Computation And Analysis Of Reinforced Concrete Lining Of Tunnel In Rock

As to the R.C. lining in rock, the enclosure rock and lining are always regarded as linear elastic material in the existing design methods, then, the reinforcements needed and the maximum crack width are calculated as the code suggests which does not consider the nonlinear properties of the material. It is unreasonable to do so. This paper adds a computing module ,which includes the elasto-plastic constitutive relationship of the rock , internal force calculation and arrangement of reinforcement, to the existing R.C. nonlinear finite element program, forming a calculating and design program in which the cooperative action between rock and lining is taken into account.On the bais of validating the program sufficiently, this paper studies the internal force and arrangement of reinforcement of R.C. lining for the circular and gate-hole tunnel in rock. The following conclusions are achieved: Firstly, the result gained with the present method, in which the shear restriction between the enclosure rock and the lining is not considered, is different from the actual value. The moments and axial force of the flat part are larger ,and the axial force of the curved part is smaller. Secondly, whether the internal force of lining reduces when it is computed as nonlinear material, compared with the linear elastic material, depends on the fact that whether the crack appears. Thirdly, when the lining is computed with F.E.M, the amount of steel and maximum crack width are less than the results gained by the code method. Fourthly, the lining is more difficult to get in touch with the enclosure rock when the diameter of the tunnel become smaller, and the thickness of lining becomes larger.In addition, in this paper the PengShui tunnel is analysed with the program, and it points out that the elastic module of the enclosure rock has great affect on the internal force and arrangement of reinforcements of lining.