Area Engineer Tensar CMC Alpharetta, Georgia, United States
Description of the Presenter’s Qualifications and Credentials : BS + MS Civil Engineering Geotechnical Engineer Registered PE in MI, MN, IL, OH, MD, and DE Provide engineering support for geogrid usage in eastern Canada, the northeast, and Great Lakes region of United States Experienced with numerous offshore wind port projects to optimize cross section design.
Summary of the Course Content: The performance of unbound aggregate surfaces is a function of the thickness of the unbound aggregate layer, the strength of the subgrade, and the traffic loading conditions. Performance is generally in terms of overall bearing capacity when cranes are being considered, or surface rutting for reacher stackers, self-propelled modular transport units, and other vehicles. A new design methodology has been developed to reliably & economically determine the required aggregate thickness.
This course will explain the design method. The design method quantifies the transfer of the load from the gravel surface to the subgrade and denotes this parameter as the variable "T". T is a function of the friction angle of the aggregate, the shear strength of the subgrade, the effective pressure of the aggregate on the subgrade, and if a tested geogrid is present. The bearing capacity of the gravel surface can be determined with T and is a vital parameter for the safe operation cranes at ports. The accumulation of rut from repetitive loading can then be calculated for both the gravel and subgrade independently and then summed for total rut depth. Rut accumulation is a function of the mobilized bearing capacity relative to the ultimate bearing capacity of the gravel and subgrade layers and is calculated for one vehicle pass. Then a logarithmic or power function, depending on soil type, is applied to determine rut depth from N number of vehicle passes. Preventing excessive rut depth minimizes maintenance costs and is vital to the successful operation of unpaved port facilities.
The effect of different subgrade types including reclaimed dredged material, the contact area of tires, testing geogrid, full scale validation of finite element models, and how the cost & embodied carbon of projects can be impacted with the design method will also be discussed.
This design method was recently used to reduce gravel thickness on the Port of Albany project, is included in the Deep Foundation Institute's Working Platform Design Guide, and was recently published in the Journal of Transportation Geotechnics.
Discussion of the Applicability of the Course to the Topics of the Conference : This course is applicable to the Port Engineering and Environmental Sustainability topics because the design method has successfully been implemented with a geogrid to reduce costs on the Port of Albany project. Similar approaches are currently being considered by bidding contractors on other port projects to provide a "Value-Engineered" alternative. In addition to cost savings, this design methodology has reduced schedule and embodied carbon of projects.
Target Audience for the Course : Geotechnical Engineers, Contractors, and Facility Owner Operators.
Description of the Benefit of the Course to Conference Attendees : Attendees will learn how to design unpaved surfaces for port loading conditions and how to evaluate the suitability of a geogrid. Attendees will learn how this design method can be used to reduce cost, schedule, and embodied carbon on their projects. 4 Professional Development Hours
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