Abstract: A terrace house located on coastal beach of Shandong Province, with waffle-slab raft foundation, is founded on 3.5~5.0 m thick miscellaneous fill treated with dynamic compaction, which is followed by 3.0 thick mucky soil, forming a hard-soft double-layered foundation.When the construction of the building was approaching completion, large settlement and differential settlement occurred.The causes of the settlements were analyzed from the geological conditions, foundation treatment measures, the design concept and construction procedure, and through comparing calculated settlement with the measured one, the experience coefficient for the settlement was obtained.In order to control post-construction settlement and differential settlement, micro-pile was adopted and its effectiveness is illustrated by comparing the calculated settlement of raft foundation to the piled raft foundation with a few of piles as settlement reducer.The foundation deformation tended to be stable within two weeks after the ground treatment completion, thus achieving the planned expectation.