Date of Award
Master of Engineering Science
Civil and Environmental Engineering
Dr. Sean Hinchberger
This thesis examines: (i) the response of reduced-scale micropiles and (ii) the pullout capacity of grouted tieback anchors in cohesionless soil. The primary objectives are to investigate how micropiles and grouted tiebacks obtain their compressive and pull-out capacity, respectively, to assess current design practices for micropiles and to correlate the pull-out capacity of grouted tieback anchors to standard penetration test (SPT) N- values, referring to American Society for Testing and Materials (ASTM D1586) and construction method. To achieve these objectives, the following tests were conducted and/or evaluated: (i) compression load tests on reduced-scale micropiles constructed in sand, and (ii) pull-out tests on full-scale grouted anchors constructed in sand and silt. Thirty-two reduced-scale micropiles were constructed in cohesionless soil and load tested to failure to assess the adequacy of current Federal Highway Administration (FHWA) design methods for micropiles. Six of these reduced-scale micropiles were constructed in cohesionless soil with earth pressure cells in the sand to assess the stress regime around the micropiles during loading. Finally, the pullout capacity of 78 grouted anchors installed in cohesionless soil was assessed from full-scale tieback anchor tests and the capacity is correlated to basic soil parameters. The results reported in this thesis highlight the importance of interface friction and dilatancy as well as the stiffness of the soil surrounding micropiles and anchors.
Urian, Cosmin Dan, "The Behaviour of Micropiles and Tiebacks in Cohesionless Soils" (2009). Digitized Theses. 3981.