An upward force is thereafter exerted on the column, notably by deballasting the same, thus causing the resilient element 6 to move into abutment against the flange 33 of the abutment means 25, a portion of the external edge 13 of element 6 having moved past the flange 33 of the abutment means 25 owing to the radial contraction caused by the inflation of the annular cavity 12.