There are similar discussions on the forum. Please check and post updated questions if still unanswered.
Raft Edge or Corners Overstressed: https://www.sepakistan.com/topic/3106-raft-edges-and-corners-overstressed/?tab=comments#comment-10121
High Soil Bearing Pressure under Raft: https://www.sepakistan.com/topic/2918-high-soil-bearing-pressure-under-raft/?tab=comments#comment-9375
Calculating Soil Spring: https://www.sepakistan.com/topic/1303-spring-support-modulus-of-subgrade-reaction/?tab=comments#comment-3548
Numerous Questions on Raft Design: https://www.sepakistan.com/topic/1440-raft-design-for-a-2-basementg24-story-building/?hl=raft
Minimum Thickness of Foundation: https://www.sepakistan.com/topic/160-minimum-thickness-of-footing/?hl=raft