Shallow Foundations for Tall Structures in Florida

The use of shallow foundation systems with measurable but tolerable settlement of major building complexes constructed in the Miami, Florida area is demonstrated by three case histories, The Omni International, Turnberry Isle Complex, and the James L. Knight Convention Center. Subsurface exploration programs included conventional borings, static cone penetrometer tests, and large diameter coring of soft limerock zones. The compressibility of the subsurface materials can be confidently estimated through the proper interpretation of the field test results and the results of full scale instrumented preloads at geologically similar sites. High-rise structures can be constructed on shallow foundation systems with acceptable settlement behavior. The structures will have measurable but tolerable settlements. Settlements tend to become intolerable when the structures exceed 10 to 15 stories. However, effective precompression of the underlying soils by preloading can be achieved within a few weeks. This reduces total and differential settlements to tolerable limits and makes shallow foundation systems economically desirable for high-rise structures.