Numerical modeling of cracking of tunnel lining by combined finite-discrete element method

By using the combined finite-discrete element method (FDEM) and comparing with the laboratory test results of prototype concrete lining segment in Japan, it is obviously found that the initial cracks, crack propagation and collapse of the concrete segment of tunnel are in good agreement with the results of numerical model. Then, by establishing the model for load structure, three dominant pressures including local bias pressure, local void behind lining (pressure free), and loose pressure on crown are respectively taken into account to investigate the process of cracking and the distribution of cracks under their different positions, ranges and magnitudes imposed on the concrete lining. This study may provide valuable insight for understanding the process of cracking in concrete lining of tunnel by means of continuous-discontinuous methods to evaluate the stability and sustainability of tunneling structures. It also lays the foundation for the crack prevention and reinforcement of tunnel lining.