劈
pī , pǐ · HSK 7
to split open
🪓⚡ 辟 (open up) over 刀 (knife) = a blade that splits things wide open
The 刀 knife radical sits at the bottom doing the chopping, while 辟 on top carries the pī sound. Same verb covers an axe splitting wood and lightning splitting the sky.
劈 — knife 刀 + phonetic 辟
A semantic-phonetic compound: 刀 (knife) gives the meaning of cutting or splitting, while 辟 supplies the sound. The original sense was to split or cleave with a blade, as in chopping wood, and it later extended to splitting open or cracking generally.