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A suction-controlled ring device to measure the coefficient of lateral soil pressure in unsaturated soils
, Article Geotechnical Testing Journal ; Volume 44, Issue 1 , 2020 ; Garakani, A. A ; Golshani, A ; Mirzaii, A ; Sharif University of Technology
ASTM International
2020
Abstract
A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring...
Behavior of dry and saturated soils under impact load during dynamic compaction
, Article 16th International Conference on Soil Mechanics and Geotechnical Engineering: Geotechnology in Harmony with the Global Environment, ICSMGE 2005, Osaka, 12 September 2005 through 16 September 2005 ; Volume 3 , 2005 , Pages 1245-1248 ; 9059660285 (ISBN); 9789059660281 (ISBN) ; Shahir, H ; Ghassemi, A ; Sharif University of Technology
2005
Abstract
Dynamic compaction is a widely used soil improvement method in dry and/or saturated soils. Despite its vast application, its design basis is still empirical and the mechanisms that are involved in the procedure are not fully understood. A fully coupled dynamic finite element code has been developed in order to clarify the ambiguities in the process and predict the strain/displacement field in the ground, determine depth and degree of improvement, and also calculate the pore pressure variation during the process. This model can be used as a rational design tool for dynamic compaction projects
Collapsible Behavior of Gorgan Loess Using Odeometer
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
In nature, there are types of soils that when goinging under stress at constant moisture, or increase of moisture at constant stress, or change of both characters, they show a sudden and high level decrease in their volume. These type of soils are named as Collapsible soils. Iran is one of the countries that at some parts of its land collapsible soils are found. In this research by using of laboratory equipments, the volume change behavior of collapsible loess soils of Gorgan plain (North of Iran) is evaluated under increase of water content and inundation stress. In these experiments, the usual odeometer cell has been used for exploring the behaviour of collapsibility and volume change of...
Seismic performance of nonlinear soil-structure systems located on soft soil considering foundation uplifting and soil yielding
, Article Structures ; Volume 28 , December , 2020 , Pages 973-982 ; Ghannad, M. A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In most of researches on soil-structure systems, it is assumed that the foundation is bonded to the ground where no foundation uplift is allowed. Uplifting makes changes in force–displacement behavior of the soil-structure systems, which in turn alters structural demands. In this research, a set of non-dimensional parameters is considered which controls the behavior of uplifting systems. The effects of foundation uplift on response of soil-structure system are investigated parametrically through time history analysis for a wide range of systems subjected to harmonic excitation and also ground motions recorded on soft soil with predominant period. It is seen that the response of systems with...
Implementation of image processing technique for measuring membrane penetration in triaxial testing on gravelly soils
, Article 19th International Conference on Soil Mechanics and Geotechnical Engineering, ICSMGE 2017, 17 September 2017 through 22 September 2017 ; 2017 , Pages 381-384 ; Shahcheraghi, S. A ; Sharif University of Technology
19th ICSMGE Secretariat
2017
Abstract
The volume change that occurs due to membrane penetration into peripheral voids of gravelly specimens during hydrostatic compression test in a conventional triaxial apparatus is studied by performing a set of hydrostatic compression tests on gravelly specimens with different initial relative densities. During the isotropic loading on the specimens, the total volume changes of the specimens were determined by measuring the amount of water seeping out of the specimens at different loading steps. Image processing technique was implemented simultaneously to determine the skeletal volume changes of the specimens. In this regard specimens were compressed to isotopic pressures from 10 to 500 kPa...
Evaluation of the Behaviour of Collapsible Soils in Saturated and Unsaturated Oedometer Tests – Case Study of Gorgan Loess
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Collapsible soils are kinds of problematic soils which are susceptible to large and sudden reduction in volume upon wetting. A manifest kind of these soils is loess; catastrophic settlement of structures which are built upon it has been observed when the soil becomes wet. In this investigation the collapse potential of samples of loess taken from Gorgan, Golestan, Iran, has been studied by using unsaturated odometer tests under controlled matric suction. To this end, two modified odometer apparatus with the capability of controlling the matric suction, have been designed and developed. Undisturbed samples of soil have been tested under K0 condition, while the matric suction, volumetric...
