The invention relates to a bulkhead (30) formed of a number of metal tongue-and-groove elements (1a, 1b, 1c) into soil (M), the tongue-and-groove elements comprising a tubular tongue (3) closed at the lower end by a tip element (11), and a tubular groove (2) with a longitudinal slot (8) provided in the housing, and a web (4) connecting the tongues-and-grooves. The tongues include at their lower ends pile shoes (5) consisting of a tip element (10) and a collar (12), the maximum diameter (D1) of which is larger than the outer diameter (D2) of the tongue and at least equal to the distance (W2) of the central line of the tongue and the outer surface of the groove, and flow apertures (17) for mortar (B). The flow apertures open from the interior (13) of the tongue above the collar. In the bulkhead, the interior of the tongue and the space between the tongue and the groove are filled with mortar, and possibly, the grooves are covered by a mortar layer. The invention also relates to a method for forming a bulkhead sealed with mortar and the tongue-and-groove element for the bulkhead.