Contractor is responsible for design of temporary ERS for a launching and receiving shaft for a sewer tunnel.  Inside diameter 35 feet and excavation depth 42 feet.  Contractor proposing a secant pile wall with 2 foot diameter auger cast piles, every other pile steel reinforced.  His design analysis is based on a lateral load pile program, and further supplemented with a structural software program modeling the ERS shaft as a concrete tank below ground.  Has anyone ever heard or seen an attempt to model/analyze a circular ERS shaft in this manner?

No direct experience on this. Just a little thought.

1. The pile is critical at driving/construction stage only.
2. Upon completion, the pile wall subjects to axial compression mainly, if properly aligned.

Looks like his method is ok (to me).

Whalers and bracing are critical in maintianing the piles as an integral unit.