I can't go against what has been said.
But, being a PoCo/Utility worker myself, we bury our cables (400/230/11kV and 33kV) in PVC.
We've done it this way for over 30 years like that here and no worries so far.
I've worked with PVC Conduit up to 600mm(2ft) diameter and yes, it can be bent to an offset, if you are careful.
These days they use multiple little ones.
Oh well it was good for the experience I suppose. [Linked Image]
Just my own opinion, I'd never put metal in the ground, that carries live conductors.
In one word, Rust.