lowering top of grade near ex grade beam

huangyhg

lowering top of grade near ex grade beam
i have a client who wants to reduce finished grade elevation near an existing cip grade beam.  frost depth here is 3'.  lowering grade will make the existing grade beam bottom (on one side of the beam) to be within 1'-8" of top of fin grade.  using traditional underpinning to deepen the grade beam is not feasible because the subgrade is poor fill which will definitely allow the underpinning to settle.
i can dowel to the underside of the grade beam and add concrete   
to its bottom, (which will be costly) but wonder what others have done in a similar situation.  
sounds like an application for a frost protected shallow foundation.  see