The topic for GSI’s monthly seminar on Wednesday, June 8 (11:30 a.m.–1 p.m. ET), is “Sand Drains-to-Wick Drains-to-Sand Columns.”
This webinar begins with Terzaghi’s consolidation work (extended by Barron) leading directly to consolidation of saturated soils using the technique of sand drains. It then describes a case history failure resulting in a $6M judgment against the design consultant. This project (and greater economic efficiency) led directly to the use of wick drains, also called prefabricated vertical drains or simply PVDs. They are described and illustrated along with concerns of kinking and smear. The requisite research design is numerically illustrated to arrive at a satisfactory factor-of-safety flow value. This body of work on drainage, however, has a direct relationship on stability of soft soils using the technique of sand columns. Now using columns of sand encased in a geotextile we have a method to both simultaneously drain soft saturated soils and stabilize the site against shear failure as occurred in the case history cited previously. The technology, including its installation, has indeed come full circle.
Participants will learn one-dimensional vertical consolidation (K. Terzaghi) and its extension to radial flow (R. Barron) of soft saturated soils. The classical method of draining such soils by sand drains is illustrated by a case history. Unfortunately, the site failed, resulting in major litigation which was ugly to say the least. However, the introduction and use of wick drains (aka, PVDs) has completely taken over this application. Issues of kinking and smear will be addressed along with FS-design for flow rate and dewatering. These soft soil sites are indeed sensitive to shear failures and by using the classical sand drain installation method now with a geotextile encased sand column we have both drainage and stability.
Public and private owners of transportation, geotechnical, hydraulic, and environmental facilities; consultants and designers in the private sector; regulators and agency personnel at the federal, state, and local levels; geosynthetic manufacturers and their representatives; geotechnical and geosynthetic testing organization personnel; contractors and installers of geosynthetic systems; academic and research groups; others desiring technically related information on this aspect of our constructed environment.
Dr. Robert M. Koerner, professor emeritus of civil engineering at Drexel University and director emeritus of the Geosynthetic Institute, has had an interest in geosynthetics spanning more than 30 years of teaching, research, writing, and advising. He holds his Ph.D. in geotechnical engineering from Duke University. He is a registered professional engineer (P.E.) in Pennsylvania, a Distinguished Member of ASCE, a Diplomate of the GeoInstitute, and a member of the National Academy of Engineering. Bob has authored and co-authored about 700 papers on geosynthetics and geotechnical topics in journals and at national and international conferences. His most widely used publication is the sixth edition of the textbook Designing with Geosynthetics. He is the founding director of the Geosynthetic Institute, a nonprofit research and development organization dedicated to the proper use of geosynthetics in its myriad applications. The institute also provides laboratory accreditation and inspection certification programs.
GSI webinars are offered on the second Wednesday of each month (11:30 a.m.–1 p.m. ET) for members ($200) and non-members ($250).
The topic for the next webinar (July 13) is: “In-Situ Stabilization of Slopes Using Geosynthetics and Soil Nails.”