Abstract: With a ring seal for apertures of multi-shell structures, especially of underground operations, by which a tubular sealing element after insertion into the ring aperture between shells of the structure and after introduction of a filler material into the sealing element with the required sealing pressure, which is applied to the bordering shell surfaces of the aperture, is provided, according to the invention, that the sealing element, consisting of at least one tubing with ends inserted into each other, upon insertion into the aperture with the excess of its periphery provided opposite the periphery of the aperture and through the shortening of the overlap of its ends in the aperture as well as the stretching of the sealing element is applied axially and radially.