Study of Stability of Unsaturated Railway Embankment Founded on Saline and Desalinated Loess
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
Loess with a dispersion potential is one of the problematic soils of Iran. This study aims to investigate the impact of dispersion potential on the water flow in a three-phase medium and determine the effect of salinity on the stability of an unsaturated railway embankment by employing the soil-water retention curves of the materials. To satisfy this objective, the natural dispersive loess of the Chabahar region is desalinated in this study and the hydraulic properties of both saline and desalinated soils are comprehensively investigated. First, the soil-water retention curves of the materials are measured through the filter paper test method. Afterward, the saturated hydraulic conductivity...
In-situ Stabilization of Collapsible Soil Using Grouting
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
The aim of this study is to investigate the feasibility of in-situ stabilization of collapsible soil using grouting. Collapsible soils are a type of problematic soils that are found mostly in arid and semi-arid regions. Loess is stable in its natural unsaturated state, but when it is inundated under a sufficient stress, it will suffer a severe volume reduction due to reduction in matric suction and dissolution of its cementious bonds in water. So, finding a method for in situe remmediation of such a soil is very important especially for the built environments. The collapsible soil used in this study is a loessial soil sampled from the northeast of Golestan province, Iran. The undisturbed...
Hydro-mechanical behavior of collapsible soils in unsaturated soil mechanics context
, Article 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015, 9 November 2015 through 13 November 2015 ; November , 2015 , Pages 25-40 ; Association for Disaster Prevention Research; et al.; Fukuoka Convention and Visitors Bureau; Japan Society for the Promotion of Science - Grant-in-Aid for Publication of Scientific Research Results; Kyushu Regional Planning Association; The Maeda Engineering Foundation ; Sharif University of Technology
Asian Regional Conference on Soil Mechanics and Geotechnical Engineering
2015
Abstract
This paper is related to the studies taken place during last decade to understand the intact behavior of a Collapsible Loess subjected to loading and wetting at Advanced Soil Mechanics Laboratory of Sharif University of Technology, Tehran, Iran. In this regard intact block samples are carefully taken from Hezar Pich Hill in the city of Gorgan, Iran, and various tests are performed on undisturbed specimens recovered from the intact block samples. In this way three automated unsaturated oedometer are built and a conventional triaxial apparatus is upgraded to a fully automated unsaturated triaxial device to accommodate rigorous and different stress and wetting path with continuous data...
Interface behavior between carbon-fiber polymer and sand
, Article Journal of Testing and Evaluation ; Volume 44, Issue 1 , 2016 , Pages 385-390 ; 00903973 (ISSN) ; Ouria, A ; Desai, C. S ; Javid, N ; Toufigh, V ; Saadatmanesh, H ; Sharif University of Technology
ASTM International
2016
Abstract
Interface shear strength between soil and structural materials is dependent on the confining pressure. To increase the confining pressure, different methods of reinforcement and materials, such as carbon-fiber-reinforced polymer (CFRP) can be used. The shear strength of CFRP-improved soil is dependent on the interface properties of the soil and CFRP. The objective of this study is to investigate the interface properties (friction angle and adhesion) of sand and FRP experimentally using the direct shear test apparatus. To increase the surface roughness to improve the interface properties, a layer of sand was placed on saturated carbon fiber during the curing period [spark plasma sintering...
Feasibility of using electrokinetics and nanomaterials to stabilize and improve collapsible soils
, Article Journal of Rock Mechanics and Geotechnical Engineering ; Volume 11, Issue 5 , 2019 , Pages 1055-1065 ; 16747755 (ISSN) ; Haeri, S. M ; Mahvelati, S ; Fathi, A ; Sharif University of Technology
Chinese Academy of Sciences
2019
Abstract
Loess as a subcategory of collapsible soils is a well-known aeolian deposit generally characterized as a highly-porous medium with relatively low natural density and water content and a high percentage of fine-grained particles. Such collapsible soil sustains large stresses under a dry condition with natural water content. However, it can experience high and relatively sudden decreases in its volume once it reaches a certain water content under a certain load and therefore, the natural condition of the soil might not be suitable for construction if the possibility of the exposure of the soil to excessive water exists during the lifetime of the project. This research presents the utilization...
