collapse, fall in, cave in, give, give way, break, founder(verb)

break down, literally or metaphorically

"The wall collapsed"; "The business collapsed"; "The dam broke"; "The roof collapsed"; "The wall gave in"; "The roof finally gave under the weight of the ice"

fall in(verb)

to take one's place in a military formation or line

"Troops fall in!"

join, fall in, get together(verb)

become part of; become a member of a group or organization

"He joined the Communist Party as a young man"

fall in(Verb)

To collapse inwards.

fall in(Verb)

Of a soldier, to get into position in a rank.