Sharif Digital Repository

As the crowded cities require public transportation and because of lack of space on the ground, Subway and boring underground tunnels encountered. In this thesis the interaction of boring the line 7 of Tehran metro with the existing station of line 1 of Tehran metro (Molavi station) is studied. By changing the soil specification, The surface settlement is significant so the soil specification is one of the important parameters of the interaction. For comparinf the effect of these parameters, the soil settlement and bending moments is investigated in different parts of station while the lower tunnel is passing beneath it. The 3D Abaqus software is used for modeling this interaction. In... 

Recently, Needs for construction of rock structures and underground ones such as tunnels, dam foundations, power plants and caverns built to keep oil, gas and nuclear waste has increased dramatically. In order to design, construct and excavate these underground structures safely and economically, full understanding of rock mass properties, suitable tools and practical techniques of drilling are necessary. Because of existing this discontinuities, including joints and layered rock masses and their effects on mechanical behavior of rock mass, it is necessary for the geomechanical profile, shear strength and failure mechanism of rock mass to be accurately indentified. Shear strength criterions... 

Influence of excavating the Tehran metro line 7 tunnel on surface settlement, stresses and deformations induced in Towhid tunnel is investigated using numerical modeling. Construction of Metro tunnel as the new one must be carried out without imposing any damage to the Towhid tunnel as the existing tunnel. Towhid tunnel is a set of twin tunnels along the Chamran highway in Tehran. The tunnels were constructed using sequential excavation method and lined with cast in place reinforced concrete; on the other side metro line 7 is being constructed using 2 EPB tunnel boring machines and lined with reinforced concrete segments. This research consists of the study of the effects of pillar width,... 

It is important to provide an appropriate and economically method with technical and engineering considerations to stabilize excavated underground spaces. The necessity of this, especially for the construction of underground metro stations located in the cities which faces many problems, is more evident. In this research, it has been tried to introduce an optimal method according to the type of area for the construction of the underground station. In order to obtain stress and strain condition in structural elements and surface deformations due to different stages of excavating, numerical modeling in FLAC3D has been used. By examining the parameters that affect the sustainability of this... 

Dynamic design of underground structures is complicated and difficult. Although underground structures are less vulnerable than surface structures, dynamic analysis of these structures during their design process is necessary. In this project, numerical studying of fault effect on underground structures and its dynamic responses, focusing on tunnel Shebli was conducted. Two-dimensional model utilizing UDEC software which is based on descrete elements method was used for this analysis. Time history of Manjil Earthquake using horizontal component of ground acceleration which is propagated toward earth surface was applied to models as a shear wave with respect to depth and type of rock. To... 

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... 

Public transit system has become one of the targets of terrorist attacks using explosives, examples of which include the 1995 attack on Paris subway and the 2004 attack on Moscow subway. Under the present context of intense threats of terrorist attacks on subway systems in metropolitan areas around the world, explicit three-dimensional Finite Element method was used to investigate the dynamic response and damage of subway structures under internal blast loading. The study was motivated by the fact that explosion in subway structure may not only cause direct life loss, but also damage the subway structure and lead to further loss of lives and properties. The study used the Mashhadsubway... 

The need to build underground structures like tunnels, oil reservoirs are increasing and it requires a good knowledge of behavior of mass rock, exact data and parameters for safe and economic design. Filling materials which usually transfer with water into the joints reduce shear strength of joints significantly and change the behavior of the joints. To evaluate shear behavior of filled joints, 24 tests were conducted with large scale direct shear test apparatus on model rock joints with a regular “saw tooth” surface profile with the dimensions of 15cmx15cmx18cm. Filled material had specified specifications like particles size and strength parameters.
Infill thickness, moisture content... 

Three dimensional analyses have been carried out for predicting the behavior of the jointed rock slope of the abutments of the bridge which is proposed to be constructed across the river Karun4 in Iran using 3DEC. The rock sloping at 500 to 600 are composed of highly jointed rock mass and the joint spacing and orientation are varying at different locations. Since 3DEC is a three-dimensional numerical code, utilizes a Lagrangian calculation scheme to model large movements and deformations of a blocky system, allows for modeling of large movements and rotations, including complete detachment of rigid or deformable discrete blocks has been utilized for the analysis. The analysis has been... 

Recently, considerable efforts have been devoted to evaluation of seismic dynamic response of a circular tunnel. Conventional approaches have considered integral liners embedded in an elastic medium. In this study, we model a circular tunnel driven by TMB in homogeneous soil. Tunnel lining with 6 pieces of segments is analyzed by software in three dimensions. The results demonstrate that the stiffness difference between the segment and joints can enhance the internal forces of the segment significantly, which is crucial for the design of segments. The design of tunnel segment joints and joints between tunnels and portal structures are investigated by comparing with different parameters of... 

