Sharif Digital Repository

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:... 

Approximately, 60 percent of the world's populations are living at the distance of 60 kilometers of the coasts. In coastal zones, coastal aquifers are the most important resources of the available freshwater while expected that the short-term or long-term impacts of the climate changes threat such aquifers. In general, it is predicted that climate changes e.g. sea-level rise (SLR) cause to increase seawater intrusion (SWI) in the coastal aquifers. In this study, both continental and island coastal aquifers are considered. The objective of this research is the investigation of SWI behavior occurred in the coastal aquifers due to climatic change parameters and aquifer properties. For... 

This study investigates three-dimensional modeling of nanodroplets over chemically patterned surfaces. The pattern can be established by changing the contact angle on the surface. The problem is studied numerically by solving the thin film equations.Both the long-range and short-range inter-molecular interactions are considered. The numerical procedure is validated by using the theoretical studies. The effects of parameters such as the size of the droplets, the gradient of the surface, and the slip coefficient on the dynamics and speed of droplets and the shape of them during the motion are inspected.By examining the dynamics of the system it is revealed that the velocity of the droplets... 

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... 

Urbanization and increase in impervious areas owing to building construction, pavements of streets, parking lots and sidewalks, amount of surface runoff in cities has been rose. One of the environmental problems of Tehran during the rainfall is the high polluted runoff flowing in the city and eventually transfers pollution to aquifers. So in order to decline the consequences of this polluted surface runoff, it is crucial to understand how the runoff and pollution form. One way of decreasing pollution in runoff is hiring swales attenuation potential. In this study, problems associated with runoff, particularly in relation to the formation, transformation and removal of pollutants from runoff... 

Stability control of Rockfill dams during construction, first impoundment and during operation is of great importance. Increase in pore water pressure during construction and reservoir filling of rockfill dams with clay core can initiate or help the progress of the hydraulic fracture. Considering initiation of high excessive pore pressures while construction as an important causes of dam failure, precise estimation and analysis of It's variation will be necessary and will increase safety factor of dam stability.Horizontal and especially vertical displacements happening during Dam construction and reservoir filling and arching phenomenon in clay core while construction are the other factors... 

In this study, three dimensional analysis of soil slopes subjected to dynamic loading was conducted in order to investigate the interaction of soil-pipe system. For modeling of soil behavior, strain-dependent nonlinear elasticity along with Mohr-Coulomb plasticity was defined to the material and elasto-plastic behavior was used for the pipes. For dynamic modeling of soil slopes and analysis of buried pipelines, a Finite-Element-based software, ABAQUS was utilized. In this regard, first the numerical model was calibrated and verified based on the results obtained by physical shaking-table tests on a soil slope. Afterwards, a comparison was made between the results of numerical models and some... 

The mechanical behavior of unsaturated soils is much more complex than saturated soils and the effective stress principle cannot be initially applied to them. The soils found in most parts of Tehran, Iran, are unsaturated and this underlines the importance of having access to softwares capable of analyzing such soils; despite the fact that most available softwares are unable to do so. This thesis aims at adding one of the common unsaturated soil models to a geotechnical software and use that to model and analyze earth structures such as earth dams, foundations, embankments, etc. The Wheeler model (2003) for unsaturated soils is used in this study. This model takes advantage of two... 

Groundwater is the primary source of freshwater in many coastal areas and small islands around the world. The most important hazard to groundwater quality in coastal aquifers is seawater intrusion (SWI) resulting from over pumping, prolonged drought conditions and sea level rise due to climate change impacts. Numerical models of SWI are an important tool in the management of coastal aquifers. However, numerical modeling of SWI is one of the most challenging problems in groundwater hydrology. One of the reasons for the challenging nature of SWI numerical modeling is the relatively large level of uncertainty associated with the estimation of the model input parameters. This study focused on... 

In-situ tests are strongly recommended in site investigations, since laboratory studies are not sufficient for precise determination of soil parameters. Effects of soil disturbance on laboratory studies questions the validation of obtained soil parameters. In the in-situ tests, soil experience less disturbance and these tests are conducted in stress levels resembling to soil initial horizontal and vertical stresses. Also more volume of soil is tested by in-situ tests in comparison to laboratory studies. Pressuremeter instrument was invented by Menard (1954). In this test, a flexible cylinder is expanded in the cavity under fluid pressure and the volume and stress changes of the cavity are... 

Radiation evaluation in non-gray gaseous media is a very complicated issue. Previous researches have shown that the radiation properties of non-gray gases would strongly depend on the wavelengths. The gray gas assumption is the simplest model to calculate the radiation properties. Dispite simplicity, it is widely used in various industrial applications. In this model the gas radiation properties are assumed no to chang across all wavelengths. Evidently this would results in an inaccurate radiation modeling. Using the Spectral Line-based Weighted-sum-of-gray-gases model, SLW, the spectral behavior of radiation properties of gas is almost taken into account in computations. So the use of this... 

