Two men who came to Australia on humanitarian protection visas have been jailed for the "vicious and cowardly" gang rape of a homeless woman sleeping under a Melbourne bridge.

Thwang Za Lian, 22, and Kapling Hlawnceu, 21, found the woman under a Werribee footbridge before they held her down, covered her mouth and raped her one night in August 2017.

The pair had dreamt of new lives after escaping poverty and persecution in their native Myanmar by fleeing to Malaysia and coming to Australia as refugees several years ago.

Instead, they devastated the life of someone else - a 36-year-old woman

who was sleeping rough under Werribee's Bicentennial Bridge.

For more than 20 minutes the woman was allegedly confronted by three men, forced to the

ground and raped with her face covered.