Abstract:

As a summary of the past research achievements, the paper analyses three criteria for the stability of surrounding rock of tunnels and puts forward that stability safety factor with strict mechanic basis can be taken as the quantitative criteria of the stability of surrounding rock. The paper states that the safety factor of surrounding rock has shear safety factor and tensile safety factor and suggests that the safety factor of strength reserve should be adopted as the safety factor of surrounding rock. New theory and new method of stability analysis of soil tunnel are established, and the load release of surrounding rock is taken into consideration in the calculation. The primary lining is seemed as elastoplastic material to reinforce the surrounding rock and the primary lining should have a certain safety factor to ensure the safety during tunnel construction. The secondary lining adopts elastic structure and ensures the safety of the tunnel in operation together with the combined action of surrounding rock and primary lining. The paper then provides a preliminary proposal for the classification of the surrounding rock and takes the safety factors without lining as the quantitative criteria of the selfsupport capability of surrounding rock of each grade. In this way, the parameters of mechanic strength of surrounding rock of each grade are obtained through inverse method, which can improve the rationality of the parameters. 

Key words: stability analysis, analytic criteria of stability of surrounding rock, FEM strength reduction, safety factor of shear, failure surface, soil tunnel, rock tunnel