坍塌

Pinyin: tān tā
Meaning：Go to rack and ruin
Sentence: 水坝坍塌了;它不够坚固，挡不住洪水。The dam gave way; it was not strong enough to hold the flood waters.

More:

坍：

Pinyin: tān
Meaning: Collapse; fall down
Radical: 土
Stokes: 7
Traditional: 坍
Common words/Phrase:
坍台 [tān tái] 【collapse】
坍方 [tān fāng] 【mountain creep】
坍陷 [tān xiàn] 【collapse】
坍岸 [tān àn] 【bank failure】

塌：

Pinyin: tā
Meaning: Collapse
Radical: 土
Stokes: 13
Traditional: 塌
Common words/Phrase:
塌陷 [tā xiàn] 【Cave in】
塌实 [tā shi] 【sureness】
塌台 [tā tái] 【collapse】
塌落 [tā luò] 【caving】
塌塌米 [tā tā mǐ] 【straw mattress】