How does the “heavy slab” fall in Great Expectations?
The heavy slab in the story falls when the sultan cuts the rope.
Pip uses the metaphor of the heavy slab to demonstrate that he has entirely lost his life to Estella. He is completely in love with her, and he has no control over what happens to him. In other words, he is lost to his heart.
All being made ready with much labor, and the hour come, the sultan was aroused in the dead of the night, and the sharpened axe that was to sever the rope from the great iron ring was put into his hand, and he struck with it, and the rope parted and rushed away, and the ceiling fell. (Ch. 38)
The story that Pip is referring to is Tales of the Genii, which is also about a man who lost his head over a woman. Pip comments that both he and Estella have been affected by Miss Havisham. She has influenced both of their abilities to love.
So, in my case; all the work, near and afar, that tended to the end, had been accomplished; and in an instant the blow was struck, and the roof of my stronghold dropped upon me. (Ch. 38)
Pip has known Estella since he was young and impressionable. He fell in love with her when they were both children. When he says that the roof came down on him, he is speaking metaphorically. He is saying that he is completely and hopelessly in love.
Miss Havisham did not just destroy Estella's life with her games. She created in Estella a weapon to use against men, and she used Pip as a training device. The end result was successful in that Pip fell in love with Estella, and Estella was incapable of falling in love with anyone. Both of them were tied together for life.