You really can not bury J-boxes or conduit bodys ("T"s)
314.29 Boxes and Conduit Bodies to Be Accessible.
Boxes and conduit bodies shall be installed so that the wiring contained in them can be rendered accessible without removing any part of the building or, in underground circuits, without excavating sidewalks, paving, earth, or other substance that is to be used to establish the finished grade.
Exception: Listed boxes shall be permitted where covered by gravel, light aggregate, or noncohesive granulated soil if their location is effectively identified and accessible for excavation.
The exception gives you a little leeway , but the box will have to be listed for direct burial.
