Major road closed for repairs after lorry fire
The incident happened just before 02:00 BST on the northbound carriageway but both sides of the road were damaged, National Highways said.
Thames Valley Police said the driver of the lorry sustained minor injuries and nobody else was hurt.
Drivers travelling southbound should follow the diversion from Botley interchange to the A34 Milton interchange mainly using the A420 and A338 west of the A34.
Drivers heading north should follow the diversion in place from Hinksey Hill interchange to the A34 Peartree interchange, mainly using the A40 and A44 east and north of the city centre via the southern and eastern bypasses.
Oxfordshire Fire and Rescue Service has advised people to avoid the area.
National Highways said the closure was expected to remain in place until at least 18:00 BST.