The purpose of presented thesis, is modeling of the buried pipelines in soil slopes under dynamic loading using experiments on the physical model. Hence, numerical models based on five physical models, which are built and experimented on Sharif University of Technology’s shaking table device, have been analyzed using ABAQUS finite element software. In each model, several pipes are buried in slope, and the angle-wise placement of pipes differs with respect to slope slide. For the purposes of modeling, the experiment box has been modeled as rigid body. In order to model the soil behavior, Strain –dependent nonlinear elasticity, and mohr-coulomb criterion, has been employed. In addition,... 

Groundwater is the most important freshwater resource in the coastal zones. There are some factors contaminate fresh groundwaters. Sea water intrusion (SWI) is one of the most important components of groundwater salinization. Also Submarine groundwater discharge (SGD) occurs when hydraulic gradient is from landside to seaside in coastal aquifers. There are many factors intensify SWI and SGD. In this research at the first part, coastline shape effect on SWI and SGD is investigated. For to this 4 different aquifers with different coastline shapes as stepped coastline, vertical coastline, steep slope coastline, and mild slope coastline are simulated with the same hydraulic parameters and... 

This study proposes a new metallic yielding damper for seismic applications. First, considering the damper proposed by curadelli in 2009 a simple lead yielding damper was manufactured to determine its maximum allowable axial deformation showing that it cannot tolerate suitable axial deformations. To solve this problem a telescopic damper with curadelli damper’s descriptions was manufactured and tested which increased the last damper’s allowable deformation 100%. Although new damper’s allowable deformation is twofold the old one, it was not enough for seismic applications. In the next step 6 dampers called lead shear dampers (LSD) with modified lead section were tested. LSD deformation... 

Land sourced marine pollution, overexploitation of living marine resources, destruction of habitat and introduction of harmful aquatic organisms and pathogens to new environment had been identified as the four greatest threats to the world’s oceans. Since invasive species can not be cleaned or absorbed in the ocean so, their effects on the environment are irreversible. Red tide is one of the invasive spieces and is a colloquial term used to refer to one of a variety of natural phenomena known as algal bloom. This phenomenon occur in estuarine, marine, or fresh water and algae accumulate rapidly in the water column and resulting in coloration of the surface water, varying in colour normally... 

Adobe structures are considered as masonry structures which are out of scope of 2800 Iranian code. Due to this code, since these structures are made of weak materials, they do not have a considerable resistance to earthquakes. Since these structures can be found all around Iran; therefore, seismic study of walls as an important component of these structures, is, indeed, necessary. During this study, cyclic tests on three types of adobe walls, without opening, with window-opening, and with door-and-window-opening with a scale of 2:3 were done to study their in-plane behavior and also their failure modes. Based on our observations, in these walls, because of small ratio of height to length,... 

Recently concrete filled steel tubular columns developed in the construction industry. In these types of columns, concrete and steel have efficient and complementary performance because of proper confinement provided by steel tube for concrete which leads to increase strength and ductility of concrete, also concrete prevents local and inward buckling of steel tube. CFST columns have several advantages over conventional reinforced concrete columns such as elimination of formwork and reinforcement, rapid construction, decrease in the column dimensions and saving extra floor space and also improvement in the load-carrying capacity, ductility and energy absorption ability. Despite the above... 

Pipe freezing has become well established in industry as a method of short-termisolation in order to carry out maintenance or repairs. It is often necessary to repair system components without plant shutdown or drainage of system having many piping structures which may have hazardous or expensive fluid. Therefore, a series of tests has been arranged to investigate the ice plug formation in two standard pipes with different diameter size. The freeze zone on the pipe has been created by means of an aluminum jacket which liquid nitrogen flows in it. In the tests the freezing time, amount of liquid nitrogen usage andthe pressure tolerance of ice plug have been determined. Moreover, the numerical... 

In modern era, standpoints about atrium design have been revolutionized. In modern architecture, atrium not only designed for illuminating purposes but also designed by natural ventilation and passive cooling policies. Numerous parameters are making role in thermal efficiency of Atrium. A couple of these parameters are Atrium shape and openings area. In high rise atria the lower level rooms enjoy the advantage of buoyancy-driven ventilation while the upper level rooms suffer from its lack or weak presence. One strategy to solve this problem is designing building with various opening area in different heights but manipulating the opening size is restricted by some facts. Excessive Opening’s... 

Soil liquefaction occurring in loose saturated sand deposits during seismic loadings is one of the most destructive earthquake-induced phenomena in the field of earthquake geotechnical engineering. Catastrophic destructions due to this phenomenon that have been observed in the earthquakes such as Kobe (1995), Chi-Chi (1999), etc. has led to extensive studies in this field. In case of soil slopes prone to liquefaction hazard, detailed analysis of this phenomenon requires considering soil-related factors (e.g. shear strength, relative density, permeability, slope geometry) on the one hand, and earthquake-related characteristics (e.g. amplitude, frequency, duration) on the other. Numerical...