Wow.
I am sorry you have to go through this.
Do you have a camera you could hide and videotape one of her drunken rages? If so please do this and make a couple of copies of the tape. Show her one when she is sober. This has worked with people in the past, and they (at least some of them) will get help.
With the other copy, give one to your Grandmother or a good friend you can trust. You may need this in front of a judge someday if you want to be legally emancipated from your mother.
Let us know how things go.
Whatever you do, never forget how alcohol has done this to your mother, and don't ever get into alcohol and drugs.