Journal of Engineering Geology

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Gotvand dam reservoir with over 90 km length is surrounded by Gachsaran, Mishan, Aghajari and Bakhtiari formations. The noticeable point in the dam reservoir is the presence of Gachsaran Formation that is composed of considerable volume of salt located  4 km upstream of dam. Salinity of dam water due to dissolution of salt in reservoir water can cause serious environmental problems. In addition to direct dissolution of salt in contact with reservoir water, slope instability can also influence on this process. Probable sliding in salty layers of slopes will insert a significant volume of salt in contact with reservoir water in a short time. In order to study the land-sliding process in reservoir area and also analysis of the effect of dissolution of salty layers on sliding, characteristics of dominant material engineering of mass constituent were defined by rock mechanics experiments. Then the results of performed tests on rock samples and GSI method were used to estimate the engineering parameters of rock mass. To investigate the land-sliding process in reservoir area and also the effect of dissolution of salty layers on sliding, some salt samples were transferred to the laboratory. Using circulation method, solubility of those samples were examined in different conditions. The results were generalized to the reservoir condition. Eventually, slope stability were analyzed by modeling with SLIDE software, considering different levels of reservoir water, influence of dissolution of salty layers. The obtained results indicate that slidings in reservoir area are mostly shallow and are caused by dissolution of salty layer.

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Today, one of the most problems, for the purpose of flood management is river flow prediction. Prevention of economic body suffering arise of flood is one of the most important achievements of correct flow prediction. Factors and divers parameters influence the discharge, make complex the analysis. Conception-physical model, regression models and time series are the most common- analytical approach of river flow. In this search by using of discharge data of Ghareh Ghanlo station in 13 years ago, the prediction of Sombar river discharge by Box-Jenkins was done. To do so, MINITAB software was used. Also for selecting of the best prediction model used of error evaluation factor and ARIMA (1,1,0) (2,1,1)12 was selected as the best prediction model and finally by use of these methods river discharge for 24 next month, was forecasted. 

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Slake durability of rocks is an important engineering parameter for evaluating deterioration of rocks in chemical and physical agents that are related to mechanical properties of rock. The main purpose of this study is to assess the influence of the number of drying and wetting cycles under variable pH conditions and controls of mineralogical composition on durability. For this purpose, five different types of tuff were selected from different parts in north Qazvin city. The samples were subjected to multiple-cycle slake durability testing with different pH values solution. Also the slake durability tests in saturated condition on samples, petrographical analyses and basic physical - mechanical test were performed. In addition, to assess the influence of mineralogical composition on durability, the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after fifteen cycles were also determined by XRD analyses. It was concluded that the slake durability of tuff is independent of the pH in acidic solution circumstances. Mineralogical composition, fabric and weathering rate are considered to have a greater influence on the slake durability of tuff. A strong relationship between the point load strength and the fifteenth-cycle slake durability index is found in the rock types studied.

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In this paper, a constitutive model is proposed for prediction of the shear behavior of a gravely sand cemented with different cement types. The model is based on combining stress-strain behavior of uncemented soil and cemented bonds using deformation consistency and energy equilibrium equations. Cement content and cement type are considered in a model as two main parameters. Based on the proposed method, the behavior of cemented soil with different cement types is predicted for conventional triaxial test condition. Porepressure developed during undrained loading besides volumetric strains in drained condition are also modeled according to this framework. Comparison of model results with experimental data indicates its reasonable accuracy.

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One of the geotechnical hazards in the tunnels under high overburden and high in situ stresses is the phenomenon of rock burst. Rock burst is a typical geologic phenomenon caused by excavation in rock masses. In this phenomenon, because of stress released and explosion in rock masses, they are broken as large and small pieces and are distributed, so that leads to damage of peoples or equipments. Therefore, familiar with this phenomenon and its mechanism of occurrence, is need to analyze this issue. The second part of water supply Karaj-Tehran tunnel with a length of 14 km and about 4.5 m diameter is located in Tehran province. Rock burst analysis has been carried out in the tunnel from kilometer 6 to 9.5 that is critical section because of high overburden (up to 800 m) and presence of faults and crushed zones. In this paper, for predicting rock burst in the critical section of second part of Karaj-Tehran tunnel, four criteria including, Strain energy, Rock brittleness, Seismic energy and Tangential stress criterion are used. Analysis results show that units with high overburden have high possibility of rock burst. 

