Abstract:

Crack factor (CF) is proposed on basis of Griffith criterion to analyze the safety of the lining of the smallspaced intersecting tunnel constructed by benchcut method, as well as the safety of the lining of the existing tunnel. It is supposed that crack will occur to the lining when CF is more than 1 and that the lining is safe when CF is less than 1. The safety of the tunnel lining is analyzed, on basis of the crack factor and the safety coefficient of the lining provided in relevant standards, by means of ANSYS. Conclusions drawn are as follows: during the process of the construction of the new tunnel, the circumferential safety factor of the lining of the underconstruction tunnel at the intersection point is less than the longitudinal safety factor, but they both meet the requirements of relevant standards; the crack factor of the lining of the existing tunnel is far less than 1, and the cloud picture of the crack factor is symmetrical along the axis of the underconstruction tunnel. 

Key words: intersecting tunnel, smallspaced, bench method, crack factor CF, Griffith criterion, ANSYS