Analytical solutions for collapse mechanisms in tunnels with arbitrary cross sections

While innovative processes take continuously place in tunneling, which remains a rapidly evolving technology, the reliable prediction of impending collapse of roofs appears still one of the most difficult tasks in civil engineering. On the basis of a theoretical approach recently proposed by the present authors, a comprehensive analytical solution for collapse mechanisms in tunnels with arbitrary excavation profiles in plastic Hoek–Brown rock masses is presented and discussed. Special attention is given to examples concerning circular tunnels and the results allow some interesting considerations on the mechanics of collapse.