Analysis of the damages affecting the pre-casted concrete liner of a deep tunnel

The origin of the fractures that developed in the pre-casted concrete liner of a deep tunnel is investigated through a series of non-linear finite element analyses in plane strain regime. Three possible causes are considered, i.e. the excessive mountain pres-sure, the anisotropic in situ stress field and the incomplete filling of the rock/lining gap. The calculations are based on two numerical models, one of which accounts for the strain softening behaviour of the lining and for the rock/lining mono-lateral con-tact. The results of analyses show that the observed damages are likely to depend on the mentioned incomplete filling. On this base some conclusions are drawn on the possible procedures for the structural restoration of the opening.