American Society of Civil Engineers


Settlement of Coal-Fired Power Plant Foundations on Arid Soils


by José L. M. Clemente, M.ASCE, (Principal Geotechnical Engineer, Bechtel Power Corporation, 5275 Westview Drive, Frederick, MD 21703 E-mail: jlclemen@bechtel.com), Jeffrey O’Neal, (Engineering Group Supervisor, Bechtel Power Corporation, 5275 Westview Drive, Frederick, MD 21703 E-mail: joneal@bechtel.com), and Charles G. Worthington, (Assistant Project Engineer, Bechtel Power Corporation, 5275 Westview Drive, Frederick, MD 21703 E-mail: cworthin@bechtel.com)
Section: Geotechnical Engineering for Building Foundations/Slabs on Unsaturated Soil, pp. 379-390, (doi:  http://dx.doi.org/10.1061/40802(189)27)

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Document type: Conference Proceeding Paper
Part of: Unsaturated Soils 2006
Abstract: A new 400 MW coal-fired power generating unit was planned to be constructed next to two existing units in the desert of central-eastern Arizona. An expansive clay layer was encountered at depth within the site of the two existing units. The clay layer was stiff to hard, and groundwater was located several hundred meters below the ground surface at the site. However, previous foundation heave experience obtained from another power plant built to the north of the site in the late 1970s/early 1980s led the designers to use drilled piers installed to a depth of about 24 m to support the two existing units. An extensive subsurface investigation program performed at the site of the new unit revealed the presence of alluvial sands and gravelly sands to a depth of about 8 m, where the top of the clay layer was encountered. Based on the results of field and laboratory tests and geotechnical analyses, it was decided to support the new unit using footings and structural mats placed directly on the alluvial soils. The use of these shallow foundations would result in significant schedule and cost savings for the project. Detailed foundation settlement monitoring for more than 1 year during plant construction indicated excellent foundation settlement performance and the adequacy of the selected foundation system.


ASCE Subject Headings:
Arid lands
Foundation settlement
Industrial facilities
Power plants