Abstract：
Controlling soft surrounding rock deformation has been a challenge in tunneling, but pre-lining support has significant advantages in this situation. By means of a load-structure model, ANSYS calculations and analysis show that the buried depth has a decisive influence on the safety factor of the pre-lining. To obtain reasonable parameters of pre-lining, the safety factor of pre-linings with different thicknesses, different steel arch spacings, and different concrete strengths are analyzed under the condition of a 30 m buried depth. The results show that (1) thickening the pre-lining can effectively increase its safety factor; (2) for a pre-lining of 30~40 cm thick, the effect of steel arches on the safety factor is significant, while for a 40~50 cm thick pre-lining, the effect of steel arches on the safety factor is less; (3) the effect of early concrete strength on the safety factor of the pre-lining is rather significant, therefore, the early strength concrete shall be used to achieve a higher safety factor; and (4) the load of the surrounding rock in conventional tunnel design methods is not applicable for the pre-lining method and the loading mechanism of surrounding rock in the pre-lining method is pending for further study.
2013, Vol. 50 