Showing 154 results for gh
Hossein Mohammadzadeh, Vahid Naseri Hesar, Hamid Ghalibaf Mohammadabadi,
Volume 17, Issue 4 (Winter 2023)
Abstract
Due to the complex hydrogeology of karst areas, the sealing of dams in such areas is more difficult, time-consuming and expensive, and the possibility of water leaksge is higher. After the dewatering of the Gharetikan dam and appearance of downstream springs and the leakage of water from the abutment of the Tirgan limestone formation, the possibility of karst development is considered to be the most important problem of this dam. In this article, the potential of karst development in the area and supports of the Gharetikan Dam has been studied by carrying out geological studies, structural geology and joint studies, geotechnical permeability and analysis hierarchy method (AHP).. The results show that about 14.6% of the Gharetikan dam area has a high potential for karst development. The area of Gharetikan dam area is affected by the Sarroud fault zone system, which has caused the collapse of the left side of the dam axis. The joint studies in the abutment of Gharetikan dam show three main types of joints. Two groups of joints are located at the intersection with the dam axis and the slope of the other group of joints is towards the dam basin. The investigating of Lugeon permeability tests in the dam construction shows that the highest permeability can be seen in the left abutment with turbulent flow, and then under the river bed with linear and turbulent flow, but there is no permeability in the right abutment. And the flow is mostly linear. According to the structural-conceptual model prepared from the location of the Gharetikan dam, to the location of the dam axis in the Sarroud fault system, and the amount opening and the slope direction of the joints in each station, it is expected that the amount of water leakage and escape and the possibility of karst development from the left side and the bed of the dam will be more than the right side of the dam.
Dr Seyed Yahya Mirzaee, Phd Student Roghayeh Amiri, Dr Manouchehr Chitsazan,
Volume 17, Issue 4 (Winter 2023)
Abstract
This study investigates the effects of climate change on the Khorramabad Central Plain aquifer. The climatic variables of temperature and precipitation were studied and downscale using GCM and LARS-WG models for a 45-year base period (October 1971 to September 2015). Temperature and precipitation values were then projected for a 30-year period (October 2024 to September 2054) under the climate scenarios SSP1.2.6, SSP2.4.5 and SSP5.8.5. The rainfall runoff simulation was carried out in the Khorramabad basin using the IHACRES model. The groundwater flow in the central plain of Khorramabad was calibrated using MODFLOW code for a period of 120 months (October 2010 to September 2020). This model was validated for a period of 36 months (October 2020 to September 2023). According to the results, the values of precipitation in the future period compared to the base period will decrease by 42.6, 47 and 61.9 mm in the scenarios SSP1.2.6, SSP2.4.5 and SSP5.8.5 respectively. The annual mean of minimum and maximum temperatures increases in all three scenarios. After calibration of the IHACRES model, NSE=0.74, RMSE=1.46 and R2=0.64 were obtained. According to the results, the predicted discharge of the Khorramabad River in the future period will increase by 2.38 m3.sec in the SSP1.2.6 scenario and decrease by 0.42 and 0.94 m3.sec in the SSP2.4.5 and SSP5.8.5 scenarios, respectively, compared to the base period. The average 30-year aquifer balance under the SSP1.2.6, SSP2.4.5 and SSP5.8.5 scenarios was 27494.5, -12335.3 and -41823.3 m3, respectively. The groundwater level of the Khorramabad Central Plain aquifer will decrease in the future period.
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 Sayed Ali Asghari Pari,
Volume 18, Issue 1 (Spring 2024)
Abstract
Pile design is subject to a number of uncertainties that must be addressed to ensure the reliability and safety of the foundation. A common approach to reduce uncertainties in pile design is to calibrate the resistance factor in the Load and Resistance Factor Design (LRFD) method through reliability analysis. However, it is important to recognize that the LRFD method may not fully account for uncertainties associated with soil and pile resistances. The results of this study show that the separate consideration of base and wave resistance can lead to a more accurate and reliable design of piles. The proposed method can help engineers make more informed decisions and reduce uncertainties in pile design. In addition, the study highlights the importance of considering different factors such as the ratio of dead to live load and the ratio of base to shaft resistance when calculating the resistance factor.
