A process for producing a tunnel in stages comprises using face support elements (24), edge support elements (28), a supporting arch (18) and tunnel lining elements (10). The safety layer (31) comprises an inner section layer (32) which borders against the support elements (24), and an outer layer (33). The inner layer consists of a material which is less resistant to penetration of lining elements (20) than the outer layer (33). The lining elements are driven through the inner layer into the face (22). The inner layer preferably consists of e.g. expanded poly-styrol.
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