Lelio Mejia, Ph.D., P.E., G.E. (California) and Jintai Wang, Ph.D., (Virginia) will present at Geo-Congress 2019 at the Pennsylvania Convention Center in Philadelphia on March 24 – 27, 2019.
Lelio will present "The Panama Canal: A Wonder of Engineering" and Jintai will present "The Effect of Shaking History on Liquefaction Resistance of Sand Deposit Using Shake Table Testing."
Lelio is a Senior Principal Engineer based in California with more than 35 years of experience in geotechnical and earthquake engineering. For many years, he has focused on the challenges of dam and levee engineering and is a leading international authority in this field, with emphasis on the seismic design and performance of dam structures. Lelio leads Geosyntec's western U.S. dams and levees practice and is a registered civil and geotechnical engineer.
Jintai specializes in geotechnical engineering and soil liquefaction, with experience focused on projects such as retaining walls, reinforced soil slopes, and slope stability and settlement problems spanning a wide variety of geographic areas and geologic conditions. He has experience planning and performing subsurface exploration using drilling methods, as well as performing geotechnical and project risk assessments and proposing mitigation alternatives.
Geo-Congress 2019, the Eighth International Conference on Case Histories in Geotechnical Engineering, will continue the series of international conferences, bringing together researchers, practitioners, students and policy makers from around the globe to share their geo-accomplishments and carry on the tradition of using case histories to cultivate engineering judgment espoused by Terzaghi, Peck, Prakash, and other geoengineers.
Title: The Panama Canal: A Wonder of Engineering
Presenter: Lelio Mejia, Ph.D., P.E., M.ASCE
Track: Geo-PIT: Plenary Session on Powerful, Informative Talks on Geotechnical Topics
Time: 8:30 – 10:00 a.m., March 25, 2019
Location: Terrace Ballroom IV
Abstract: The Panama Canal changed the world economically, politically, and socially by changing global trade routes, the underpinnings of world commerce. It provided a cost-effective alternative to the railroads in the U.S. and changed Panama's economy along with that of other regions. Engineers used the latest technology in civil, mechanical, and electrical engineering and construction to overcome multiple design and construction challenges. The project entailed the biggest concrete structures, the deepest channel excavations, and the largest dam and reservoir made by 'man' as of the turn of the 20th century. Perhaps the most challenging aspect of the Canal's original construction was excavation of the Gaillard Cut, which allows ships to cross the mountain range of Panama. Approximately 35 percent of the excavated volume was from the multiple slides that plagued the excavation since its early stages and that made infamous the cut and the weak rocks that form its slopes.
Over the years, the Canal has performed very well but, having reached capacity, it was expanded between 2006 and 2016. The expansion project included construction of two new sets of locks at the Pacific and Atlantic entrances, four dams to create a new access channel on the Pacific side and widening and deepening of the Gaillard Cut. The Canal remains one of the major achievements of the Civil Engineering profession and a testimony to the ingenuity and dedication of engineers.
Title: The Effect of Shaking History on Liquefaction Resistance of Sand Deposit Using Shake Table
Presenters: Jintai Wang, Geosyntec Consultants; Sajjad Salam, The Pennsylvania State University; Ming Xiao, The Pennsylvania State University
Track: Earthquake Engineering and Soil Dynamics: Laboratory Testing
Time: 10:35 a.m. – 10:47 a.m., March 26, 2019
Location: Room 123
Abstract: Previous research shows that shaking history affects the liquefaction resistance of the soil. A strong shaking event could reduce the soil liquefaction resistance due to increased anisotropy of soil. A mild shaking with partial or no liquefaction could increase the liquefaction resistance. In this research, the effect of shaking history on liquefaction resistance of sand was studied using a series of 1-g shake table testing. A uniform liquefiable sand deposit was air-pluviated and saturated in a large laminar shear box (L×W×H: 2.29 m × 2.13 m × 1.83 m). The sand deposit was subjected to four different shaking stages. Piezometers were embedded at different depths to record the pore pressure during and after each shaking. The excess pore pressure readings from four shaking stages were compared to investigate the effect of shaking history on liquefaction resistance of the sand deposit. The major findings of this paper are: (1) Along with the shaking, the sand deposit became denser (2) The shaking event with an amplitude of 0.25 g tended to densify the sand and increase the liquefaction resistance (3) The strong shaking with an amplitude of 0.4 g tended to weaken the soil structure and reduce the liquefaction resistance.
About the event: https://www.geocongress.org/
View the final Program: GEO-CONGRESS 2019 Final Program
Learn more about Lelio: https://www.geosyntec.com/people/lelio-mejia
Learn more about Jintai: https://www.linkedin.com/in/jwangengr/