عنوان مقاله [English]
نویسنده [English]چکیده [English]
One of the most important characteristics of Excavation Damaged Zone in stability analysis methods is the effect of body forces due to the weight of the damaged rock mass. The main purpose of this research is calculation of the body forces effect on the induced stresses and consequently the displacements surrounding circular tunnels and determination of support pressure. Therefore, a new analytical solution for calculating the ground reaction curve at the tunnel crown around a circular tunnel, considering Mohr-Coulomb failure criterion and non-associated flow rule, is developed. Validation was carried out based on two case studies. The obtained results showed that the trends of induced stresses at the sidewall and tunnel crown are not the same. In other words, due to these differences, the shape of Excavation Damaged Zone in hydrostatic stress field is a noncircular shape. Moreover, based on the new solution, a comparison between ground reaction curve at tunnel crown and sidewall was carried out and two new achievements “minimum required support pressure” and “maximum allowable strain” were presented. Also, based on the obtained results, it was observed that with decreasing the dilation angle, the maximum allowable strain is decreased too and consequently, the support system must be installed quickly.