It seems to me that the way the pipe pile resists shear would depend on the length of the pile and the fixity conditions. Typically, I would imagine that the soil around the pile would deform/fail before the pile does.
There are many references on the behavior of piles (and the soil-pile system) subjected to lateral loading. Good introductions to the subject might be FHWA HI-97-013 Design and Construction of Driven Piles and FHWA SA-91-048 COM624P User's Guide - both available as a free download from FHWA at
Unfortunately, an often-cited older work, FHWA IP-84-11 Handbook on Design of Drilled Shafts Under Lateral Load, is not currently available electronically.
Are you talking structural design? Jeff is correct that the soil usually deforms before the pile does, unless you have the pile socketed into hard rock or through soft soil into very hard soil and have large lateral loads or if it a marine application.
Donald P. Coduto's "Foundation Design" book has a good section on structural design of concrete filled pipe piles.
