After putting madeline in the vault. ushers madness begins to increase. why dies he get so much worse?

Because all though he knows his sister is dead, he can still hear knocking and scratching sounds coming from her coffin. She's dead, but comes back to life to haunt him causing his madness to grow stronger. 

the use of “as” in the example to draw the resemblance. some more examples of common similes are given below. common examples of simile. our soldiers are as brave as lions. her cheeks are red like a rose. he is as funny as a monkey. the water well was as dry as a bone. he is as cunning as a fox. simile introduces vividness into what we say.