Multi-piece pre-assembled raft foundation and construction method thereof

A pre-assembled raft foundation, comprising:

• a plurality of bottom layer rebars of a foundation slab including a plurality of bottom layer sections and a plurality of first vertical sections connected to the bottom layer sections wherein the bottom layer sections and the first vertical sections are composed of a plurality of U-shaped rebars and a plurality of steel bars disposed on the U-shaped rebars;
• a plurality of foundation steel columns disposed on the bottom layer sections and including a plurality of columns and a plurality of vertical sections disposed at tops of the columns;
• a plurality of upper layer rebars of the foundation slab disposed on the bottom layer rebars of the foundation slab and including a plurality of top layer sections and a plurality of second vertical sections connected to the top layer sections wherein the top layer sections and the second vertical sections are composed of a plurality of U-shaped rebars and a plurality of steel bars disposed on the U-shaped rebars;
• and
• a plurality of foundation rebars disposed on a side of the foundation steel columns and including a plurality of beams and columns, a plurality of horizontal sections disposed at both ends of the beams and columns, and a plurality of steel mesh structures wherein the beams and columns are tied together by a plurality of circular rebars and fastened by a plurality of steel mesh structures disposed above and below the beams and columns;
• wherein the bottom layer rebars of the foundation slab, the foundation steel columns, the upper layer rebars of the foundation slab, and the foundation rebars are assembled into a pre-assembled raft foundation.