Soil-displacement drill (1) for soil-displacing drilling in a surface (10) in order to form a foundation pile (2), comprising a drill pipe (3), a drill head (4) at an end of the drill pipe (3) with several flap leaves (5) which are pivotable between a closed position for closing off the end of the drill pipe (3) and an open position for making this end freely accessible and one or several closing elements (6) to keep these flap leaves (5) in their closed position and prevent pivoting of the flap leaves (5) which are configured to fail during drilling into the surface (10) in such a way that these closing elements (6) do not impede pivoting of the flap leaves (5). In addition, the present invention relates to an assembly of a drill head (4) and one or several closing elements (6) for such a soil-displacement drill (1), a method for soil-displacing drilling and a method for converting a soil-displacement drill (1) to form such a soil-displacement drill (1).