step on
蹂 centers on the act of stepping on or trampling something underfoot, often with a sense of forceful or repeated pressure.
蹂 combines 足 (foot) with 柔, which likely contributes the sound and may suggest a soft or yielding surface being pressed down. The exact historical development is uncertain.
The foot radical 足 steps on something soft and pliable like 柔 (soft, gentle), trampling it down.
For ジュウ, imagine stepping on a piece of juicy fruit: the juice squishes out underfoot, and 'juice' cues ジュウ.