Amin Ahmadi, Maryam Zebarjad, Ghoramreza Mirzavand,
Volume 18, Issue 1 (Spring 2024)
Abstract
The zone of influence is the area where water withdrawal from the well causes the water level to fall. The drawdown cone is a conical shape of the water level in the zone of influence, and it is necessary to know the effect of the factors influencing it. Previous studies have mainly investigated aquifers with horizontal water levels and less realistic conditions. The purpose of this study is to investigate the effect of well physical parameters on the drawdown cone in one of the unconfined aquifers with a sloping water surface. In this aquifer, a normal discharge well was simulated using the Modflow program and the effect of the target parameters was studied. The results showed that: the drawdown cone is symmetrical up to long pumping and relatively long distances; the zone of influence will eventually extend to the entire aquifer and significant drawdown will occur at long distances. A significant part of the drawdown in the well is recovered in the first moments of pump shutdown, but at long distances, the drawdown continues to increase for a long time. An inflection point can be extracted from the drawdown cone which represents the minimum drawdown that does not increase after the pump is stopped and can be introduced as a unique value. By increasing the flow several times, the depth of the cone increases, but the width of the cone increases only slightly. If the pump is turned on and off successively, the general shape of the cone does not depend on the nominal discharge of the well, but mainly on the average discharge of the aquifer. Relative infiltration increases the depth of the cone only near the well and has no significant effect on its shape further away.
Somayeh Zarei Doudeji, Rahim Bagheri, Hadi Jafari,
Volume 18, Issue 1 (Spring 2024)
Abstract
Groundwater resources in Iran are of particular importance due to the lack of surface water resources, lack of precipitation, high evaporation volume and recent droughts. The first step in identifying and exploiting groundwater resources is its quantitative and qualitative investigation. Neyriz watershed, located in the study area of Qatroiye desert, has 17 piezometers, whose groundwater level has been recorded monthly during the statistical period of more than 12 years. Investigations of the groundwater level and the map of the flow lines show the anomaly of the flow in the south and southwest part of the aquifer, which shows the direction of the groundwater flow contrary to the direction of the topography of the area. In this research, an attempt was made to investigate the cause of this anomaly based on the available information, including piezometer drilling logs, aquifer quality data, and national statistical data. Based on the qualitative information of the aquifer, the electrical conductivity and chlorine values of the groundwater increase in the direction of the topographic slope, which indicates the flow in the direction of the topographic slope. Qualitative charts of Piper, Schuler and Durov also confirm this issue. The level of groundwater in selected exploitation wells for qualitative sampling based on the information of the depth of groundwater in national statistics also indicates the flow in the direction of the topographic slope. Finally, a clay layer with a thickness of 10 to 30 meters was observed in the drilling log of the piezometers in the south and southwest of the aquifer. Examining all the results shows that the existing aquifer is probably a double-layered aquifer, where the flow direction in the upper layer is in the direction of the topographic slope and in the lower layer is against it, and the piezometers of the south and southwest parts penetrated the lower aquifer. In order to confirm the desired hypothesis, it is suggested to carry out geophysical studies in the area or to dig exploratory wells.
Ms Roghayeh Hasani, Dr Ebrahim Asghari-Kaljahi, Dr Sina Majidiana,
Volume 18, Issue 2 (Summer 2024)
Abstract
With the expansion of the petroleum industry and the aging of facilities and pipelines, oil spills are becoming more frequent. In addition to environmental impacts, oil spills can cause changes in the plasticity and dispersivity of soils. To investigate the potential for dispersion in fine-grained soils due to oil leakage, soil samples were collected from the Shazand Refinery area in Arak and mixed with 0, 5, 10, 15, and 20% by weight crude oil. Specimens were prepared at the maximum dry density obtained from the Proctor compaction test and, after curing, pinhole and double hydrometer tests were conducted. The results of the mentioned tests showed that the fine-grained soil tends to disperse with the addition of up to 15% oil, and this dispersion increases with further increases to 20%. Changes in the soil fabric with increasing oil content were investigated using scanning electron microscopy (SEM) images, and the results showed that the dispersion of soil particles increased with increasing oil content.