Application of a bond model for constitutive modeling of cemented gravely sands
, Article 12th International Conference on Computer Methods and Advances in Geomechanics 2008, Goa, 1 October 2008 through 6 October 2008 ; Volume 1 , October , 2008 , Pages 732-738 ; 9781622761760 (ISBN) ; Haeri, S. M ; National Institute of Disaster Management (NIDM); American Society of Civil Engineers (ASCE) ; Sharif University of Technology
2008
Abstract
In this paper the framework for a constitutive model which is developed for a cemented gravely sand is presented. The model is based on separation technic namely the separation of the behavior to the uncemented soil and the cemented bonds. They are combined in a manner to satisfy the deformation consistency and energy equilibrium equations. The uncemented soil behavior is modeled using a modified model originally proposed by Pastor et al. (1985) for sandy soils. Also, based on the results of the experiments, a new model for the bonds is developed. Combination of these two parts results in the modeling of the behavior of cemented gravely soils in drained and undrained states
Steady state and liquefaction characteristics of gravely sands
, Article Geotechnical and Geological Engineering ; Volume 23, Issue 2 , 2005 , Pages 141-156 ; 09603182 (ISSN) ; Hamidi, A ; Sharif University of Technology
2005
Abstract
Liquefaction of loose and saturated soils during earthquakes and strong ground motions has been a major cause of damage to buildings and earth embankments as well as other civil engineering structures. In order to evaluate the liquefaction potential and steady state characteristics of gravely sand of south west Tehran, a subsoil exploration program conducted dividing the region into 10 zones. In each zone of 500 m × 500 m a borehole of 20 m deep was drilled. SPT was performed at one meter intervals in each borehole and a total of 200 samples were recovered. Soils of similar grain size distribution have been considered to have similar steady state characteristics,therefore consolidated...
Stabilization of Collapsible Soil with Nano-Material and Injection using Electrokinetic Procedure .Case Study: Gorgan Loess
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Collapsible soils, a kind of which is Loess, are mainly in silt size in the nature, and are present in many part of Iran, such as Golestan, Semnan, Khorasan, Yazd, Kerman, Hormozgan, Sistan and Balouchestan provinces. when the water content of the soil is lower than a critical water content, the soil shows high shear strength. However, increase in water content due to leakage of water, wastewater or heavy rains in the presence of enough induced pressure, when a certain coupled hydro-mechanical condition is reached, will result in a sudden collapse or excessive deformation. Hence, improvement or stabilization of this kind of soil is of high importance. In this research, specimens are prepared...
Estimating the drainage rate from surface soil moisture drydowns: application of DfD model to in situ soil moisture data
, Article Journal of Hydrology ; Volume 565 , 2018 , Pages 489-501 ; 00221694 (ISSN) ; Tajrishy, M ; Brocca, L ; Massari, C ; Ghazi Zadeh Hashemi, S ; Ciabatta, L ; Sharif University of Technology
Abstract
The large heterogeneity in soil surface conditions makes it impracticable to obtain reliable estimates of soil hydraulic parameters for areas larger than few squared kilometers. However, identifying these parameters on a global scale is essential for many hydrological and climatic applications. In this study, a new approach named Drainage from Drydown (DfD) is proposed to estimate the coefficients of drainage using soil moisture observations. DfD firstly selects multiple drydown events when surface runoff and evapotranspiration rates are negligible compared to the drainage rate. Secondly, by inverting the soil water balance equation, the drainage coefficients are obtained. Synthetic...
