Sharif Digital Repository

Objective: Business groups that create pyramidal ownership structures are a common form of corporate ownership in developing countries such as India, Chile, and Iran. These groups, along with the benefits they create, separate voting rights from cash flow rights; As a result, the ultimate owner will control them while having a small share of the cash flows of the companies in the lower layers of the group. This phenomenon provides tunneling motivation for controlling owners; incentivizing them to transfer resources and assets of their subsidiary companies (transferring resources from companies with less cash flow rights to companies with more cash flow rights) to gain private benefits at the... 

A physical model has been developed in the advanced soil mechanic lab of the sharif university of technology. This model has been used to investigate the thermo-hydro-mechanical behavior of the group energy pile, which was embedded in the unsaturated silty sand soil. This model contains a steel soil box, 4 aluminum piles, strain gauges, the total pressure cells, the thermocouples, and the mechanical load. Three sets of tests were conducted on these piles. In the first the thermal cycles were applied on 1 pile and in the second and third tests, the number of the energy piles was 2 and 3, respectively. The result has shown there was a permanent settlement at the end of the thermal cycles.... 

In many of the geotechnical engineering projects, such as embankments in earth dams and roads, the soil bears anisotropic loading. Even that the behavior of this material depends on the anisotropic loading, not many researches have investigated the effects of this phenomenon. The main objective of this research is investigation the effect of anisotropic loading induced by rotation angel of principal axes parameter under unsaturated conditions. Hence, shear strength of firoozkooh silt, in terms of deviatoric stress at failure under monotonic loading under different values of rotation angel of principal stress axes parameter and confining stress have been studied. For this purpose, silty... 

The ground experiences various hydraulic conditions under climate and groundwater level changes, and it becomes dry or wet frequently. The states of pore-water within the geomaterial, being signified in terms of suction and saturation degree, change during these variations, and consequently affect the soil behavior. The main objective of this research is investigation the effect of anisotropic loading induced by rotation angel of principal axes parameter under unsaturated conditions . Hence, shear strength of firoozkooh silt, in terms of deviatoric stress at failure under monotonic loading under different values of rotation angel of principal stress axes parameter and confining stress have... 

In this investigation, a series of cyclic simple shear tests were carried out in order to evaluate dynamic parameters of Babolsar and Toyoura sand at levels of saturation 25, 50, 75 and 100%. 96 tests were conducted using SGI type cyclic simple shear device. The specimens were cylindrical, with 7cm diameter and 2.2 cm height. The tests were performed under both drained condition (constant-load) at levels of saturation 25, 50%, and undrained condition at levels of saturation 75, 100%. All tests were performed under vertical consolidation stress of 50 and 150 kPa, relative density of 30 and 70% and cyclic shear strain of 0.5, 5 and 10%. The tests were shear strain-controlled with an... 

The most important step in current dynamic analysis of machine foundations is determining dynamic impedance functions. Impedance functions are defined as ratios of applied force or moment to induced displacement or rotation angle of foundation. In this research, horizontal dynamic response of foundation on homogeneous halfspace was investigated using physical modeling. Soil medium was built in a 1mx1mx0.8m steel box whose interior walls were covered by 0.1m of sawdust (a material with high damping). In order to prevent possible reflection of waves, this cover was extended to the box bottom with 0.2 m thickness. Sand raining method was used to build soil medium. In this method, with... 

Increasing requirements of industries and research institutes to analytical results of interaction soil-foundation related systems, reveals the importance of the dynamic impedance functions than ever before. The dynamic impedance function relations are presented for massless rigid foundations which is possible to obtain dynamic response of foundations for different frequencies and masses accordingly. In this study, the dynamic impedance functions were investigated using physical modeling tests on sandy soil with finite thickness soil stratum over bedrock. The tests were carried out inside a steel container of dimensions 110.8m in length, width and height respectively which was filled into... 

Since seepage-related problems account for the cause of more than forty percent of dam failure seepage analysis serves as one of the most significant stage in the design process of an embankment dam. Currently a steady seepage analysis in a typical or maximum cross section of the dam is formed instead of transient seepage analysis for simplicity. In this way, for the change of condition (unsaturated to saturated) in the first filling of dams and it’s effects on behavior and reaction of dams until the steady seepage condition established; the results of steady seepage analysis cannot be satisfactory. In this thesis, based on finite element method and with assumption of saturated-unsaturated... 

Dynamic impedance functions method is most recent approach in the analysis of soil-foundation dynamic interaction, and presented for massless rigid foundations. Impedance functions are frequency dependent functions, and used to obtain dynamic response of foundation with arbitrary mass subjected to dynamic loading of any frequency and magnitude. The important assumptions for appropriate useof mentioned method are rigidity of foundation and visco-elastic behavior of the soil beneath the foundation. In this study, experimental vertical impedance functions of square and circular foundations have been investigated,using physical modeling tests. A granular soil layer with finite thickness... 

