An improved model of deformation calculation for circular pressure tunnel with liner in strain-softening rock mass

By considering the interaction of liner and surrounding rock mass, without assuming the support pressure is known a priori, an improved model of solving plastic radius and the distribution of radial displacement around the circular pressured tunnel with liner is proposed. Based on Mohr-Coulomb yield criteria, the results obtained by the strain-softening model are compared with those of elastic perfectly plastic and elastic perfectly brittle models. The examples reveal that the difference of plastic radius obtained by the three models is comparatively smaller, but the differences of radial displacement and hoop stress are comparatively larger, which reveals that the selection of model is very important for predicting distribution of the radial displacement around tunnel. Without assuming the support pressure in advance and being able to consider more factors, the proposed model overcomes some defects of the previous studies and improves the approach of elasto-plastic analysis for tunnel.