With the popular choice of using underground structures and tunnel in big cities and with significant damage in recent large earthquake; therefore more attention is given to the behavior of the underground structure in seismic area. The purpose of this thesis is to present the Soil-Tunnel-Structure Interaction analysis performed for different dynamic load condition. Therefore we modeled a 3D intersection part of two different tunnels in homogeneous soil by ABAQUS software. The soil and concrete structure of tunnel is modeled by three dimensional solid finite elements and the boundary of soil is modeled by three dimensional infinite elements with 8 nodes. The results demonstrate the geostatic... 

A brief overview of the proposed research, its aims, engineering relevance and applications Underground space has long been exploited through the history to fulfill different human necessities. Underground facilities built in areas subject to earthquake activity must withstand both seismic and static loads. Some underground structures have experienced significant damage in recent large earthquakes. Tehran is located in seismic zone and investigation and research on the subject has significant role in design and construction of underground spaces for earthquake loads. Underground structures are complex structures which consist of different parts Such as passage way and platform space. Passage... 

Three dimensional analyses have been carried out for predicting the behavior of the jointed rock slope of the abutments of the bridge which is proposed to be constructed across the river Karun4 in Iran using 3DEC. The rock overall slope angle is approximately 60 to 70 degrees, composed of highly jointed rock mass and the joint spacing and orientation are varying at different locations. Since 3DEC is a three-dimensional numerical code, utilizes a Lagrangian calculation scheme to model large movements and deformations of a blocky system, allows for modeling of large movements and rotations, and including complete detachment of rigid or deformable discrete blocks has been utilized for the... 

Deformation and Settlement of the ground surface and stability of large underground space is the main concern in the excavation under urban area. In order to control settlement and increase stability, it is necessary to use pre-Supporting system prior to excavation. Concrete Arc Pre-supporting System (CAPS) is one of the most useful pre-supporting methods which is used in exchange station of line 3 and 4 of Mashhad subway. Line 3 and 4 are parallel in Shohada square and the groundwater level is above the whole station structure. To analyze deformation of the ground due to excavation stages, the station was modeled in 2D and 3D by Abaqus. In this study, to estimate ground Deformation, we need... 

Tunnels are considered as one of the vital arteries of each country. In this concept, one of the most notable issues is designing of tunnel lining systems. Due to the increase of investments in tunnels and the progress of machinery and tunnel technology is needed for an optimal tunnel lining systems more than the past. The effect of initial lining system is not considered in designing of final lining systems, and this section is assumed to be omitted. In general, in this project, the final lining system of urban tunnels will be optimized by finite element method. This method is used by Abaqus software for analysis and the modeling. The purpose of this work is optimization of design lining... 

This research concerns a study of the interaction between tunneling and adjacent structures. Analysis is performed using a full two-dimensional finite element model, which takes into consideration the presence of adjacent structure with regard to distance to tunnel and diameter of tunnel during construction of the tunnel. The soil behavior is assumed to be governed by an elastic perfectly-plastic constitutive relation based on Mohr-Coulomb criterion with a non-associated flow rule. The research is composed of two parts. However, compatibility of each method with beam and solid continuum element models in two dimensional finite element (FE) analysis was investigated. The first part describes... 

Ground surface vibration produced by underground running trains is a known impact of rail traffic and has been widely considered in recent years. This vibration can vary in the range of almost 2–200 Hz on the ground surface or in tunnels. In other words, Tunneling in urban areas always has hazards. One of the most important hazards is propagated vibrations due to underground moving trains on surface structures. Purpose of this study is the investigation of moving subway train vibrational effect in line number one of Tabriz metro near station 11. 3D numerical finite element model (ABAQUS) is used in this study. Study of dynamics of a moving train can be considered in three models:... 

Recently, due to the major need of the development of underground spaces in dense urban areas, excavating tunnels near to the earth surface is arising. Therefore, there is a possibility that the new tunnels drill and construct in the vicinity or along the available tunnels. Thus, the interaction mechanism of this tunnels on each other and on land subsidence should be taken into consideration. In this research using ABAQUS finite element analysis software the interactions of the cross road subway station of Bimeh-Mehrabad airport in the line 4 of the Tehran city subway lines which is excavated using multistage drilling method is investigated. This model includes Eastern, Western and a... 

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... 

The purpose of this study is to analyze the stability and creeping behavior of rock salt in underground gas and oil reservoirs. Preparation of natural salt caverns and operating them can manipulate the initial state of previously existed stress and to produce deviatoric stresses around the cavern. New state of stress and with creeping behavior of rock salt, causes a significant decrease in cavern’s volume and damages the surrounding area. Reduction of internal minimum pressure of cavern, increases the intensity of mentioned problems. Geometrical characteristics of cavern can also be significantly effective in the magnitude of damages around the reservoir. For instance, Deflection of cavern...