Research


The following is a concise overview of the research that the group is involved with. It is organized by topics, but of course there is a necessary overlap among topics. Credit must be given to the students, visitors, and faculty collaborators who have worked with us and have pushed the field forward.

Fracture Mechanics
Discontinuous Media
Autoadaptive Systems
Analytical and Numerical Models
Soil-Structure Interaction
Tunnels
Problem Soils
Extreme Events
Current Projects

Autoadaptive Systems

This research explores the application of thixotropic fluids such as water and bentonite mixtures as an autoadaptive passive design methodology in geotechnical engineering to prevent or to reduce the risk of liquefaction in granular soils. Mitigation of liquefaction damage can decrease the loss of lives and economic loss that occur during an earthquake.

Static and cyclic triaxial tests and resonant column tests are conducted to evaluate the changes of liquefaction potential and of characteristic soil properties of a clean sand with the addition of bentonite.

The tests indicate that for CSR=0.15, 2% or less bentonite has negligible influence on the liquefaction behavior, but 5% bentonite dramatically increases the liquefaction resistance. Resonant column tests suggest that this effect is associated with the increase in the elastic threshold and the reduced stiffness degradation observed at small strains.
Drnevich resonant column apparatus
  • Haldavnekar, V., Bobet, A., Santagata, M., and Drnevich, V. (2003). Soil Treatment with a Thixotropic Fluid: An Autoadaptive Design for Liquefaction Prevention. Proceedings of the 11th International Conference on Soil Dynamics & Earthquake Engineering and 3rd International Conference on Earthquake Geotechnical Engineering, Vol. II, pp. 553-560.

  • El-Mohtar, C., Bobet, A., Santagata, M., Drnevich, V., and Johnston, C. (2008). Cyclic response of Sand with Thixotropic Pore Fluid. ASCE Geotechnical Earthquake Engineering and Soils Dynamic Conference. GSP-181, CD-ROM Proceedings, 10 pp.

  • El-Mohtar, C., Santagata, M., Bobet, A., Drnevich, V., and Johnston, C. (2008). Effect of Plastic Fines on the Small Strain Stiffness of Sand. IS-Atlanta: Fourth International Symposium, Deformation Characteristics of Geomaterials, Atlanta, GA. Burns et al., editors, IOS Press, The Netherlands, Vol. 1., pp. 245-251.

  • Witthoeft, A.F., Santagata, M.C., and Bobet, A. (2012). Numerical Study of the Effects of Bentonite Treatment for Liquefaction Mitigation. Geocongress 2012“ State of the Art and Practice in Geotechnical Engineering, Oakland, California. CD-ROM Proceedings.

  • El Mohtar, Ch., Bobet, A., Santagata, M.C., Drnevich, V.P., and Johnston, C. (2013). Liquefaction Mitigation using Bentonite Suspensions. ASCE Journal of Geotechnical and Geoenvironmental Engineering, Vol. 39, No. 8, pp. 1369-1380.

  • El Mohtar, C.S., Drnevich, V.P., Santagata, M.C. Bobet, A. (2013). Combined Resonant Column and Cyclic Triaxial Tests for Measuring Undrained Shear Modulus Reduction of Sand with Plastic Fines. Geotechnical Testing Journal, Vol. 36, No. 4, pp. 484-492.

  • El Mohtar, C.S., Bobet, A., Drnevich, V.P., Johnston, C., and Santagata, M.C. (2014). Pore Pressure Generation in Sand with Bentonite: from Small Strains to Liquefaction. Geotechnique, Vol. 64, No. 2, pp. 108-117.

  • Santagata, M.C., Clarke, J.P., Bobet, A., Drnevich, V.P., El-Mohtar, C.S., Huang, P.-T., Johnston, C.T. (2014). Rheology of concentrated bentonite suspensions treated with sodium pyrophosphate for application in mitigating earthquake-induced liquefaction. Applied Clay Science, Vol. 99, pp. 24-34.

  • El Howayek, A., Bobet, A., Johnston, C., Santagata, M., and Sinfield, J. (2014). Microstructure of Sand-Laponite-Water Systems using Cryo-SEM. 2014 Geo-Congress: Geo-Characterization and Modeling for Sustainability, Atlanta, GA.

  • Ochoa-Cornejo, F., Bobet, A., Johnston, C.T., Santagata M. and Sinfield, J.V. (2014). Liquefaction 50 years AFTER Anchorage 1964; how nanoparticles could prevent it. Tenth U.S. National Conference on Earthquake Engineering. Frontiers of Earthquake Engineering, Anchorage, Alaska.

  • Santagata, M., Bobet, A., El Howayek, A., Ochoa, F., Sinfield, J.V., and Johnston, C.T. (2014). Building a Nanostructure in the Pore Fluid of Granular Soils. International Symposium of Geomechanics from Micro to Macro, IS-Cambridge 2014, Cambridge, UK, 1-3 September 2014.

  • Santagata, M., Ochoa-Cornejo, F., Bobet, A., Johnston, C.T., and Sinfield, J.V. (2016). Cyclic behavior and pore pressure generation in sands with laponite, a superplastic nanoparticle. Soil Dynamics and Earthquake Engineering, Vol. 88, pp. 265-279.

  • Santagata, M., Ochoa-Cornejo, F., Bobet, A., Johnston, C. and Sinfield, J. (2017). Discussion on “Laboratory investigation of liquefaction mitigation in silty sand using nanoparticles” [Eng.Geol.204:23-32]. Engineering Geology, Vol. 216, pp. 161-164.

  • Ochoa-Cornejo, F., Bobet, A., Johnston, C., Santagata, M. and Sinfield, J.V. (2019). Dynamic Properties of a Sand-Nanoclay Composite. Geotechnique, https://doi.org/10.1680/jgeot.18.P.017.