Seyyed Mahmoud Fatemi Aghda, Seyyed Sara Mousavi Herati, Mehdi Talkhablo, Amir Maziar Raeis Ghasemi,
Volume 18, Issue 2 (Summer 2024)
Abstract
The alkali-silica reaction of aggregates is one of the most significant factors in the destruction of concrete structures worldwide. This is due to chemical reactions between alkaline fluids in concrete voids and active silica minerals present in some aggregates. Considering that many physical, chemical and mechanical properties of concrete are related to aggregates, the role of aggregates in concrete is crucial. This research aims to investigate the compatibility of aggregate petrographic studies and accelerated prismatic mortar testing in predicting the reactivity of aggregates and determining the intensity of aggregate reactivity using the DRI index (a semi-quantitative complementary petrographic analysis). The study was carried out on laboratory samples of aggregates from mines around Tehran, using the ASTM C295, ASTM C1260 and ASTM C856-4 tests. The results showed that pyroclastic aggregates, which include sandy tuff, crystalline tuff (dacitic andesite) and glassy tuff, have the potential to cause an alkali-silica reaction due to their glassy background and microcrystalline silica. During the alkaline reaction tests of the aggregates, evidence of gel was found in cracks, holes and cement paste. In addition, the DRI index showed that the fine aggregates of both study areas were in the "slightly damaged" category and the coarse aggregates were in the "severely damaged" category.
Somayeh Zarei Doudeji, Rahim Bagheri, Hadi Jafari,
Volume 18, Issue 2 (Summer 2024)
Abstract
Due to Iran's weather conditions and lack of water resources, dam construction projects are particularly important for the country's development and progress. Water resources management based on system dynamics is capable of simulating complex water resources systems. This model for the simulation of water resources has various capabilities, such as increasing the speed of model development, the possibility of group development of the model, effective communication of the results, and increasing confidence in the model through user participation. In this research, the model of the dynamic system of the multipurpose dam of Qamshek in Hormozgan province has been simulated using the probabilistic simulation method. The purpose of this modelling is to realize different needs of the dam (domestic, environmental, industrial and agricultural) before its construction and to check the quality conditions of the reservoir. The study of the results of the quantitative modelling was done after calculating the annual and monthly percentage of volumetric and temporal supply of different needs and their source of supply. The results show that the volumetric supply percentage of domestic, environmental, industrial and agricultural needs of the dam is 95.53, 95.02, 94.18 and 93.14% respectively, and the temporal supply percentage of domestic, environmental, industrial and agricultural needs is 95.19, 94.94, 93.67 and 92.91% respectively, which are all within the acceptable range of the Ministry of Energy. Qualitative modelling of the dam was carried out for the most pessimistic case with a discharge electrical conductivity of 3000 and a base discharge of 10000 micromos/cm, on the basis of which the maximum electrical conductivity of the reservoir was calculated to be 11900 micromos/cm. Based on this research, it was found that by modelling based on model evaluation indicators, including percentage of volume supply and percentage of time supply of different needs, it is easy to quantify the effect of exploitation and management policies on the way of determination and allocation. Observed the quality of water resources and made the most optimal decision.
