Using monitoring data to analyze and evaluate internal force of supporting structure is an important problem in dynamic design and construction of tunnel

which has great significance for construction safety. According to the characteristics of shotcrete layer in initial support and the theory of circular beam on elastic foundation

based on touch stresses between shotcrete layer and surrounding rock

the analytical solution of internal force is deduced. The stress concentration position is obtained

which is convenient to make relative safety countermeasures in the following construction. The analysis of tunnel project excavated by bench method shows that the analytical expression of solving internal force based on touch stresses is a new and effective way

so as to provide a more reliable basis for the safety assessment of tunnel structures.