Akademik

стоять столбом
СТОЯТЬ СТОЛБОМ <KAK СТОЛБ> coll
[VP; subj: human]
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to stand unmoving, usu. with a vacant look on one's face:
- X стоял столбом{{}} X stood motionless (stock-still);
- X stood there like a dummy (a statue);
- X stood as if rooted to the spot;
- [in limited contexts] X stood (there) gaping.

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.