A sealed, thermally insulated tank incorporated into a support structure for containing a fluid, in which a tank wall comprises, from the outside of the tank toward the inside of the tank: a load-bearing wall, a thermal insulation barrier (2, 4) retained on the load-bearing wall, the thermal insulation barrier being formed from a plurality of insulating elements (15, 30) juxtaposed to form a support surface, and a sealing barrier (3, 5) bearing on the support surface, an insulating element having a generally flattened prismatic shape, and comprising: a thermal insulating material, a plurality of load-bearing elements passing through the thermal insulating material along a direction of thickness perpendicular to the tank wall, and a cover panel (11, 34) and a base panel (16, 31) parallel to the tank wall and arranged at the first ends and the second ends, respectively, of the load-bearing elements of the insulating element, so as form exterior walls of the insulating element, the first ends of the load-bearing elements being fastened to the cover panel and the second ends of the load-bearing elements being fastened to the base panel, and characterized in that the insulating element further comprises an anti-buckling plate, parallel to the cover panel (11, 34) and to the base panel, sandwiched between a first (21 a) and a second (21 b) portion of the thickness of said thermal insulating material, the anti-buckling plate having a plurality of load-bearing elements passing through it in a plurality of openings in the anti-buckling plate, the openings being spaced apart from one another so as to provide a distance between two neighboring load-bearing elements, in a plane defined by the anti-buckling plate. a load-bearing wall, a thermal insulation barrier (2, 4) retained on the load-bearing wall, the thermal insulation barrier being formed from a plurality of insulating elements (15, 30) juxtaposed to form a support surface, and a sealing barrier (3, 5) bearing on the support surface, an insulating element having a generally flattened prismatic shape, and comprising: a thermal insulating material, a plurality of load-bearing elements passing through the thermal insulating material along a direction of thickness perpendicular to the tank wall, and a cover panel (11, 34) and a base panel (16, 31) parallel to the tank wall and arranged at the first ends and the second ends, respectively, of the load-bearing elements of the insulating element, so as form exterior walls of the insulating element, the first ends of the load-bearing elements being fastened to the cover panel and the second ends of the load-bearing elements being fastened to the base panel, and characterized in that the insulating element further comprises an anti-buckling plate, parallel to the cover panel (11, 34) and to the base panel, sandwiched between a first (21 a) and a second (21 b) portion of the thickness of said thermal insulating material, the anti-buckling plate having a plurality of load-bearing elements passing through it in a plurality of openings in the anti-buckling plate, the openings being spaced apart from one another so as to provide a distance between two neighboring load-bearing elements, in a plane defined by the anti-buckling plate. a thermal insulating material, a plurality of load-bearing elements passing through the thermal insulating material along a direction of thickness perpendicular to the tank wall, and a cover panel (11, 34) and a base panel (16, 31) parallel to the tank wall and arranged at the first ends and the second ends, respectively, of the load-bearing elements of the insulating element, so as form exterior walls of the insulating element, the first ends of the load-bearing elements being fastened to the cover panel and the second ends of the load-bearing elements being fastened to the base panel, and characterized in that the insulating element further comprises an anti-buckling plate, parallel to the cover panel (11, 34) and to the base panel, sandwiched between a first (21 a) and a second (21 b) portion of the thickness of said thermal insulating material, the anti-buckling plate having a plurality of load-bearing elements passing through it in a plurality of openings in the anti-buckling plate, the openings being spaced apart from one another so as to provide a distance between two neighboring load-bearing elements, in a plane defined by the anti-buckling plate.