Numerical investigation of stability of deep excavations supported by soil-nailing method
, Article Geomechanics and Geoengineering ; Volume 16, Issue 6 , 2021 , Pages 434-451 ; 17486025 (ISSN) ; Maleki, J ; Aghakhani, N ; Yousefi, M ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
Deep excavation in urban areas can cause instability problems due to significant settlement at the ground surface and large movements at the excavation facing walls. One of the most popular methods used to stabilise these excavations is utilising soil-nailing method. This method has also been widely used to stabilise natural slopes and earth retaining structures. Because of the complexity involved in the mechanism of this stabilising system due to interacting effects of the soil, nails, grout and shotcrete, numerical modelling with high accuracy should be used to analyse the behaviour of the soil-nailed walls. Considering all aspects of soil-structure interaction in the present research, a...
Hysteresis of soil water retention and shrinkage behaviour for various salt concentrations
, Article Geotechnique Letters ; Volume 11, Issue 1 , 2021 , Pages 21-29 ; 20452543 (ISSN) ; Nasiri, H ; Sharif University of Technology
ICE Publishing
2021
Abstract
Laboratory investigation on the influence of solute concentration on the soil water-retention curve (SWRC) and volumetric behaviour of expansive soils has received much attention in recent years due to increasing environmental pollution. However, most studies only considered applying wetting or drying path with almost no attention to hydraulic hysteresis. Furthermore, these studies have focused on examining expansive soils and only marginal effort has been devoted to collapsible soils. Therefore, the main objective of this study is to systematically explore the SWRC and shrinkage characteristics of an artificially made collapsible soil at various molar concentrations. The tests were...
Assessing the Hydro-Mechanical Behavior of Undisturbed Collapsible Soils by Conducting Unsaturated Odeometer Tests Case Study: Northeastern Loess of Golestan Province
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
The deposits in many regions in Iran, particularly eastern zones like Golestan, Semnan, Yazd, Kerman, Hormozgan, Sistan and Baluchestan provinces consist of deposits of loess, which are categorized as collapsible soils. This kind of soil show sufficient shear strength and low deformability in dry or natural condition. However, if a structure is built on the soil and water seeps or infiltrates into the soil due to several reasons such as sewer leakage, water seepage or heavy precipitations in a way that its moisture reaches to a critical value, the interparticle bonds may break or the present suction in the soil may decrease in a way that the soil experiences sudden collapse, which may result...
Geotechnical characterization and collapsibility of a natural dispersive loess
, Article Engineering Geology ; Volume 250 , 2019 , Pages 89-100 ; 00137952 (ISSN) ; Kiani, M ; Sadeghi, M ; Jafarzadeh, F ; Sharif University of Technology
Elsevier B.V
2019
Abstract
During preliminary investigation phase of the national Chabahar-Zahedan railway line, serious geotechnical problems including non-uniform settlements, tensile cracks, and local collapse were reported in parts of the path near the coastline. A follow-up field investigation revealed that the in-situ soil at construction site has a metastable structure being sensitive to saturation and loading. Therefore, a comprehensive series of physical, chemical, electro-chemical, and geotechnical tests were conducted to classify and characterize the soil properties and behavior in its natural state. The natural soil was classified as a clayey loess with moderately dispersive to dispersive characteristics....
Enzymatic and soil burial degradation of corn starch/glycerol/sodium montmorillonite nanocomposites
, Article Polymers from Renewable Resources ; Volume 11, Issue 1-2 , 2020 , Pages 15-29 ; Gilak Hakimabadi, S ; Nabavi, F ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
In this study, effects of glycerol (10, 20, and 30 wt%) and Sodium Montmorillonite (Na-MMT) (0%, 2.5%, and 5%) contents on the degradation of corn starch polymers were investigated. Films were prepared by casting corn starch solution using a modified method to enhance the nanoclay distribution. Biodegradability studies were performed by enzymatic and burial tests using pristine and enriched soils. The biodegradability of samples in pristine soil was faster, and all samples were fully degraded in 6 months. The effect of nanoparticles on the mass reduction in degradation was more pronounced than that of glycerol. In all glycerol concentrations, Na-MMT addition increased tensile strength. FTIR...