Showing 68 results for kh
Habib Shahnazari, Mahmoud Fatemiaghda, Hamid Reza Karami, Mehdi Talkhablou,
Volume 14, Issue 5 ( English articles 2020)
Abstract
The present work is conducted to investigate the effect of texture and carbonate content on internal friction angle of carbonate soils. Carbonate soils are majorly found in the bed of shallow waters and also offshores in tropical regions. Recently there is a huge construction projects including oil and gas extraction platform and facilities, harbors, refineries, huge bridges and other big construction projects in many offshore and onshore areas around the world. One of these area is located on southern part of Iran. We collected soil samples from different parts of northern coasts of Persian Gulf, then the following experiments were performed, carbonate content, three-dimensional grain size, angularity, relative density & direct shear. The results showed that the average of internal friction angle of carbonate soil is higher respect to known silicate sands. This angle is affected by effective grain size, grain angularity, and calcium carbonate content. Based on the experimental results of this study, one of the results was that the internal friction angle of carbonate soils decreases as their effective size of soil aggregates increases.
Ramin Sarikhani, Amin Jamshidi, Artimes Ghasemi Dehnavi ,
Volume 14, Issue 5 ( English articles 2020)
Abstract
Groundwater salinization in semiarid regions is a limiting factor of use with strategic importance. In this study, the sources of salinity, chemistry, and quality of groundwater in Robat (Khorramabad plain, Iran) were identified through the geochemical methods. Using data analysis, the concentration of cations and anions were recognized with the order of Ca2+>Na+ >Mg2+>K+ and HCO3-> Cl-> SO42+> NO3-> F-, respectively. The high concentration of Na+, Cl-, and EC in some places is attributed to the gypsum and salty formations. In the study area, the salinization processes are identified by natural and artificial activities. The salinization mechanisms are identified by the natural dissolution of gypsum and salt from Gachsaran formation and man-made sources including boreholes drilled through Gachsaran Formation, salt mining, and agricultural activity. Also, the high concentration of nitrate is related to agricultural fertilizers and karstification effects. It is seen that the atmospheric NO3-. HCO3-, Ca2+, and Mg2+ concentration exceeded the standard limit in a few samples probably due to the calcareous formation. Besides, hydrochemical facies of the groundwater are Ca- HCO3 and Na-K-HCO3. Due to the presence of calcareous and salt bearing formations, 46%, 26%, and 20% of all samples show a higher concentration of Ca2+, Na+, and Mg2+, respectively, which exceed the permissible limits. Sulfate and fluoride concentrations are less than the permissible limits. However, due to the presence of calcareous formation, salt bearing formation, and use of agricultural fertilizers, 100%, 26%, and 20% of all samples show a higher concentration of HCO3-, Cl-, and NO3- than the permissible limits.
Behnaz Shahrokh, Mohsen Oftadeh, Nasrin Sohrabi,
Volume 15, Issue 2 (9-2021)
Abstract
An accurate study of the physical-chemical properties of soil has a significant effect on the determination of mechanical parameters, classification and evaluation of soils, and the civil project management aspects. The obtained accurate results of the chemical parameters of soil can determine the type and amount of cement or lime used in stabilizing the problematic soils, which leads to better estimation of sub-channel substrate consolidation behavior, accuracy in engineering designs, and so on. Previous researches showed that the chemical changes such as increasing soil solutes are one of the affecting factors on the change of the mechanical parameters of the soil [1-3]. In this study, the effect of the waves on the saturated paste and the saturation extract was presented as a novel method in order to determine the soil chemical parameters as well as the soil dispersivity potential more precisely. Also, the effect of the waves on the arid and semi-arid regions can be considered as one of the environmental parameters affecting the solubility of solutes in the saturated soil and pre estimated dispersive and semi-dispersive of the soils.
