ASCE has honored the writing team of Beena Ajmera, Ph.D., P.E., M.ASCE; Thomas L. Brandon, Ph.D., P.E., M.ASCE; and Binad Tiwari, Ph.D., P.E., F.ASCE, with the 2020 Thomas A. Middlebrooks Award for the paper “Characterization of the Reduction in Undrained Shear Strength in Fine-Grained Soils Due to Cyclic Loading,” which appeared in the May 2019 issue of Journal of Geotechnical and Geoenvironmental Engineering.
The degradation in undrained shear strength in silts and clays causes slope instabilities or leads to lateral spreading and settlements. Notable examples of failures induced by degradation in undrained shear strength include the Fourth Avenue Landslide in Anchorage following the 1964 Alaska Earthquake, the damage at the Moss Landing Marine Laboratory following the 1989 Loma Prieta Earthquake, ground failure at Wufeng, Taiwan, after the 1999 Chi-Chi Earthquake, the landslide movement at Lokanthali after the 2015 Gorkha, Nepal, Earthquake and the Vine Road Embankment failure after the 2018 Anchorage Earthquake. The subject paper presented the results of an extensive laboratory testing program on field samples and clay mineral mixtures, from which the first systematic evaluation of the post-cyclic undrained shear strength of fine-grained soils in terms of the clay mineralogy and plasticity characteristics was performed. The results from the laboratory testing program permitted the development of several significant relationships that designers may use in practice.
Ajmera is an assistant professor at North Dakota State University.
The Thomas A. Middlebrooks Award is made to the author or authors of a paper published by the Society judged worthy of special commendation for its merit as a contribution to geotechnical engineering. Papers written by young engineers are given preference.
