Sharif Digital Repository

Global warming and climate change significantly affect ground temperature and flow patterns. Moreover, areas prone to cracking experience intensified temperature and moisture variations. Therefore, the aim of this study is to investigate ground temperature and moisture dynamics considering soil-atmosphere interaction through a coupled thermo-hydraulic analysis. Heat transfer, advective, and non-advective fluxes were simulated using CODE_BRIGHT finite element program to study water flow and energy transfer within the soil. Statistical analyses were conducted using an existing dataset to match the crack geometry with previous studies and find the best distribution for the width-to-depth ratio... 

Wetting hydrological processes are relevant to a considerable number of natural hazards, including landslides, dam breaks, surface runoff after floods, etc. The notable difference between wetting and drying soil–water retention curves (SWRC) has been attributed to the hysteresis phenomenon. Although recent studies confirm enhanced impurity levels of permeating fluid, most modeling approaches simply consider water retention along the drying path and neglect the impurity of pore water. Therefore, the main objective of this paper is to introduce a new water retention model along the wetting path by taking the osmotic potential into account, reflecting the influence of dissolved salts. The new... 

Coupled fluid–solid phase continuum problems associated with large deformation as geotechnics experts encounter in slope stability problems have been extensively reviewed. This has been done with a view to exploring the most efficient numerical approach to solving them for the sake of our environment. Decades ago, analytical solutions known as the limit equilibrium methods (LEM), e.g., Navier–Stokes and the likes were celebrated with the level of mathematical solutions they offered. To overcome the limitations of the LEM in handling more complex slope failure problems, numerical solutions were born, which solved these problems by method of mesh discretization. However, mesh discretization... 

Clayey soils are widely used as barriers to control leachate leakage in landfills. Chemico-osmosis is one of the important phenomena influencing soluble contamination transport through clay barriers acting as a membrane. The membrane ability to restrict contamination transport is referred to as membrane efficiency. Experimental reports have revealed that membrane efficiency is a function of soil void ratio and contamination concentration. However, the currently used empirical function expresses the membrane efficiency simply in terms of average concentration. Therefore, the merit of this study is to enhance the reliability of this function to take into account various concentrations and void... 

Geosynthetic clay liners (GCLs) are synthetic materials manufactured and widely used in geotechnical and geoenvironmental engineering due to their very low permeability and ease of use. As the most critical function of GCLs are their isolating features, it is of primary importance to precisely predict their water retention properties, especially when subjected to impure water having considerable solute concentrations because of landfill leachate. Despite numerous efforts on analytical modeling of bare soil-distilled water retention, less attention has been given to the retention characteristics of GCLs. Therefore, the current study's primary goal is to introduce a new analytical GCL-water... 

A state-of-the-art review has been conducted in this work on soil constitutive modeling, which has emphasized on: soil type, ground-water conditions, loading conditions, structural behavior, constitutive relation discipline, and dimensions. By extension also, the soil constitutive applications were reviewed on the bases of: single discipline dealing with soil mechanical properties constitutive modeling which included slope stability problems, bearing capacity, settlement of foundations, earth pressure problems, soil dynamics, soil structure interaction, thermal and hydrological conditions; bi-discipline (coupled problems) which solve problems related to thermomechanical (freeze/thaw... 

The soil water retention curve (SWRC) or soil–water characteristic curve (SWCC) is a fundamental feature of unsaturated soil that simply shows the relationship between soil suction and water content (in terms of the degree of saturation and volumetric or gravimetric water content). In this study, the applications of the SWRC or SWCC have been extensively reviewed, taking about 403 previously published research studies into consideration. This was achieved on the basis of classification-based problems and application-based problems, which solve the widest array of geotechnical engineering problems relevant to and correlating with SWRC geo-structural behavior. At the end of the exercises, the... 

Land subsidence, as a gradual settling of the ground surface, has become a threatening hazard to many infrastructures and lifelines. Among them, electricity dispatch centers (EDC) are considered the heart of a typical power transmission system, closely related to both domestic and industrial aspects of society. Therefore, this study aims to systematically explore early warnings and damages imposed on EDCs in Tehran. A combination of field reconnaissance and InSAR time series analyses are adopted to correlate subsidence-induced damages with several triggering mechanisms, such as the dynamic effects of subways and extra groundwater exploitation. Accordingly, spatially- and... 

