土崩瓦解 tǔbēng-wǎjiě
[crumble;disintegrate;collapse like a house of cards;fall apart;fall to pieces;go to hell in a hack] 如土之崩坠、瓦之破碎。比喻彻底崩溃、不可收拾
封建帝制不是早就土崩瓦解了吗