H. Ghasemzadeh | K.N.Toosi University of Technology (original) (raw)

Papers by H. Ghasemzadeh

Stress waves contain useful information about the properties of porous materials; they can be rec... more Stress waves contain useful information about the properties of porous materials; they can be recovered through different non-destructive testing methods such as crosswell, vertical seismic profile, borehole logging as well as sonic tests. In all these methods, it is crucial to assess the effects of frequency on wave attributes including velocity and intrinsic attenuation. The dependency of permeability on frequency which is known as dynamic permeability and its effects on wave attributes of compressional waves are investigated in the present paper. Utilizing the dispersion relation derived for compressional waves, it is shown how the velocity and intrinsic attenuation of waves propagated in water saturated sand may be influenced by dynamic permeability. In low frequency range (viscous dominated flow regime), the dynamic permeability behaves like Darcy steady-state permeability and its effects on wave attributes are negligible. However, deviations from Darcy permeability start to oc...

Minerals Engineering

Abstract Several mechanisms contribute to changes in the performance of oxide copper heaps. These... more Abstract Several mechanisms contribute to changes in the performance of oxide copper heaps. These include physical, biological, chemical and thermal interactions between sulfuric acid and the formation of soil particles. A series of experimental studies was conducted by simulating the column leaching process in the laboratory. The leaching of selected gravel and crushed copper oxide ores from two copper mines was carried out to measure their permeability and strength. The influence of effective parameters on gravel clogging was studied and the clogging coefficient was estimated with time. Furthermore, the ratio of particle reduction (RPR) caused by acid seepage was evaluated and an equation for the internal friction angle of ore particles over time was generated. The present study shows significant reductions of gravel permeability (28% after five months leaching) and friction angle of ore particles (25% after eight months leaching). The effects of sulfuric acid flow on the hydro-mechanical properties of oxide copper heap soils could enhance the accuracy of slope stability design and drainage layers design in industrial heap leaching systems.

Engineering Analysis with Boundary Elements

Abstract In this research, a combination of the numerical manifold method (NMM) and boundary elem... more Abstract In this research, a combination of the numerical manifold method (NMM) and boundary element method (BEM) is presented for solving plane elasticity problems to benefit from the advantages of both methods. For this goal, the domain of the problems is divided into two regions, each region is analyzed separately, and finally, equilibrium and compatibility conditions are controlled in the interface by the iteration method. 1D quadratic boundary elements and 2D quadratic, cubic and quartic ones in the form of triangular shapes are utilized in the boundary element and manifold methods, respectively. The proposed method is verified by calculating the displacements and stresses resulting from the application of static loads in five different numerical problems. Comparison of the numerical results shows that the suggested method is very efficient and accurate.

Linnaeus Eco-Tech

Many environmental issues involve transport of contaminants in unsaturated porous soil media. Uns... more Many environmental issues involve transport of contaminants in unsaturated porous soil media. Unsaturated flow plays a significant role in wastewater infiltration and treatment. Transport of contaminants in unsaturated porous subsurface media is of significant importance due to the risks which contaminants pose to the environment. Mechanics of unsaturated soils is perhaps the most important issue in prediction of unsaturated flow including contaminant transport in the environment. The SWCC, “soil water characteristic curve”, can be used to determine various characteristics of the unsaturated soil media. In fact, it illustrates the relationship between soil suction and moisture content. Experimental methods for assessment of the SWCC are often time consuming and expensive. The SWCC can be estimated using specific characteristics of soils to avoid the costs of experimental methods. This paper aims at demonstrating that the SWCC for cohesive soils can be estimated using the PI, fine co...

Geotechnical and Geological Engineering, 2016

Chemical soil stabilization method can be applied as a remediation technique for contaminated soi... more Chemical soil stabilization method can be applied as a remediation technique for contaminated soils. Since stabilization method can improve the soil geotechnical properties, the effect of contamination should be investigated on soil strength improvement with this method. This paper studies the effect of different additives such as lime, cement, rice husk ash and RRP-235 Special on the geotechnical properties of a diesel fuel contaminated kaolinite. A series of unconfined compressive strength and direct shear tests were performed on the contaminated kaolinite stabilized with additives in the amounts of 1, 3 and 5% by soil dry weight. Results showed that an increase in diesel fuel as contaminant up to 10% by dry weight of the soil had adverse effects on lime and rice husk ash stabilized soil strength and cohesion, while it increased the strength and cohesion of cement stabilized soil. The friction angle of all the lime, cement and rice husk ash stabilized samples was decreased with increasing the contaminant. An increase in RRP-235 Special had no impact on the soil strength properties.

Unsaturated Soils 2006, 2006

Rock Stress and Earthquakes, 2010

Applied Mathematical Modelling

Journal of Cleaner Production

Numerical Methods in Civil Engineering

Canadian Journal of Soil Science

Bearing capacity is often calculated in dry or saturated conditions, leading to overconservative ... more Bearing capacity is often calculated in dry or saturated conditions, leading to overconservative designs, for a wide range of climates in the world. Extensive researches show that bearing capacity is significantly affected by the soil matric suction. However, in most of the presented models, uniform (and sometimes linear) suction distributions are taken into account for computing the bearing capacity. Also, there is no exact solution in the residual zone of unsaturation. In the present study, a simple method is proposed to predict the bearing capacity of footings placed on unsaturated soil, using the limit equilibrium concept. Linear and uniform variations of matric suction are considered in computations, as well as the nonlinear suction distribution. The framework of the proposed model is analogous to Terzaghi’s equation, and a novel factor is developed, during calculations, as the suction bearing capacity factor. In the case of full saturation, the proposed model is simplified to ...

International Journal for Multiscale Computational Engineering

International Journal of Civil Engineering