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In this study using finite element procedure was used to simulate the dynamic behavior of reinforced soil walls, to evaluate their dynamic response on all types of deformation modes, different mechanisms of failure detection and identification of parameters in each of the modes and the mechanisms. Detailed numerical modeling, behavioral models and materials were described and Dynamic response of the physical model has been validated experimentally. Parametric study has been of the wall height of 5 meters by the effective parameters such as hardness, length to height ratio, the vertical reinforcement, wall height, and acceleration inputs. Three modes of deformation were observed. The study showed that occur bulging deformation mode while the use of flexible reinforcement and occur overturning deformation mode while the use of stiffness reinforcement. Stiffness reinforcements have the most effective in changing the type of deformation. Length to height ratio of reinforcements has the minimum effective in changing the type of deformation.

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Awareness of orphological features of rivers is necessary for recognition of river behavior and optimum application of rivers. Overall catchment physiografy have important role for determination factors such as floods, erodible and sediment mutagenicity. In this study in order to understand the behavior of Gamasiab River in the east of Kermanshah province, geomorphologic features of this river has been considered. Study of engineering geomorphologic properties is done by using existing data from previous studies, site visit and field perceptions, study of geology and topography maps. Physiographic properties of catchment, channels morphologic properties and geology conditions in this region have been studied. In this research, several parameters such as average width, environment, area, hydrogeologic coefficient, catchment form, maximum, minimum and mean high, and longitudinal slope has calculated. Also status of drainage density of this river has been investigated and time to focus calculated. Finally this river review and classified according to various classifications for rivers

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River bank erosion is a mechanism initiated by soil particles movement due to subsurface flow. This may occur in a soil texture at a critical hydraulic gradient. With regard to the complexity of river bank erosion processes and limited research in this field, it is of significance to investigate and to identify the effective parameters. In the present study, a physical model of a river bank was developed to achieve in-depth understanding of the effects of bank material particle sizes on porous media under various hydraulic gradients. It is concluded that the length of scour hole caused by seepage erosion may depend on the hydraulic gradients as well as Reynolds number. Further, two empirical relationships are derived on the basis of observed experimental results to estimate scour hole length resulted from river bank erosion for laminar and turbulent conditions

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In the recent years there was a great improvement in the development of underground structures. Due to the increase in the costs of constructions and the importance of the safety in transportation, attention has been focused on the hazards of earthquakes. In this paper, the effect of earthquakes and the importance of seismic analysis are described. The analysis method is presented briefly, and then the simplified analysis of Hashash et al. (2001) is used. Two metro station structures under two different seismic hazardlevels were analyzed. Pushover analysis method is also used which is a simple and static non-linear method in seismic analysis and design of structures.  In this non-linear analysis, the target displacement is computed by the simplified frame analysis model. The finding of this study showed that the structure behavior was remained elastically to a large extent of displacement using this method. Hence, the design of the structures based on the performance level or reduction of the moment extracted from the Hashash et al. (2001) method is recommended.

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Comprehensive laboratory tests were performed to assess fatigue behavior of Alvand monzogranite rock subjected to uniaxial cyclic loading. A series of static loading tests was done to obtain the required data for the fatigue tests. Three maximum load levels (85, 90, 95% uniaxial compressive strength (&sigmac)) at amplitudes 70% were used with 1Hz cyclic loading frequency. The results indicated that maximum stress level significantly influenced fatigue behavior of this rock. It was found that fatigue life decreases in a power function with increasing maximum stress level. Accumulative fatigue damage process shows three stages of behavior including crack initiation phase, uniform velocity phase and acceleration phase. Fatigue damage process were analyzed according to axial and lateral maximum and minimum strain, tangent and second modulus, toughness and hysteresis energy in both loading and unloading conditions. Among these parameters, lateral strain, axial strain and second modulus show the best three-stage fatigue damage behavior. Also, it should be noted that most of the cracks generated in parallel to loading direction and lateral strain are affected by more than axial strain.  

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One of the most important issues in the design and implementation of engineering structures is to evaluate and investigate their durability against processes of consecutive wear, wet and dry. The durability of rock is resistance against chemical and physical weathering, the shape, size and status of the initial appearance in a long time and environmental conditions prevailing in the rock, hence it is important to evaluate the durability of rock. Since the device of standard durability (Franklin & Chandra, 1972) designed to evaluate and investigate durability of soft and argillites rocks. So, appears to be essential to design a durability device, which can evaluate hard rocks. For this purpose, Researchers of the Department of Geological Engineering, Tarbiat Modares University, durability device as "large-scale durability device " was designed and built which the length and diameter of the device, is 6 and 4.3 times standard durability device, respectively, and needs 10 samples with weight of 400 to 600 g. In order to investigation the applicability of this device for hard rocks durability, we selected 17 building rocks samples of the igneous, sedimentary, metamorphic and pyroclastic rocks. Then their mineralogical, physical and mechanical properties were investigated. More, experiments of standard and large-scale durability up to 15 cycles were performed and data obtained were analyzed. The results show that, the large-scale durability device than standard durability, have more applicability for evaluating the durability of hard rocks.

