pin (someone or something) beneath (someone or something)
To restrain or immobilize someone or something beneath someone or something else. Often used in passive constructions. The earthquake pinned me beneath a fallen beam. He was pinned beneath the giant wrestler. I pinned the trap beneath a hefty boulder to keep it from being blown away.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
pin someone or something beneath (someone, something or an animal)
to trap someone or something beneath someone, an animal, or something. The mine cave-in pinned four miners beneath a beam. I held the alligator's mouth closed and pinned it beneath me.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.