Sharif Digital Repository

Ground squeezing is defined as time-dependent shear displacement of rock mass that causes the decrease of the calculated excavation area of tunnels.Ground squeezing is one of the phenomenons that causes serious problems including the collapse of tunnels’ walls and TBM jamming during the construction of tunnels. Hence, the assessment of ground squeezing is an essential issue in tunneling. In this thesis, different ground squeezing potential prediction methods will be assessed. These methods consist of empirical, semi-emperical, analytical, and numerical methods. After assessing the ground squeezing potential, if it is evaluated high for a project, it will be required to consider the... 

One of the most important conditions in weak rock masses with high overbuerden which causes problems in the tunnel construction, is squeezing condition. This is actually defined as increases in the shear deformation of the rock element, when the element is under constant deviatoric stress. Qomroud water tunnel with a length of 36 km and a drilling diameter of 4.5 meters deliveres water from the branches of the Dose to the Golpaygan and Qom. Because of a high overbuerden and existence of schist, slate, clay limestone zones, studing of squeezing potential,prediction of convergence of tunnel wall and lining pressure in this tunnel is very important.In this research, we stuied the 25th to 35th... 

In this research with Finite Element Methods in ABAQUS, numerical modeling has done in three-dimensions, which can be used to determine the effect of different factors on the surface settlement. Also, various factors such as geotechnical conditions, tunnel diameter,tunnel depth, the impact of the thickness of the segments and the amount of eccentricity of the structure relative to the longitudinal axis of the tunnel considered in this study. Face Pressure Supports, and Grout Injection Pressures are taken into account, too.Tunnel drilling causes a change in the displacement area and creates a changing zone around the tunnel. In this regard, not only adjacent buildings will be affected by... 

In this research with Finite Element Method in ABAQUS, a Number of Numerical modeling has done in two-dimensions, which can be used to determic the effect of different factors on the seismic vulnerability of tunnels. Also, varios factor such as Geotechnical conditions, tunnel depth, tunnel thickness and ground water is considered in this study.One of the parameters considered in designing tunnels is the ability of the tunnel’s lining to withstand the seismic and geotechnical loads. Each section of the tunnels are designed according to the maximum stress witch created due to the earthquake. this stress’s created in tunnels can be devided in to 3 category : the axial force,the Shear force and... 

In this study, the interaction of tunneling of line 2 of Mashhad metro and existing metro station (Shariati station) in line 1 has been investigated. To produce the stress and displacement which is caused by excavation of station, the process of station excavation has been modeled by method of cut and cover.This method is the common method for station construction at Shallow depth and is used in several cases in line 1 of Mashhad metro. The piled-raft system is used in foundation of central part of the station to reduce the settlements and the effects of interactions between the station and new tunnel. The new tunnel under the station is surrounded by two rows of lateral piles with distance... 

Excavation of metro tunnel beneath groundwater level causes disturbance of hydro geological balance and change in stress conditions at its environment. One of the usual methods of the tunnel construction is utilizing tunnel boring machine and one of the most important of them is called TBM-EPB which takes advantage of the earth pressure balance method. Control of surface settlements which is a result of creating underground space in urban area is a matter of great importance and is influenced by various parameters. This thesis has tried to investigate factors such as geotechnical properties among cohesion, internal friction angle, elasticity modulus, permeability and porosity and also...