Industry Survey of State of Practice for Helical Piles and Tiebacks-Article

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The article reports a 2013 industry survey commissioned by the Deep Foundations Institute’s Helical Piles and Tiebacks Committee to assess current applications, design, installation, perceived needs, and future trends. It received 206 responses, mainly from geotechnical engineers and contractors, with most respondents’ work in North America.<br /><br />Nearly 80% of respondents had used helical piles or anchors. Common applications included foundations for new construction, repair of existing foundations, and tiebacks or lateral earth support. Respondents reported use across many soil types, including engineered fill, clays, sands, and gravel; cobbles and boulders, very soft clays, and potentially liquefiable loose soils were more often cited as problematic.<br /><br />Common design approaches included the Individual Plate and Cylindrical Shear methods, alongside installation-torque correlations. Torque was measured during installation on most respondents’ projects, but load testing was less consistent. Practices also varied in site investigation, inspection, safety factors, and interpretation of load-test results. The authors identify this variability, along with limited well-documented full-scale field data paired with reliable geotechnical information, as a barrier to more consistent and widespread acceptance.<br /><br />The leading research priorities were improving torque-to-capacity correlations, determining lateral resistance, and refining uplift and bearing-capacity estimates. Other needs include understanding seismic and dynamic loading, corrosion, buckling, long-term deformation, and the behavior of larger helices and shafts.<br /><br />The authors recommend clearer guidance for site investigations, updated torque-correlation research, and publication of full-scale project data that combines soil profiles, installation records, and load-test results. They also call for better torque documentation, more appropriate load testing and interpretation, and education for engineers, inspectors, agencies, and owners. Overall, the survey portrays helical foundations as an established and versatile technology with strong industry support, but stresses that stronger evidence and more consistent practice are needed to advance design reliability and acceptance.

Keywords

helical piles

tiebacks

deep foundations

geotechnical engineering

torque correlations

load testing

foundation design

soil conditions

installation practices

industry survey