Method of lining tunneled tubes

Claim 1

In a method of forming a tunnel wherein a subterranean tube is excavated, concrete is applied to the wall of said tube as a load-bearing structure, the improvement wherein: (a) a concrete mix of cement, aggregate and water forming a concrete of the concrete group B II of German Industrial Standard DIN 1045 is formed at a location remote from the tunnel excavation by mixing with the cement, aggregate and water a steel-pin additive in an amount of about 100 kg/m 3 , the steel-pin additive consisting essentially of steel wire sections having lengths of 35 to 50 mm and thicknesses of 0.8 to 1.2 mm so as to uniformly disperse said steel wire sections in the resulting concrete mix, said mix forming a concrete of strength class Bn 350; (b) pumping said mix without agglomeration of said steel wire sections and separation thereof from the remainder of said mix to the excavation and introducing said mix between said wall and a form work juxtaposed therewith; and (c) hardening said mix against said wall without agglomeration or separation of said sections into a load-bearing structure.