Abstract: To investigate the mechanical behaviors of tunnel surrounding rock in permeable rock stratum, an analytical model of stress and displacement of permeable deep buried circular pressure tunnel based on displacement release coefficient is established using the complex function method combined with Biot′s poroelastic theory. Based on the stressstrain constitutive equation and planestrain compatibility equation, the nonhomogeneous biharmonic equation of stress function is derived. Then, the stress function is expressed by complex potential function, and the coefficients of complex potential function are determined according to the boundary condition at the inner surface of liner and rock/liner interface. An example is calculated according to the given parameters, and the calculation results are compared with those of commercial finite element software, which shows excellent agreements. Meanwhile, by selecting different tunnel parameters and farfield stress ratio for sensitivity analysis, it is found that the tunnel has great differences in mechanical behavior under the conditions of soft liner and hard liner. The displacement release coefficient has a significant impact on the hoop stress and radial stress in the surrounding rock. The increase of displacement release may lead to tensile stress in the rock.

Key words: deep circular pressure tunnel, displacement release coefficient, poroelasticity theory, complex function method, analytical model