Firstly- when's the last time you saw a turtle run? :-p
I think your question suggests that a turtle's shell is it's home. To me, a turtle's shell is like our skin, we don't really consider our skin to be our home.
Turtles [chelonians] usually have some sort of ecosystem they prefer. Whether it's a desert tortoise or a sea turtle, they live like most other animals in the Animal kingdom-
that is, they prefer a certain ecosystem. If that ecosystem is disrupted or becomes unihabitable they may "migrate" to a different area. [Exception being most types of sea turtles that have yearly migrations to lay eggs]