Tubular element for tunnel construction

A hollow tube element of a predetermined maximal width and defining a predetermined axis, adapted to be secured to an adjoining hollow tube element for use as building blocks for the construction of a tunnel passage, and being rotatable about its axis through an arbitrary angle relative to the adjoining tube element, for preselecting a spatial tunnel path,

• comprising in combination:
• a plurality of interconnected slabs, each slab differing dimensionally from at least some other slabs, said slabs including first and second groups, each slab having two peripheral end surfaces forming an acute angle with one another, and two axial end surfaces disposed opposite one another, the peripheral end surfaces of said first and second groups of slabs converging in respective opposite directions to first and second lines of intersection, the axial end surfaces of each slab of each tunnel element being disposed in two respective planes which converge to a third line of intersection,
• first and second predetermined conicities with respect to a radial direction of a corresponding slab of said first and second groups, respectively, being defined by respective imaginary first and second cones,
• each conicity having a cone axis passing through said predetermined axis, and having a circumferential surface portion inscribed between the two peripheral end surfaces, and one of said axial end surfaces of a corresponding slab,
• whereby only a limited and relatively small even number of slabs of different respective dimensions are required to form a plurality of respective tube elements so as to construct said tunnel passage from said tube elements.