Time Dependent Ground Loosening Effect on Polilith Rock Mass Conditions in Shallow Tunnels

The time dependent rock mass behaviour, known as the stressdisplacement- time relationship, and tunnel stability depend fairly on the technical conditions of the rock mass which are taken into consideration as continuum, discontinuum or quasi-continuum surroundings. Accurate definition of rock mass and understanding of rock mass behaviour are the fundament of engineering design. However, it is a fact that an exact simulation of system seniority is almost impossible especially in polilith rock mass conditions. In this paper, the application of ground loosening effect into numerical analysis has been studied. The core support method, the lining reduction method and the stress reduction method have been applied on a shallow urban tunnel. As an alternative, Vardar time dependent in-situ rock mass method is applied to the case study, as well. The results have been compared with measured in-situ tunnel displacements. It has been seen that, Vardar method is an effective method to define the polilith rock mass in discontinuum mechanics.