In general each liquid compress the wall around it lateral pressure and concrete compress the surface of form with hydrostatic pressure.
A form anchor is used so that the form can resist enough against pressure. Form anchor are divided according to their usage.
buried form anchor used when concrete screen should be seal bar such as water budget or where the form anchor cannot be used for the second time.
repetitive form anchor in used when walls has no seal bar or section such as seal bar or sevtion such walls has holes in concrete because of technical problems.