What does destructive mean? If you are destructive, you destroy something.
So, a destructive force is an event that breaks objects into smaller objects or pieces.
Look at the picture below. Do you see examples of the effects of a destructive force?
http://www.thetruckersreport.com/truckingindustryforum/road-stories/68681-trucking-can-be-like-bad-marriage-67.html