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Direct observation and experience of past earthquakes together with modeling carried out by researchers, has shown that ground motion acceleration and frequency is affected by the nonlinear behavior of site soil. In the process of assessing the seismic response of structures and lifelines, it is essential to understand the nonlinear behavior of the soil and how it can affect the results. In this paper, the nonlinear behavior of Urmia's subsurface soil is studied by performing one dimensional nonlinear site response analysis in time domain. Artificial acceleration time histories that were synthesized based on the result of seismic hazard analysis, conducted over three return periods, are used as input motion. Spectral acceleration at the ground surface is compared with those calculated for seismic bedrock, and spectral acceleration amplification curves are obtained. These curves show that, the amplification is greater in the central and eastern regions of the city than those for other regions of the city because of a deeper soil profile. The results show that the maximum amplification for higher return period is smaller because of greater soil nonlinear behavior

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For prediction of exact effect of soil temperature, soil water retention, unsaturated hydraulic conductivity and water flow of soils on seep development, information about soil hydraulic, physical properties soil temperature is necessary. In this study, using geophysical and thermal methods the hydraulic properties and thermal conductivity of unsaturated porous media was estimated. Infiltrated water temperature was 50° C and the temperature data used in inverse solution technique was recorded by 2 thermal sensors during 3255 sec. One of thermal sensor was installed at a depth of 50 cm and the soil hydraulic and thermal parameters were estimated using 48 collected data of the injection water temperature variations. In this research 121 geoelectrical sounding with the Wener, Schlumberger and polar-polar arrays configuration were used. Evaluation and interpretation of the sounding curves show that the water table is located at depth of 75 meters. Top alluvium layer (unsaturated zone) is composed of three layers. In this study, to investigate the distribution and diffusion of pollutants in the unsaturated zone, the brine concentration of 20 g/L was used. Wener and polar-polar arrays were used to detect and image the contaminants plume. The polar-polar configuration shows less spreading of contaminated plume in both vertically and horizontally direction than the Wener array.  Particularly by the Wener configuration the plume depth is more underestimated than the real value. Based on water injection visibility in the vicinity of the trenches and observing the water seepage at the trench face, the real velocity of the water at direction of 35 degrees relative to the horizon was measured equal to 0.159 m/h. Horizontal and vertical contaminant plume expansion coefficient was determined equal to 1.4. Evaluation of thermal and hydraulic properties of unsaturated porous media was done by HYDRUS-2D software. In this study five hydraulic parameters &thetar, &thetas, &alpha, n and Ks and five soil heat transfer parameters including the &lambdaL, &lambdaT, Cn, Co and Cw were included in the parameter estimation process. After implementation of the parameter estimation (adjusted for ​​observed and predicted temperature values) Coefficient of Determination  R² was equal to 0.97 and the objective function value was equal to 11.5. Computational error in the mass balance was about 67 percent. 

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This paper presents a case study of the instability mechanism, to verify and reinforcement method adopted construct collapsed zone of Sabzkuh water conveyance tunnel in southwest Iran. The instability problems were encountered during tunnel excavation due to the failure, changes in stress field lead to deformation causing dilation and increasing the permeability of sand and gravel layers, local fault gouge zones, landslide and in turn significant reduction in shear strength and collapse in tunnel. IPE Arch Support Technique (IAST) was, used for T1 part of Sabzkuh tunnel zone in order to reinforce the ground around tunnel and to cross the zone falling. In this study, Finite Element Method was employed for the quantitative reinforcement effect with deformation modulus of ground, IPE length and size. As a result, the settlement increases as length increases and decreases with the increase of the deformation modulus of ground and IPE size.  

