(Received 8 August 2014; accepted 12 November 2015)
Published Online: 2016
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Drilled shaft foundation elements provide a cost-effective foundation alternative for the support of building and bridge superstructure loads. Bi-directional pile loading tests (BDPLTs) to evaluate the capacity of drilled shafts have become popular owing to their capacity to save time and effort as compared to the use of top-down loading tests. However, the use of BDPLTs requires that production shafts be post-grouted following testing in order to assure appropriate in-service performance. Commonly used single-acting loading cells and/or loading cell construction details can pose the potential for the development of voids following post-grouting due to their monotonic jacking action and large footprint. This paper described the development and use of high pressure bi-directional loading cells intended to minimize the possibility of post-test construction defects. First, a comparison was made between the single-acting and double-acting loading cells. Second, the results of laboratory calibrations on the pressurized loading cells were performed, as were component testing of the pumps, hoses, and hydraulic fluid synchronization lines. Then, the use of the new high pressure double-acting loading cells in production testing of instrumented shafts was described, and the efficacy of the new loading cells was illustrated. The new loading cells provided the profession with a load cell alternative for conducting BDLTs and should serve to help reduce the risk of post-test grouting defects in drilled shaft foundations.
Professor, Department of Civil Engineering, Kyungsung Univ., Busan,
President, G-Tec Engineering Co. Ltd., Busan,
Nam, Moon S.
Senior Researcher, Korea Expressway Corporation, Hwasung,
Professor, Department of Civil Engineering, Korea Maritime and Ocean Univ., Busan,
Stuedlein, Armin W.
Associate Professor, Oregon State Univ., Corvallis, OR
Stock #: GTJ20140166