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Nasrin Zare Junaghani, Hamid Mehrnehad, Mohammad Mehdi Khabiri, Sara Srfraz,
Volume 15, Issue 2 (9-2021)
Abstract
Existence of sodium elements in fine-grained of some soils causes dispersive phenomenon in them. Failure to accurately identify dispersive clays leads to damage because dispersive clay soil particles disperse under certain conditions and wash away quickly. This research assesses dispersive degree of outcropped soils in southeast of Yazd. Finally, the modification of soil dispersive potential was investigated by using nanocellulose. After performing a series of physical, chemical and mechanical tests, characterization/ specification of the studied soils were determined. Then dispersive degree was specified by conducting chemical, pin hole, crumb and double hydrometer tests. Finally, soil dispersivity stabilization was performed using sample preparation with 0.5, 1 and 1.5% nanocellulose. The results showed that the studied soils have moderate dispersive in borehole A and extreme to slightly dispersive in borehole B. Therefore, it can be concluded that the closer we get to the center of the plain, the greater the dispersibility. The results of the dispersibility stabilization soil tests indicate that the optimum moisture content and dry specific gravity increases and decreases. Uniaxial strength and CBR increases. Also, it shows that the increase in nanocellulose has a positive effect on the modified samples and improves the soil dispersibility in this area.
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Mehdi Derakhshandi, Mojtaba Honarmand, Amir Hossein Sadeghpour,
Volume 16, Issue 1 (5-2022)
Abstract
Earth dams are geotechnical structures constructed on various shapes of a valley. The Vanyar Dam is a rock-fill dam located on a narrow valley. Concerning the geometry of the canyon, three-dimensional modeling was utilized to analyze this dam. According to the numerical analysis, the maximum settlement is 88.14 cm, which corresponds to 48 m above the bedrock in cross-section C, that is, a little less than 1% of the dam height. Besides, the total vertical stresses recorded by the pressure cells are about 28% less than those obtained from the numerical analysis. It is assumed that the difference is caused by local arching due to lower compaction and consequently a low stiffness area around the pressure cells. In terms of pore water pressure, there is good agreement between the pore water pressure obtained from the numerical analysis and the piezometers, such that the results are restricted to less than 1%. In general, the difference between the numerical analysis results and those recorded by the instruments is acceptable. Furthermore, the dam shows a suitable level of performance at the end of construction.
Maryam Mokhtari,
Volume 16, Issue 1 (5-2022)
Abstract
In geotechnical engineering, rock mechanics and engineering geology, depending on the project design, uniaxial strength and static Youngchr('39')s modulus of rocks are of vital importance. The direct determination of the aforementioned parameters in the laboratory, however, requires intact and high-quality cores and preparation of their specimens have some limitations. Moreover, performing these tests is time-consuming and costly. Therefore, in this study, it was tried to precisely predict the desirable parameters using physical characteristics and ultrasonic tests. To do so, two methods, i.e. principal components regression and support vector regression, were employed. The parameters used in modelling included density, P- wave velocity, dynamic Poisson’s ratio and porosity. Accordingly, the experimental results conducted on 115 limestone rock samples, including uniaxial compressive and ultrasonic tests, were used and the desired parameters in the modelling were extracted using the laboratory results. By means of correlation coefficient (R2), normalized mean square error (NMSE) and Mean absolute error (MAE), the developed models were validated and their accuracy were evaluated. The obtained results showed that both methods could estimate the target parameters with high accuracy. In support vector regression, Particle Swarm Optimization method was used for determining optimal values of box constraint mode and epsilon mode, and the modelling was conducted using four kernel functions, including linear, quadratic, cubic and Gaussian. Here, the quadratic kernel function yielded the best result for UCS and cubic kernel function yielded the best result for Es. In addition, comparing the results of the principal components regression and the support vector regression indicated that the latter outperformed the former.
Ali Kamali, Dr Mehdi Mokhberi, Dr Abbas Ghalandarzade,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
Marls are one of the problematic soils that undergo more erosion due to their deformability and sensitivity to humidity and weather conditions. The effects of these soils have been observed on subgrades of pavements, abutment of dams, foundation of high-rise structures, the interaction of soil-structure and etc. The strength and deformation of marls are more effective to moisture content. In addition, the dynamic parameters of theses soil are considerable as well as static geotechnical specifications. Soil dynamic parameters can be obtained from both laboratory experiments and field experiments. With the aim of understanding the dynamic behavior of marl soils, this study was carried out to evaluate the marls of northwest region of Shiraz City which is mixture of marls containing the expansive anhydride gypsum. For this purpose, the laboratory cyclic triaxial test and in situ downhole test has been performed. The results showed that for normal consolidated marls, with increasing the confined pressure from 400 to 600 kPa (increasing soil depth), the shear modulus increases from 50 to 200 kPa. In addition, the behavior of the damping ratio is relatively different for strains less than and greater than 1%, but in general, for strains higher than 1%, the damping ratio decreases from 0.21 to 0.18 with the increase confined pressure from 100 to 600 kPa.