Dr Mehran Esfahanizadeha, Dr Mohamad Davoodi, Dr Ebrahim Haghshenas, Dr Mohamad Kazem Jafari,
Volume 18, Issue 2 (Summer 2024)
Abstract
The determination ofgeological subsurface strata and shear wave velocity profiles is one of the most important engineering measures for seismic design and site effects studies. Recently, the use of seismic geophysical methods in engineering geological studies for this purpose has become widespread. In this paper, the accuracy and efficiency of seismic geophysical methods with active and passive seismic source in determining the subsurface geological structure of a selected site in the city of Abasabad in northern Iran have been studied. To this end, first, by conducting several exploratory boreholes, the subsurface geological structure of the study site up to a depth of 70 meters was carefully determined using engineering geological experiments. The results of this section showed that the shallow sediments of Abasabad site are mainly composed of sandy soils with four separate geological layers. In the next step, in two other separate boreholes, seismic geophysical experiments with active source of down-hole test were performed in order to accurately determine the shear wave velocity profile in different layers. In addition, in the next phase, using the array microtremor recording method, which is a new seismic geophysical method of passive-source type, to determine the subsurface geological structure of the study site in the form of shear wave velocity profiles. It should be noted that the array microtremor recording was performed using fifteen different arrangements of receptors (with different numbers and distances of receptors) and by two analyzing methods including F-K and SPAC. The results of these studies showed that both active and passive seismic geophysical methods had acceptable performance in determining the subsurface geological stratification of the site. It also could be inferred that the down-hole test with high accuracy determines the shear wave velocity in each layer compared to the array microtremor method but requires artificial production of seismic waves and borehole drilling. Array microtremor method without the need for drilling and production of artificial seismic waves has high efficiency in determining the subsurface layering and estimating the shear wave velocity of each layer and in general the results of this paper showed that in estimating the shear wave velocity compared to down-hole method shows up to 10% error.
Zahra Aghayan, Rouzbeh Dabiri,
Volume 18, Issue 3 (Autumn 2024)
Abstract
Recently, the demand for rapid and cost-effective infrastructure development has led to the has led to the development of various soil improvement techniques, including stabilization. Studies on the incorporation of mineral materials such as lime and coal ash into soil stabilization have been carried out in several countries, and these studies have shown promising results. Given the beneficial properties or properties of coal ash, together with its availability and cost-effectiveness, the combination of coal ash with lime for clay soil stabilization is a viable option. This study evaluates lime and coal ash on the behavior and geotechnical properties of clay soils. The evaluation includes plasticity index (PI), compaction, uniaxial compressive strength, California bearing ratio (CBR) and direct shear tests, and direct shear tests. To achieve this, the process began with the mixing of clay with varying percentages of hydrated lime (4%, 6% and 7%), followed by a 28-day curing period for the samples. Coal ash was then added at different (5%, 15%, 25% and 50%) was incorporated into the clay and also cured for 28 days. In the final stage, the optimum amount of hydrated lime was determined, an amount of hydrated lime, equivalent to the amount of coal ash used, was added to the clay and the mixture was cured for a further 28 days. The results indicate that A mixture of 7% hydrated lime and 50% coal ash, after 28 days of curing, is an optimum combination for stabilizing the clay in the study area. This combination increased the uniaxial compressive strength by 1.87 times, the shear strength by 1.34 times and the CBR value by 6.4 times, making it suitable for use in the for use in the construction of pavement layers.
Dr Sasan Motaghed, Dr Marzieh Shamsizadeh, Dr Nasrolla Eftekhari,
Volume 18, Issue 3 (Autumn 2024)
Abstract
In this study, we present the Seismic Hazard Possibility Space (SHPS) for the city of Ahvaz. To achieve this, we applied the intuitionistic fuzzy method to weigh the logic tree used in the hazard analysis and constructed the SHPS based on expert opinions regarding the degrees of membership and non-membership. Hazard disaggregation was performed by through the concept of intuitionistic fuzzy sets, leading to the development of an intuitionistic fuzzy of an Intuitionistic Fuzzy Logic Tree (IFLT). The SHPS includes both the degree of membership and non-membership for pathways contributing to hazard generation. The SHPS illustrates the acceptance, non-acceptance, and ambiguity associated with potential hazard values from an expert perspective, thus assisting analysts in selecting appropriate hazard values. According to the numerical results of our analysis in the Ahvaz region, the seismic hazard is located in an uncertainty (unacceptability) zone, indicating that experts have low confidence in the results of the probabilistic seismic hazard analysis (PSHA) for Ahvaz. In addition, the hazard is characterized by an "unconfident zone". This finding indicates that experts are fairly confident in the results of the analysis for Ahvaz. This finding implies that the models and parameters used in the PSHA for this region are not accepted by experts, and further efforts are needed to identify or develop appropriate models and accurate parameters specific to the area. In conclusion, this research demonstrates how intuitionistic fuzzy sets can be used to construct SHPS, providing a novel framework for quantifying uncertainty and expert opinion in hazard assessment.
