ÖNORM EN 815

1.1 Field of application This standard is applicable to unshielded tunnel boring machines, IBMs, and rodless shaft boring machines, SBMs, and their towed or attached back-up equipment for driving tunnels or shafts in rock where the whole area is excavated in one or more steps by mechanical means. It specifies essential safety requirements for the design, construction and maintenance of such machines when used in non-explosive atmosphere together with the methods of verification. The standard specifies monitoring for hazardous atmosphere. For TBMs and SBMs which are to be used continuously in explosive atmosphere, additional relevant standards also apply. This European Standard deals with all significant hazards pertinent to unshielded tunnel boring machines and rodless shaft boring machines for rock, when they are used as intended and under the conditions foreseen by the manufacturer (see clause 4). This European Standard specifies the appropriate technical measures to eliminate or reduce risks arising from the significant hazards. 1.2 Description of the machines The general term "unshielded tunnel boring machines" encompasses various kinds of machines for mechanical excavation of underground openings such as tunnels and inclined shafts. This is done in a continuous process, without blasting, using a rotating cutter head. Depending on the hardness of the material being excavated, tools of different types are used to cut the rock. Normally, rolling discs are employed in medium to very hard rock. AH tunnel boring machines, TBMs, and rodless shaft boring machines, SBMs, have the tools mounted on a cutter head which rotates under thrust against the rock. The torque required to rotate the cutter head is developed by electric or hydraulic motors and the thrust is normally delivered by hydraulically powered cylinders. The torque and thrust reactions created by a TBM or SBM have to be resisted by anchoring the complete machine inside the bore itself by means of a gripping system which is reset after each boring stroke and allows the machine to be steered in the desired direction. TBM s normally operate in a near to horizontal direction but can also be used to drive inclined tunnels. When the incline becomes too steep, a second anchoring system will be provided to prevent the machine from sliding down while the primary grippers are reset. In most cases TBMs work the full face of the tunnel. However, in some cases the tunnel is driven in two or more phases, by starting with a pilot hole which is enlarged in one or more steps. This method is called reaming. The machines used are in principle the same as a TBM driving the whole tunnel area in one step. SBM s resemble closely TBMs but operate in vertical direction. The shaft is in many cases sunk in a multistage operation, that is (i.e.), first a pilot hole is bored using a raise bore machine and the pilot hole is reamed by using the SBM. Normally for this method, the shaft bottom is already undercut to provide adequate room for the muck and its removal. The full face of the shaft can also be bored in one step. In this case the muck is transported to the top of the shaft. TBMs and SBMs intended for work in unstable rock are provided with equipment for the erection and handling of rock reinforcement and/or lining. The specified requirements of this standard conform