Mehdi Talkhablou, Seyed Mahmoud Fatemi Aghda, Habibulah Heidari Renani,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
The stabilization of underground spaces is one of the most challenging topics in engineering geology. There are several methods to determine the type of tunnel stabilization system, but most of these methods have several weaknesses. Therefore, the development of a method that comprehensively considers almost all parameters influencing tunnel stability and their interdependencies has not received sufficient attention. The aim of this research is to investigate the parameters influencing the stability of tunnels using the rock mechanics system method. In this paper, 6 tunnels with different geological characteristics were selected. The effective parameters on the primary stabilization of these tunnels were coded using the ESQ method. Subsequent analyses were performed using the RES rock engineering system method to estimate and evaluate the optimal tunnel stabilization system. The results showed that parameters such as weathering of the joint surface, backfill and joint spacing played a more effective role than other parameters. For comparison, the analyses were also carried out using the RMR rock mass ranking method. The comparison between the results of the RES and RMR methods showed that the results of the RES method are in better agreement with the actual tunnel conditions and the shotcrete thickness of the proposed stabilization system of the studied tunnels. Since there is no limit to the number of input parameters in this method and, on the other hand, the mutual influence of the parameters on each other is considered, the relationships obtained from the RES method in this research can be effectively used in engineering projects along with other methods.
Dr Nasrollah Eftekhari, Dr Sasan Motaghed, Dr Lotfallah Emadali, Dr Hasi Sayyadpour,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
In the variability of earthquake hazard analysis results, ground motion prediction equations play an important role. Selection of appropriate prediction relationships for the region can lead to stability and accuracy of earthquake hazard analysis results. In this study, different prediction relationships were investigated and analyzed for earthquake hazard analysis in Ahvaz city. These relationships were ranked based on the criteria of logarithmic probability, Euclidean distance and deviation information in different periods. Then the most efficient relationships were selected by data envelopment analysis (DEA) method on the basis of differences in the obtained results. Out of 67 possible relationships, 5 were identified as suitable relationships for earthquake hazard analysis in the Ahvaz urban area. Then, a special efficiency criterion was used to determine the weight of these relationships. The results of this study can help to reduce to a large extent the uncertainties involved in analyzing the seismic hazard of the area studied.
Dr Masoud Amelsakhi, Eng Arash Ebrahimi,
Volume 16, Issue 3 (Autumn 2022)
Abstract
This research is a laboratory study to improve the geotechnical properties of fine-grained soils. For this purpose, agricultural waste ash such as sugarcane bagasse, rice husk and almond husk have been used. In this regard, the effect of using ash of the mentioned fibers with at 4, 8 and 12 weight percentages on fine grain clay soils has been investigated. The compaction test results indicate that these additives generally increase the optimum soil moisture and the maximum optimum moisture was observed for the samples made with 12% ash. Also, based on the results of the unconfined compressive strength test, the studied additives have increased the uniaxial strength of the soil. The samples made with 12% ash were the most effective, so that the addition of 12% bagasse ash increased the soil resistance by 117%, and the addition of 12% rice husk ash and almond husk ash increased the soil resistance by 89, 80% respectively.
