Development of urban areas and the expansion of cities and the need of these communities for infrastructure facilities such as urban transportation tunnels, water tunnels, etc. the need to build underground structures in these areas has increased. One of the methods of tunnel excavation is using Tunnel boring machine (TBM). In order to deal with ground displacement, maintain the stability of the excavated space, prevent groundwater from entering the tunnel and other executive issues such as accelerating the progress of the project, excavation is done simultaneously with the installation of concrete segments. Due to the difference in excavation diameter with the outer diameter of prefabricated concrete parts, it is necessary to fill the annular space between the segment and the excavated tunnel immediately with suitable materials to prevent future problems such as subsidence or water leakage into the tunnel. The filler is usually pumped into the back of the segment in the form of grout. Grout is a mixture of materials such as cement, sand, bentonite, water and other materials, each of which is added to the grout in a certain proportion. A suitable grout will be a grout that meets all the executive, technical and economical requirements well. Another possible factor influencing the design of the grout behind the segment is the amount of tunnel deformation during the grout setting. Therefore, in this study, by conducting laboratory tests on grout and host soil of Isfahan Metro Line 2 and three-dimensional numerical simulation, the time dependent behavior of the surrounding soil was eva‎luated using the Burger model and grout strength changes over a four-day period were investigated. Then, according to the executive considerations of Isfahan Metro Line 2 and the tunnel excavation sequence, using the burger creep model, the effect of grout setting time on tunnel displacement was eva‎luated. The results of the analysis showed that most of the tunnel displacements occur after one day of tunnel excavation, so reducing the grout setting time from four days to one day cannot have a significant effect on reducing tunnel displacements and surface subsidence. The amount of grout resistance as one of the design parameters does not have a significant effect on the surface subsidence. Therefore, it is not one of the controlling parameters in grout design. Items such as ease of pumping, minimum amount of bleeding, shrinkage and filtration, no clogging of the pipe during the shifts changing and economic considerations in the composition of the grout are some of the basic controlling parameters in the design of the grout behind the segment.

سعيد مهدوي

داوود مستوفي نژاد

لهراسب فرامرزي، محمدرضا افتخار