| Lining split of tunnel structure should be eliminated during construction phase and is the point prevention of the maintenance management in operating stage. More than50tunnels are inspected and numerous cases of lining cracks are statistical analyzed in this paper. The generating mechanism of lining cracks and the mechanical characteristics of the tunnel structure under main influencing factors are studied by XFEM based on concrete fracture mechanics theory. A safety assessment method is introduced to assess tunnel lining with crack disease. The main results are as follow:(1)The major style and hazards of lining is analyzed. Taking the inspection for tunnels as background, the content and method of field inspection are introduced. Further, the distribution law and inducements of crack are obtained by field survey and statistics of50highway tunnel.(2)The basic theory of fracture mechanics and extended finite element method (XFEM) is introduced. Further simulation of the experiment on lining structure is performed with XFEM. By comparing the test results with simulation outcomes, the feasibility of XFEM in analyzing the lining crack is discussed.(3)Finite element models of lining with inclined press load, cavity and relaxation pressure are established to study the initiation mechanism of crack in lining, appearances of cracks, propagation law and the influence of the bearing capacity of lining.(4)For tunnels in operation, comparisons are made between the linings with distinct degrees of damage. Based on which the influence law of bearing capacity and deformation ability is obtained. Finally, associated with related references, this paper proposed a classifying and safety assessment method for tunnels lining with crack disease. |
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