Armin Aziminejad, Omid Makhdoom, Panan Zarfam, Abolreza Sarvghad Moghadam,
Volume 16, Issue 3 (Autumn 2022)
Abstract
In most current seismic codes, the stiffness and strength of seismic members are considered to be independent, so that a change in the strength of the members does not result in a change in the stiffness of the members. Recent studies show that these parameters are interdependent. Therefore, the way these parameters are calculated and the arrangement of centers of mass, stiffness and strength can be effective in determining the seismic response. In this research, buildings with different levels of normalized yield eccentricity (ed/A) were designed according to the ASCE/SEI 07-22 seismic code (Code Design models) and compared with the Balance-25% and Symmetric Strength models. The results of the nonlinear static analysis and incremental dynamic analysis showed that the average spectral acceleration at the level of collapse in the Balance-25% and Symmetric Strength models increased by approximately 18% compared to the Code Design model. Therefore, these models are safer than the Code Design model. In addition, the average of the peak rotation of floors and the maximum inter-story drift at the collapse level in the Balance-25% and Symmetric Strength models has decreased by 100% and 12% respectively compared to the Code Design model. Therefore, the Code Design model had the lowest and the Balance-25% and Symmetric Strength models had the highest dynamic seismic performance.
Miss Masoumeh Nikbakht, Prof Mohammad Nakhaei, Prof Ata Shakeri, Dr Vahab Amiri,
Volume 16, Issue 4 (Winter 2022)
Abstract
In this study, the hydrogeochemical and qualitative status of groundwater resources of the Zarabad coastal aquifer in southeast Iran has been investigated. The decreasing order of cations and anions is Na+>Ca2+>Mg2+>K+ and Cl->SO42->HCO3-, respectively. The two most water type are Na-Cl (78%) and Ca-Mg-Cl (22%). The water type, chlorine-alkalinity index, ion ratios, and position of the samples on the Gibbs diagram show that cation exchange (direct and reverse), weathering of silicates and evaporites, and seawater intrusion are the main controlling processes of water chemistry. The ionic ratios of SO42-/Cl-, B/Cl-, and Na+/Cl- indicate that saltwater infiltration increases as the distance from the Rabach River increases, particularly in the northwest and southeast regions. This can lead to a decrease in the quality of water resources. Moreover, the water quality for agricultural use is assessed based on some indices, including electrical conductivity (EC), sodium percentage (Na%), sodium absorption ratio (SAR), residual sodium carbonate (RSC), magnesium absorption ratio (MAR), permeability index (PI), Kelly’s ratio (KR), and USSL and Wilcox diagrams. The results showed that about 60% of the samples had unsuitable quality for irrigation. These samples were located in the northwestern and southeastern parts of the plain. About 40% of the samples have suitable quality for irrigation and are located in the vicinity of the Rabach River.
Dr. Davood Fereidooni, Dr. Sajeddin Mousavi, Dr. Esmaeil Najafi, Dr. Gholam Reza Khanlari,
Volume 16, Issue 4 (Winter 2022)
Abstract
Assessing and understanding the hydromorphological characteristics are necessary to understand the behavior of a river and its active processes. This is useful for understanding the erosion and sedimentation regime and changing the river path, for making correct engineering and human activities in the river's catchment area. The Gian River, with an average annual discharge of 2.3 m3/s, is one of the tributaries of the Gamasiab River in the Hamedan province. From a geological and hydrogeomorphological point of view, the Gian is a small river. It is fully compatible with the geological structures of the region. The calculation of the sinusoidal coefficient has shown that this river is a meandering river whose wavelength, the amplitude of the oscillation and the width of the meander belt are smaller in the mountainous area than in the plain area The gradient of the river bed is relatively low and it is classified as an erosion and sedimentation river in its different sections. The Gian River has a rocky bed in the mountainous part and an alluvial bed in the plain. The Gian River has a small catchment area, and, according to theGravelius' coefficient, its shape is almost elongated. The catchment elevation of the Gian River is between 1455 and 2700 with a weighted average of 1715.20 m.a.s.l. and its area decreases with the increase in the elevation. The concentration time of the catchment is 4.204 hours. The application of the data and results of the research can be very effective in land use planning, engineering and executive applications to predict river changes and protect engineering structures such as roads, bridges, coastal structures and railways, protect agricultural lands in the region and develop tourism.