Moderate to large magnitude earthquakes trigger hundreds to thousands of slope stability failures and landslides in coherent masses. In many earthquakes, landslides have been responsible for as much or more damage than all other seismic hazards combined. Earthquake-induced landslides have a detrimental impact on the serviceability of slopes by damaging nearby structures, roadways, utilities, power lines and communication networks. In this research large-scale shaking table model tests were conducted to study slope behavior under earthquake conditions on Sharif University shaking table. The model slopes were installed into a model box with a length of 3 m, width of 1 m, and height of 1.5 m. A... 

Evaluation of the compression wave velocity (Vp ) and small strains elastic modulii of various types of plastic concrete specimens in unconfined and triaxial compression tests using piezoelectric transducers was performed in this study. Plastic concrete consists of aggregates, cement, water and bentonite, mixed at a high water cement ratio, to produce a ductile material. It is used for creating an impermeable cut-off wall for seepage control in highly permeable dam foundations. A plastic concrete cut-off wall acts essentially as a barrier to stop or reduce the groundwater flow. In this study the effect of specimen age, water-cement ratio, bentonite-cement ratio, confining pressure, wave... 

This research are divided into the two main parts. In the first part, effective parameters for prediction of 28 days strength of plastic concrete have been determined. In this part, data mining operation was done on some informations which was sent from Silveh Dam construction site. In dam construction site, for quality control of plastic concrete which used in building of cut off wall some tests are done regurlarly in 7 and 28 days of concrecte production. In first part we used artificial neural network for predicting of relation between 28 days strength parameter and varios parameters of dam mixture content. The results has shown that the most effective parametes on 28 days strength... 

The purpose of this dissertation is investigation of dynamic behavior of buried pipelines in slopes in landslide. For this purpose four physical models were made on shaking table of Sharif University of Technology. In each of the models some pipes were buried in slope. In these models the pipes were placed in different angles regarding to slope direction. Simulation laws suggested by Iai (1989) were used in these models. Babolsar sand was used for modeling the slopes. Aluminium pipes with outside diameter of 16 millimeters and thickness of 1 millimeter were implemented to model steel pipelines. In this investigation simple supports were used at the end of the pipes, considering the... 

Studying of slope stability under dynamic loading such as earthquakes is one of the critical issues. This importance is attributed to many of the slopes are located in urban areas, either around them or in the important buildings and infrastructure. Thus, evaluation of slope’s behavior is very essential. On the other hand, preparing fundamental arrangements to improve the current situation, surrounding and buried areas in the slope is necessary.
In this study, a physical model of Tehran's slopes by 0.1 ratio with pipes that have been retrofitted by plastofoam developed. This model was tested on the shaking table under dynamic loading. The dimensions of the slope were 1 meter width, 3... 

Increasing requirements of industries and research institutes to analytical results of interaction soil-foundation related systems, reveals the importance of the dynamic impedance functions than ever before. The dynamic impedance function relations are presented for massless rigid foundations which is possible to obtain dynamic response of foundations for different frequencies and masses accordingly. In this study, the dynamic impedance functions were investigated using physical modeling tests on sandy soil with finite thickness soil stratum over bedrock. The tests were carried out inside a steel container of dimensions 1*1*0.8m in length, width and height respectively which was filled into... 

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,... 

Evaluation of seismic slope stability is very important because it has a decisive role in estimating the earthquake damages. According to the past studies medium to large earthquakes, usually cause thousands landslides and many casualties and financial damages. Since nearly half a century ago, several methods have been developed for predicting the occurrence of landslides and permanent movements, but due to the influence of many parameters on the seismic stability of the slopes further researches is needed.In present study, to investigate the dynamic behavior of the slopes, three physical models of slopes had been made on shaking table in Sharif University of technology. These slopes have... 

Direction of loading and magnitude of the intermediate principal stress have significant effect on the soil responses. In many of in-situ loading the direction of major principal stress is not coincide to the deposition direction of the soil. Also, the magnitude of the intermediate principal stress should be exerted in the three dimensional loading condition. A reliable assessment of the soil behavior and a good estimation of the soil parameters need to do tests in similar condition with in-situ. So the testing apparatus should be able to control the loading direction in various stress paths. Typical equipments used in the geotechnical laboratory have not the ability to control the magnitude... 

In many of the geotechnical engineering projects, such as construction of embankments and roads, soil is compacted with different water contents. Difference in compaction water content leads to different dynamic behaviors under cyclic loadings like earthquake and traffic. On the other hand, the magnitude and the direction of principal stresses on soil element, affect the dynamic response of the soil. The main objective of this research is to study the effects of compaction water content on dynamic properties of soil in anisotropic loading conditions. Therefore, the dynamic parameters of Babolsar sand, including shear strain amplitude, shear modulus and damping ratio under induced anisotropic... 

Soils have an anisotropic response, and mechanical and dynamic properties of this material are greatly dependent on the direction and magnitude of principal stresses. A reliable assessment of the soil behavior and a good estimation of the soil parameters need to perform tests in similar condition with in-situ. From all the devices used for studying anisotropy of soils, hollow cylinder apparatus is the only apparatus that enables an independent control of both the direction and magnitude of the principal stresses. Moreover, one of the most controversial topics in the unsaturated soil dynamics is determining the shear modulus and damping ratio which are used for assessing many geotechnical...