This study proposes a new approach to incorporate motion duration in incremental dynamic assessments. In the proposed methodology, at each intensity level, a simulation-based approach which is verified with actual data is employed to determine the median duration and the median acceleration spectra of ground motions expected to occur at the site. Afterward, at each intensity level, artificial or spectrally matched motions are produced based on the median acceleration spectra and the median duration, indicating that different intensity levels are directly covered by the generated artificial or adjusted motions rather than just scaling up and down a set of recorded ground motions. In the... 

A tailings dam is normally constructed through self-consolidation with minimum compaction effort. Accordingly, special attention to the ultimate limit design in assessing the tailings dam instability condition is of primary importance. Furthermore, the existence of pore fluid chemical contaminants with high concentrations makes soil hydraulic and shear resistance properties subject to considerable changes.Therefore, this study aims to investigate the stability of a tailing dam using saturated-unsaturated flow analysis under 0.2 and 0.6 M sodium chloride solutions and pure water as a benchmark. To make the analyses as realistic as possible, recently developed solute-dependent hydraulic... 

This study investigated the fabrication and characterization of two new zinc-titanium-based alloys. The Zn-xTi alloys (x = 4 and 10 wt%) were mechanically alloyed by powder metallurgy for 10 h. The spark plasma sintering (SPS) method shaped the resulting powder. The fabricated samples were evaluated in terms of morphology and structure by XRD, SEM, and microhardness tests. The obtained parts’ corrosion resistance and biological behavior were also examined by potentiodynamic polarization analysis, electrochemical impedance spectroscopy (EIS), and MTT tests. The results showed that alloying increased the hardness compared to pure zinc samples. The corrosion test results indicated higher... 

In engineering practice, land subsidence is considered a threat to the infrastructure and lifelines massively distributed globally. In this study, a combined methodology of full consistency decision-making (FUCOM) and the geographical information system (GIS) was employed to assess the vulnerability of Iran to subsidence. Accordingly, a new hierarchical FUCOM-GIS framework was developed. The FUCOM was first used to evaluate the weight of various causative factors. Afterward, the GIS was employed to superimpose several layers to produce a land subsidence susceptibility map (LSSM) of Iran. The results revealed water stress, groundwater depletion, soil type, geological time scale, and rainfall... 

The soil water retention curve (SWRC) provides information for a wide range of geoenvironmental problems, such as analyses of transient two-phase flow, the bearing capacity and shear strength of unsaturated soils. Many past studies have shown experimentally the effects of stress on the SWRC. Unfortunately, direct stress-dependent water retention measurements are relatively time-consuming and generally require special equipment and a certain level of expertise. This study primarily aimed to develop a novel predictive framework within the context of soft computing to capture the dependency of the SWRC on several variables, with an emphasis on stress and soil type. To achieve this, the three... 

This paper presents the effects of a non-uniform magnetic field on the hydrodynamic and thermal behavior of ferrofluid flow in a wavy channel by 3D numerical simulation. The wavy surfaces at the top and bottom of the channel are heated by constant heat fluxes. Moreover, the sidewalls are adiabatic. In the wavy section, in the perpendicular direction of the main flow, the magnetic field that linearly varies along the direction of the main flow is applied. The mathematical model that is consistent with the principles of ferrohydrodynamics and magnetohydrodynamics is used for the problem formulation. The results indicate that the wavy wall enhances the heat transfer rate on the bottom of the... 

In this work, phosphorus-31 and aluminum-27 nuclear magnetic resonance techniques were used to characterize the distribution of soluble aluminophosphate species in methanol + water and ethanol + water mixtures. The assignment of the peaks to alu-minate species was attempted, clarifying earlier work and producing information on the different aluminophosphate complexes. Nine peaks were observed at -0.41, -6.4, -7.5, -7.9, -13.1, -13.9, -16.6, -18.1 and -20.6 ppm. Four new peaks appeared in the 31P NMR spectra of the alcoholic aluminophosphate solutions and their intensities changed with changes of the alcohol:water volume ratio. These new peaks were observed in the presence of methanol or...