Khadijeh Kord, Heeva Elmizadeh, Hakimeh Amanipour,
Volume 17, Issue 1 (Spring 2023 2023)
Abstract
The study area is a part of the Dez River Basin, which is located in the central part of the basin. In this area, due to the climatic conditions, the irregular availability in terms of time and space, the increasing use of water resources and surface water resources, there is a great dependence on the underground water of the region. The main objective of this research is to investigate the factors influencing the fluctuations of the water level in the Dezful-Andimeshk plain during a statistical period of 20 years. For this purpose, using piezometric well level data and well logs of the study area in WinLog software, maps of the groundwater level and the bottom level of reservoir were prepared using theIDW method. The results of the research showed that the greatest drawdown occurred in north-eastern, south-eastern and western parts of the study area. Asthe amount of precipitation, evaporation and temperature are high in this part, one of the reasons for the decline in these parts can be attributed to the climatic factors of the region. Other factors in the decline of the reservoir level are the main river channel and the high slope of the area. Comparing the changes in the reservoir level with the flow of the Dez River showed that there is a high correlation between the changes in these two parameters with a time interval of one year. Therefore, according to agricultural activities, these limited resources should be harvested, scientifically and fundamentally, the region will be at risk of a serious water crisis in the future.
- Fatemeh Khalooei, - Heeva Elmizadeh,
Volume 17, Issue 2 (Summer 2023)
Abstract
In this study, images from the Sentile 2 satellite have been used. In the study, the proximity of the images was taken into account to minimize the error due to changes in gray scale. Also in this study, GIS and remote sensing data and SNAP software were used as tools.According to the subsidence zones obtained in the study area, it is observed that the maximum amount of subsidence around the tomb of Sheikh Mohammad is between 80-90 mm per year of landslide. The results show that the highest rate of subsidence in the study area is due to agricultural use and irrigated agriculture in the region. This problem may be mainly related to the issue of groundwater extraction for agriculture and drinking, and possibly other factors such as geology and tectonics. The centralization of the maximum rate of subsidence in residential areas has led to relatively insecure living conditions for the inhabitants and increased their vulnerability to land hazards. Also, considering the results of the steps taken to study the phenomenon of land subsidence in the study area, it is concluded that the phenomenon of land subsidence has a significant relationship with the grain size and with the lowering of the water table. Therefore, the combination of radar interference methods with high spatial resolution with high spatial resolution, satellite positioning systems with high temporal satellite positioning systems with high temporal resolution, and precise alignment with very high accuracy, is a good way of to study the movement of the earth's surface.
Mister Hamzeh Torkamanitombeki, The Doctor Mashalah Khamehchiyan, Mistress Maryam Nazari, Mister Shazdi Safari,
Volume 17, Issue 3 (Autumn 2023)
Abstract
The purpose of the research is to investigate the risk of liquefaction risk at the beaches of Bustano in the western part of Bandar Abbas in Hormozgan province. The periodic stress method was used as the method to evaluate the liquefaction potential based on the data obtained from Standard Penetration Test (SPT). The acceleration of 0.35 g was chosen as the maximum acceleration of the bedrock, and cross sections were extracted using Rockwork software. From an engineering geological point of view, the characteristics of the sedimentary deposits and the collected geotechnical information were analyzed to generate geotechnical index profiles. As the study area is located at the edge of the folded Zagros, seismically it has the characteristics of the Zagros-Makran transition zone which basically exerts the most pressure on the saturated sediments of the area. Due to the strong movement of the earth in generating liquefaction, the seismic bedrock acceleration (PGA) and the maximum horizontal acceleration at the ground surface (amax) were evaluated by liquefaction analysis using LiqIT v.4.70 software. The results indicate that the sandy and silty sediments of the study area are the outcome of the weather changing processes at the northern altitudes of the region. Granular sand and silt sediments were found under favorable conditions with high groundwater level, confirming the presence of liquefaction phenomenon in the area. Zoning maps of the intensity of liquefaction were extracted at the surface and at depth were obtained in different parts of the Bustano, indicating the different classes of risk of liquefaction in the soil of this area. In general, the occurrence of liquefaction with high intensity liquefaction was predicted for the Bustano area.