Shaghayegh Samiee-Rad, Giti Forghani, Hadi Jafari,
Volume 18, Issue 3 (Autumn 2024)
Abstract
The Garmabdasht River as the first tributary of the Qarasu River, flows through the city of Gorgan and eventually flows into Gorgan Bay. In order to study the hydrochemistry and to assess the water quality, 10 water samples were collected in June 2022. Physicochemical properties (pH, electrical conductivity, total dissolved solids), major ion concentrations, and microbiological parameters (dissolved oxygen content, biological oxygen demand, chemical oxygen demand, and coliform bacteria) were measured by standard methods. The obtained results show that the pH of the water samples varies between 7.5 and 8.5 and the electrical conductivity of water samples varied between 376 and 665 µs/cm. In terms of hardness, water samples were classified as hard and very hard. The concentrations of the major ions, phosphate and nitrate were within the permissible range for drinking usage. By calculating the ionic ratios and drawing the Durov diagram, it was found that the water chemistry was mainly controlled by the dissolution process. The position of the samples on the Piper diagram shows that the type and facies of the river water samples were calcium bicarbonate, magnesium bicarbonate and calcium sulphate. According to the Wilcox diagram, the Garmabdasht river water was suitable for irrigation. The residual sodium carbonate and sodium percentage values confirm this conclusion; however, based on the magnesium hazard index, the studied samples were not suitable for irrigation. The values of dissolved oxygen in all samples were within the permissible limit. The amounts of biological oxygen demand and chemical oxygen demand in some stations exceeded the permissible limit due to the influx of livestock and agricultural effluents. The obtained results show that the samples were microbially polluted, which may induce the health problem in the local population. The values of NSFWQI also shows that, except for the upstream samples of S1 and S2, the quality of the studied samples for drinking is in the bad to medium class.
Mr. Ehsan Pegah, Mr. Behrang Feiz Aghaei,
Volume 18, Issue 3 (Autumn 2024)
Abstract
Random noise reduction has always been one of the most important issues in seismic data processing. This study investigates one of the most effective random noise reduction methods, the 2D multi-stage median filter. This filter is applied to seismic data by applying a series of 1D median filters in different directions and then selecting the output value corresponding to the center of the 2D window. By applying a 2D multi-stage median filter to both synthetic and real data, it is shown that the filter can effectively attenuate random spike-like noise in both pre-stack and post-stack data. Similarly, based on spectral analysis, it is shown that this filter does a good job of reducing the level of high frequency random noise in both synthetic and real data. In this study, a 2D median filter is applied to synthetic data containing random noise with a density of 10%. Since increasing the filter length can damage useful signals in addition to attenuating random noise, it is important to specify an appropriate filter length. For synthetic data, the error ratio plot shows that a filter length of 9 points is appropriate for the first stage. In the second stage, a 2D median filter with a length of 7 points was applied to the output of the first stage filter. The effect of this filter on random noise suppression can then be observed by spectral analysis. In addition, median filters of 7 points and 5 points were applied to the pre-stack and post-stack real data, respectively. The effect and efficiency of this filter is assessed by examining the resulting difference plots, sections and spectral analysis.
