huangyhg

bracing of piles
i don't know about the slab but retaining walls are usually constructed at or below grade to retain fill. as such the pile are usually entirely below grade and bracing is not only unecessary it is impractical.
as for the floor slab, the same would be true if the slab were placed on grade yet supported on pile. something that's been referred to as a "land pier".
it appears that the code is addressing stability both globally and local. however if your pile are not unbraced for some height above ground, then the soil will act to brace each pile.
i agree with qshake, but your geotechnical engineer should review the soil for potential liquefaction. under some seimic conditions the jello we call soil could lose some stiffness. this could pose a problem, requiring grade beams or the like to connect the pile caps.
regarding liquefaction, concerns for this type of soil failure really need to extend beyond the structure. soil remediation (dynamic compaction, stone columns etc) would be an effective and likely solution but not bracing pile. re
the bracing of the pile caps is done using tie beams if not braced by a floor diaphragm. most seismic codes require tie beams.

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