Khandani, Atapour, Yousefi Rad, Khosh,
Volume 17, Issue 3 (Autumn 2023)
Abstract
Backfill materials used to fill underground mines are a type of engineered material whose particle size distribution (PSD) directly affects their mechanical and physical properties. According to the authors' review, there is no comprehensive standard for the properties of aggregates used in underground mine backfill materials. In this paper, the particle size ranges and particle size distribution curves of various mine backfill materials, including hydraulic backfill, paste backfill and rock backfill, have been reviewed. The available data on different types of backfill materials were collected. Based on the collected data, the smallest particle size, the largest particle size and the PSD curve ranges for each type of backfill material were determined. Then the characteristics of the particle size distribution curve of each backfill material, including the mean particle diameter (D50), the uniformity coefficient (Cu) and the curvature coefficient (Cc), were calculated. The results of the analysis of the PSD curves for paste backfill, hydraulic backfill and rock backfill materials showed that the particles in rock backfill and paste backfill had the largest and smallest sizes, respectively. Finally, the particle size distribution characteristics of a new backfill material prepared from construction and demolition waste (CDW backfill) are presented and compared with the particle size distribution of each of the conventional backfill materials. The results indicate that the PSD curve of the CDW backfill lies at the upper limit of the range of the particle size distribution curve of hydraulic backfill and at the lower limit of the range of the particle size distribution curve of rock backfill.
Prof. Mohammad Nakhaei, Dr. Amin Mohebbi Tafreshi, Dr. Tofigh Saadi,
Volume 17, Issue 4 (Winter 2023)
Abstract
A sharp drop in groundwater level as a result of indiscriminate extraction over a long period of time leads to the drying up of groundwater flows, which is called the phenomenon of groundwater drought. In this regard, this research aims to investigate the process of change and reduction of groundwater level, which is characterised by the phenomenon of groundwater drought. Based on this, the Groundwater Resource Index (GRI) was used to evaluate the drought condition of groundwater and analyse its spatial and temporal patterns based on groundwater level data of 21 observation wells between 1993 and 2019. ArcGIS software was used to create zone maps. The results of the research show that certain areas of the study area have experienced moderate to severe drought since 2001. In addition, the GRI zonation maps show that the southern and south-eastern regions of the aquifer have been more sensitive to drought than other parts of the aquifer during the defined period. The spatio-temporal pattern of groundwater drought in the aquifer shows that after a period of moderate drought from 2001 to 2003, the condition of the aquifer improved slightly, and generally stable conditions were established from 2001 to 2010, but since 2011, the occurrence of drought has intensified and the aquifer has been in severe to very severe drought conditions. These conditions highlight the need for careful attention and implementation of management measures. One of the study's recommendations is to use satellite data on groundwater levels to assess the progress of the drought, and compare it with the findings of this study.
Dr Masoud Amelsakhi, Eng Elham Tehrani,
Volume 17, Issue 4 (Winter 2023)
Abstract
This research is a laboratory study to improve the geotechnical properties of sandy soils. Concrete waste with a grain size of 1.2 to 1 inch was used for this purpose. The effect of using concrete waste at 0, 10, 20 and 30 weight percent on dry sandy soil in two loose and dense states was investigated. Based on the results of the direct cutting test, the addition of concrete waste has increased the shear strength and the internal friction angle of the soil; The loose samples made with ٪30 of concrete waste had the greatest effect, so adding ٪30 of concrete waste to loose sand increased the internal friction angle of the soil by ٪32 and the shear strength by ٪42 Similarly, adding ٪10 of concrete waste to dense sand increased the internal angle of friction of the soil by ٪4 and the shear strength by ٪6.
Eng. Zahra Soleimani, Dr. Ebrahim Rahimi, Dr. Houshang Khairy,
Volume 18, Issue 1 (Spring 2024)
Abstract
This article deals with the strength evaluation of concrete obtained by adding different percentages of three types of nanominerals, including nanocalcite, nanobarite and nanofluorite. To measure the velocity of ultrasonic waves and compressive strength of concrete, 15×15×15 cm cube samples were prepared with 7-, 28- and 90-days curing. 10 types of mix designs with 0.39 water-cement ratio, including the control sample (without additives) and the samples with 0.5, 0.75 and 1% nanominerals were subjected to the mentioned tests. The results showed that the addition of nanocalcite, nanofluorite, and nanobarite with values of 0.75%, 1%, and 0.75%, respectively, have the highest compressive strength compared to the control sample. Although these do not have pozzolanic properties, they play a positive role in increasing the concrete strength by filling concrete voids and due to their high specific gravity, increasing concrete density.
