrook, B.C., Canada.

Vallejo, L.E., 1986, "Mechanics of crack propagation in stiff clays."

Vallejo, L.E., 1986, "The mudslide profile method to measure the undrained shear strength of muds."

Vallejo, L.E., 1985, "Fissure parameters and the progressive failure of slopes," Proceedings of the XI International Conference on Soil Mechanics and Foundation Engineering, Vol. 4, pp. 2353-2356, San Francisco.

Vallejo, L.E., 1984, "Analysis of the mobilization of submarine mudslides," Proceedings of the IV International Symposium on Landslides, Vol. 2, pp. 361-366, Toronto, Canada.

Vallejo, L.E., and Pramono, E., 1984, "Development of fracture regions in brittle materials," Proceedings of the 25th U.S. Symposium on Rock Mechanics, Chapter 6, pp. 47-54, Northwestern University, Evanston.

Baladi, G.Y., Vallejo, L.E., and Goitom, T., 1983, "Normalized characterization model of pavement materials."

Vallejo, L.E., 1982, "Development of a shear zone structure in stiff clays," Proceedings of the 4th International Conference on Numerical Methods in Geomechanics, Vol. 1, pp. 255-262, Edmonton, Alberta, Canada.

Vallejo, L.E., 1982, "Evaluation of test methods designed to obtain the undrained shear strength of muds," Proceedings of the 14th Annual Offshore Technology Conference, Vol. 3, pp. 11-20, Houston, Texas.

Vallejo, L.E., 1982, "The effect of freeze-thaw cycles on the structure and the stability of soil slopes," Proceedings of the 3rd International Symposium on Ground Freezing, Vol. 1, pp. 455-461, Hanover, New Hampshire.

Vallejo, L.E., and Tarvin, P.A., 1982, "A new method to determine the undrained shear strength of muds based on Plasticity Theory," Proceedings of the 3rd International Conference on Behavior of Offshore Sturctures, Vol. 2, pp. 464-473, MIT, Cambridge.

Vallejo, L.E., 1981, "Determination of the shear strength of granulo-viscous material using the vane shear apparatus and the two-phase suspension theory," Studies in Applied Mechanics, Mechanics of Structured Media- Part B, Elsevier, A.S. Selvadurai, ed., pp. 373-381.

Vallejo, L.E., 1981, "Stability analysis of mudflows on natural slopes," Proceedings of the X International Conference on Soil Mechanics and Foundation Engineering, Vol. 3, pp. 541-544, Stockholm.

Vallejo, L.E., and Edil, T.B., 1981, "Stability of thawing slopes: Field and theoretical investigation," Proceedings of the X International Conference on Soil Mechanics and Foundation Engineering, Vol. 3, pp. 545-548, Stockholm.

Vallejo, L.E., and Peszek, L.M., 1981, "Analysis of the stresses in seismically induced shallow slope failures," Proceedings of the 1st International Conference, Vol. 1, pp. 551-556, St. Louis.

Vallejo, L.E., 1980, "A new approach to the stability analysis of thawing slopes," Canadian Geotechnical Journal, vol.17, no.4, pp. 607-612.

Vallejo, L.E., 1980, "Analysis of wave induced erosion of cohesive soils forming coastal bluffs," Proceedings of the 1st Canadian Coastal Conference, National Research Council of Canada, Burlington, pp. 220-228, Ontario, Canada.

Vallejo, L.E., 1980, "Discussion of: Cliff collapse and rock avalanches in the Mackenzie Mountains, northwestern Canada," Canadian Geotechnical Journal, vol.17, no.1, pp. 149-152.

Vallejo, L.E., 1980, "Mechanics of mudflow mobilization in low-angled clay slopes," Engineering Geology, vol.16, pp. 63-70.

Edil, T.B., and Vallejo, L.E., 1980, "Mechanics of coastal landslides and the influence of slope parameters," Engineering Geology, vol.16, pp. 83-96.

Shettima, M., and Vallejo, L.E., 1980, "Crack propagation and interaction in stiff clays forming part of earth dams."

Vallejo, L.E., 1979, "An explanation for mudflows," Geotechnique, vol.29, no.3, pp. 351-354.

Vallejo, L.E., and Edil, T.B., 1979, "Design charts for development and stability of evolving slopes," Journal of Civil Engineering Design, vol.1, no.3, pp. 231-252.

Vallejo, L.E., 1978, "Discussion of: A limit equilibrium analysis of progressive failure in the stability of slopes," Canadian Geotechnical Journal, vol.15, no.4, pp. 617-618.

Edil, T.B., and Vallejo, L.E., 1977, "Shoreline erosion and landslides in the Great Lakes.," Proceedings of IX International Conference on Soil Mechanics and Foundation Engineering, Vol. 2, pp. 51-57, Tokyo.

2012, "Pre-Columbian Engineering," SHPE Conference 2012, Fort Worth, Texas.

2008, "Pre-Columbian Engineering," Department of Civil Engineering, Universidad de los Andes, Bogotá, Colombia.

2003, "Crushing of granular bases: fractal and laboratory analyses," Keynote Lecture, XIV Colombian Symposium on Pavements Engineering, Department of Civil Engineering, Universidad del Cauca, Popayán, Colombia.

2003, "Shear strength parameters and surface instabilities associated with mudflows," Paper and lecture, International Workshop on: Occurrence and Mechanisms of Flows, Sorrento, Italy.

2002, "The application of fractals and fracture mechanics in geotechnical engineering," Keynote Lecture, IX Colombian Geotechnical Congress, Congress organized by the Colombian Geotechnical Society, Bogota, Medellin, Colombia.

1999, "Analysis of the stability of natural slopes using fracture mechanics theory," Keynote Lecture, VI Civil Engineering Symposium: Challenges in the Construction of Civil Engineering Works, Department of Civil Engineering, Instituto Tecnologico de Monterrey, Monterrey, Mexico.

1999, "Fractal Pores and the degradation of shales," 4th International Conference on Fractals in Engineering," Delft University, Delft, Conference organized by the Institut National de Recherche en Informatique et en Automatique (INRIA) at Rocquencourt, France, The Netherlands.

Vallejo, L.E., Neufeld, R.D., Golden, D.M., Hu, W., and Kelly, C., 1995, "The influence of the pore structure on the physical properties of ash derived cellular concrete," American Concrete Institute, Spring Meeting, Salt Lake City.

Neufeld, R.D., Vallejo, L.E., Hu, W., Latona, M., Carson, C., and Kelly, C., 1994, "Environmental and physical parameters of high ash content autoclaved cellular concrete block," 87th Annual Meeting of the Air and Waste Management Association, Cincinnati, Ohio.

1992, "Earth fissures resulting from earthquakes and subsidence," Honors College Lecture Series, University of Pittsburgh.

1991, "Landslides in the Great Lakes," Soil Mechanics Seminar Series, Engineering Department, Soil Mechanics Group, Cambridge University, Cambridge, England.

1989, "Mechanics of the evolution of coastal slopes," Department of Civil Engineering, Colombian National University, Bogotá.

1987, "The influence of fissures in stiff clays under direct shear," Symposium on the Engineering Application of Direct and Simple Shear Testing, The British Geotechnical Society, Institution of Civil Engineers, London.

1985, "Fissure parameters and progressive failure of slopes," Session 9A: Geological Aspects of Geotechnical Engineering (Dr. S. Cavounides, Organizer). 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco.