Check out recent article: “A New Approach for the Design of Micropiles in Tension” published in the most recent issue of the DFI magazine (Sept/Oct 2019) about a modified design procedure developed by local geotechnical firm American Geotechnical & Environmental Services, Inc.
Article can be found in following link: contact Sebastian Lobo-Guerrero, PH.D.,P.E. with questions. email@example.com
https://dfi.dcatalog.com/v/September-October-2019/?page=89 (DFI magazine is a public publication not associated with ASCE publications)