The document describes different types of raft foundations - flat plate, plate thickened under columns, waffle slab, plate with pedestals, and basement walls as part of the plate. It explains that all of these types involve laying a simple slab and casting columns. It then provides an example of a building with a raft foundation that began to float due to increased water pressure below, and how a puncture at the bottom of the raft helped the structure sink back down.

1. RAFT
FOUNDATION

2. COLUMN
RAFT/SLAB

5. A) FLAT PLATE
• IN THIS TYPE OF FOOTING A SIMPLE PLAIN SLAB
IS LAID AND COLUMNS ARE CASTED
• THIS IS THE SIMPLEST TYPE OF RAFT FOOTING

6. B) PLATE THICKENED UNDER COLUMN
• IN THIS TYPE OF FOOTING A SIMPLE PLAIN SLAB
IS LAID AND COLUMNS ARE CASTED
• THIS IS THE SIMPLEST TYPE OF RAFT FOOTING

7. C) WAFFLE SLAB
• IN THIS TYPE OF FOOTING A SIMPLE PLAIN SLAB
IS LAID AND COLUMNS ARE CASTED
• THIS IS THE SIMPLEST TYPE OF RAFT FOOTING

8. D) PLATE WITH PEDESTIAL
• IN THIS TYPE OF FOOTING A SIMPLE PLAIN SLAB
IS LAID AND COLUMNS ARE CASTED
• THIS IS THE SIMPLEST TYPE OF RAFT FOOTING

9. E) BASEMENT WALLS AS PART OF THE
PLATE
• IN THIS TYPE OF FOOTING A SIMPLE PLAIN SLAB
IS LAID AND COLUMNS ARE CASTED
• THIS IS THE SIMPLEST TYPE OF RAFT FOOTING

12. • THE FOLLOWING BUILDING HAD A RAFT
FOUNDATION.
• THE INCREASE IN WATER PRESSURE BELOW
THE RAFT MADE THE RAFT TO FLOAT ON
WATER.
• TO SUNK THE FOUNDATION BELOW, A
PUNCTURE WAS MADE AT THE BOTTOM
LEVEL OF THE RAFT WHICH HELPED THE
STRUCTURE TO SINK DOWN.