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The Dynamic Probing is an important test in site investigation and geotechnical studies. It is used for determination of situation and specification of soil layers when the depth of exploration is moderate. In our country, in the last few years test has been widely used to replace the standard penetration. In this paper, the experiences to use different various types of dynamic probing rigs and the errors that can occur in these experiments are discussed. Then the accuracy of this test is studied to evaluate the specification of fine-grained soils. The most important innovation of this research is the proposition of the new correlations between cone dynamic resistance and undrained shear strength and so compaction percentage in fine-grained soils. The paper encourages the wider application and further development of this test for site investigation in fine-grained soils.

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The studied region in this research (Alborz province) is structurally located in Alborz poly_orogenic system of northern Iran. The purpose of this research is combining the remote sensing and geology sciences to show fault lineaments by analyzing satellite data in a vast region and also comparison between lineaments layer and recognized faults in geology maps. Firstly, two scenes of Landsat ETM+ satellite images with 164-35 and 165-35 numbers were mosaicked and also according to coordinates of research area (46^◦ 30´ to 48^◦ east longitude and 34^◦ to 35^◦ north latitude degree) have been crop. Then with remote sensing methods such as combination of bands, filtering, NDVI index to reconstruction the vegetation, principal components analysis (PCA) and band relativity in gray scale and color images  have been analyzed the satellite images. Finally, by using the above mentioned methods, the map of fault lineaments and map of lineaments density for Alborz province have been prepared and compared with recognized faults.

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In this research attempts were made to estimate the in-situ stresses acting on a hydrocarbon reservoir based on routine activities of acid injection in oil reservoir. It was found that the relation between the re-opening pressure of fracture and principal in-situ stresses can be estimated using rock mechanics equations for the circular underground cavities. An appropriate relation between the maximum and minimum horizontal principal in-situ stresses and reservoir parameters such as permeability, reservoir pressure, Young’s modulus, acid viscosity, injection flow rate and etc., was developed by using the well-known Darcy equations for fluid flow in porous media. Accordingly, knowing the flow rate of acid injection during well operations and some other reservoir parameters, in-situ stresses may be estimated. The method was then successfully applied to a large carbonate reservoir as a case study in south-west of Iran. Maximum and minimum effective horizontal stresses were calculated by employing the presented method. 

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One of the best approaches to reduce transportation problem is to use the underground tunnels. Therefore, Niayesh highway tunnel was performed by the New Austrian Tunnelling Method (NATM) in the northern part of Tehran and it includes north and south tunnels. The excavation of tunnels and other underground structures cause considerable changes in local stress conditions around structures that lead to surface settlement. In this research, surface settlement has been studied for five sections (CS-1 to CS-5) by empirical methods, numerical analysis and actual settlements. For the empirical and numerical methods, O’Reilly and New (1982) method and also finite element method (PLAXIS_2D software) have been used, respectively. On the basis of the obtained results, the numerical method in all sections (except section 3) is in agreement with the actual settlements. While, empirical methods have estimated the settlements more than actual values in those sections.  Also, the achieved results from the aforementioned methods show that the maximum settlement due to tunnel excavation is more than allowable settlement and it is in risk condition

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Several studies show that during and before the earthquake, ground water existing in layers of the earth crust undergoes physical and chemical changes. These changes are recorded by measurement devices and known as "Geohydrological Precursors". Based on the studies conducted in this field, earth electromagnetic field waves experience fluctuations during and even before happening of the earthquake, which are called "magnetic anomalies". This type of anomaly is known as "geomagnetic precursor" within the scope of earthquake knowledge. S, the aim of this study is to assess the feasibility of making a connection between two groups of earthquake precursors (hydrological and geomagnetic precursors). In the present research, a series of tests has been done in order to investigate the effect of magnetic fields on physical and chemical properties of water, including Electrical Conductivity (EC), Total dissolved solids (TDS), Height of Water (HW). The tests were designed and conducted to be used in short-term and middle-term earthquake prediction. Analysis of the experimental results using statistical tests indicates that there is a partial meaningful relationship between magnetic fields (geomagnetic precursor) and physical and chemical properties of water (hydrological precursors), with the confidence coefficient equal to 95 percent

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Mountains are usually formation origin of their neighbor land surface features such as hillsides and plains. some problems and errors may occur in application of RS technique for generation of geology maps and in separation of these units from other similar units. The main objective of this study is to integrate RS and geomorphology approaches for identification of different geomorphology units and finally separation of debris lime stones from massive lime stones in Bahadoran region, Yazd province. For this purpose, a Landsat ETM⁺ image was acquired together with band ratios, principal component analysis and factor analysis approaches to generate lime stone distribution map. Results of this study show that (integration of RS and geomorphology sciences) can better generate the lime stone distribution map compared with the first one