although it depends on the geographical regions and country regulations. However, are there any regulations for a minimim safe distance from the shore line? please share your information with any research paper or policy document.
I'm not sure I understood the question. In any case, the answer, in my view, has more to do with engineering judgment than regulation.
Onshore windmills need to be far enough inland to remain unaffected by high tides and waves that might affect the foundations.
Offshore windmills need to be far enough out to sea to be constructable using marine construction equipment (crane barges, pile drivers, transport barge, tugboats) but not so far out to sea that they interfere with navigation.
These are just some of the questions that come to mind when thinking about windmill site selection. Other questions that relate to both onshore and offshore sites would have to do, for example with bird migrations. You don't want windmills in the bath of migrating birds.
Infact various concrete codes recommend the grade of concrete in various environmental exposure. These codes also recommend the concrete cover required on the basis of severity of exposure of concrete.