Study of Internal Force of Ring Tunnel in Stratum Skin Friction

Lining structure of round tunnel is looked as freely changing isotropic elastic circular ring in soil.Based on the elastic centre method of structural mechanics,considering main factors aflecting skin friction,the internal force formula of arbitrary section of round tunnel is deduced in the paper.From computation result of an example,it can be got that the affected trend of internal force of lining structure by skin friction is decreasing,especialy on the top and at the side of tunnel.At last,the authors suggest that the influence of skin friction should be consided in the calculation of internal force of lining structure in order to rationally allocate lining material in the design of round tunnel.