Geological Environment and Engineering
Shirin Samani; Ali Uromeihy; Amirhossein Enayati; Imandokht Mostafavi; Misha Pezeshki
Abstract
Diagenetic processes in carbonate rocks can be considered as one of the most important factors influencing the inherent characteristics of this type of reservoir on a small as well as large scale. Considering the importance of knowing the mechanical characteristics of reservoir rocks in geomechanical ...
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Diagenetic processes in carbonate rocks can be considered as one of the most important factors influencing the inherent characteristics of this type of reservoir on a small as well as large scale. Considering the importance of knowing the mechanical characteristics of reservoir rocks in geomechanical modeling and its application in the exploitation and development of hydrocarbon fields, it is necessary to find out how lithological characteristics affect its rock mechanical behavior. In this study, the impact of two diagenetic processes (Dolomitization and Anhydrite cement) on the physical and mechanical characteristics (such as Uniaxial Compressive Strength, Young’s modulus, Cohesion, and Internal friction angle) of carbonate reservoirs of the Kangan Formation, are addressed. The evaluations have been done in two phases: i.e., lithological studies and rock mechanical tests. The results show that changes in mechanical properties are strongly influenced by diagenetic processes. The two main influential features on mechanical characteristics are dolomitization and anhydrite cementation, which strongly affect porosity, dominant pore type, and mineralogy. The results show that dolomitization in the studied samples has caused an increase in porosity and a decrease in strength and elasticity. While the presence of anhydrite has caused an improvement in the resistance characteristics with an opposite effect.
Exploration and Mining
Yaghoob Zarei; Ali Uromeihy; MohammadReza Nikoodel
Abstract
In this labratory study, the effect of joint density (number and spacing) on the pressure wave velocity was researched in pyroclastic rocks. After determining the physical properties, the P-wave velocities of intact rock samples were measrued. Then, an artificial joint perpendicular to the measuring ...
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In this labratory study, the effect of joint density (number and spacing) on the pressure wave velocity was researched in pyroclastic rocks. After determining the physical properties, the P-wave velocities of intact rock samples were measrued. Then, an artificial joint perpendicular to the measuring direction was created in each sample, and the wave velocity tests were repeated. These tests were continued up to 5 joints with two sets of 2 and 5 cm spacing. Consequently, the data were analyzed using the statistical methods. The results show that the P-wave velocity was decreased by increasing the number of joints in both spacing sets, and thus an inverse linear relationship was obtained. However, as the number of joints increases, the reduction rates of wave velocity were different at two spacing sets. More precisely, up to 3 joints, the reduction rate in the 5 cm spacing set was more than that in the other set. Nonetheles, after the third joint, the decreasing rate in the 2 cm spacing set became greater. Generally, the shorter spacing had a more reduction (attenuation) in the P-wave velocity. In this regard, at a total of 5 joints, the reduction rate of the P-wave velocity in 2 cm spacing set was more than that in the other set.
Exploration and Mining
Mohammad Hassan Nazari; A. Uromeihy
Abstract
There are several outstanding factors engaged in the cement grouts filtration. These factors can be evaluated from some aspects including the characteristics of the grout, cement and grouting materials, grouting environment, interaction between the grout and environment and grouting pressure among which ...
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There are several outstanding factors engaged in the cement grouts filtration. These factors can be evaluated from some aspects including the characteristics of the grout, cement and grouting materials, grouting environment, interaction between the grout and environment and grouting pressure among which fewer studies have been performed on the role of the grouting pressure in the grout filtration. In this research practical results of cement grouting have been reviewed in two dam projects as examples. The results depict that the increase in the grouting pressure considerably affects the rate of cement take and penetration. In practice, the cement penetration into the rock is higher when the grouting pressure is variable. This is vice versa under constant grouting pressure. In other words, the increasing steps of grouting pressure may erode the grout cake at each stage. This leads to optimal penetration of the grout and decreases the watertightening costs of the dam foundation, tunnels and structures requiring cement grouting.
Exploration and Mining
A. Uromeihy; E. Sadat Razavi; V. Baghri
Abstract
Rasht City is capital of Gilan Provence and is considered as one of the metropolitans along the south coast of the Caspian Sea. In terms of geological setting, the city is situated to the north of the Alborz Mountains and in the Gorgan-Rasht sedimentary zone. The area is characterized by many active ...
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Rasht City is capital of Gilan Provence and is considered as one of the metropolitans along the south coast of the Caspian Sea. In terms of geological setting, the city is situated to the north of the Alborz Mountains and in the Gorgan-Rasht sedimentary zone. The area is characterized by many active faults, with the Khazar fault being regarded as the most effect one, which can produce a gravity acceleration of 0.3g for a major earthquake. According to geotechnical data from exploration boreholes, the ground surface along Line 2 of Metro in the city comprises mainly a sequence of silts and clays with interlayers of gravel and sand. Due to high level of groundwater table, abundance of fine-grained soils, high seismicity potential, and production of ground vibration during movement of the train, liquefaction can be expected to occur along the Metro line. The aim of this paper is therefore to evaluate the liquefaction hazard potential along the Line 2 of Metro of the Rasht City by preparing a hazard zonation map. Liquefaction hazard zonation mapping was carried out using data gathered from 14 exploration boreholes drilled to a depth down to 40 meters integrated into Analytical Hierarchy Process (AHP) in the GIS modelling system. In this regards, five layers of information including soil type, SPT number, overburden pressure, plastic index and maximum gravity acceleration were considered. The results indicate that the range of liquefaction hazard varies between low to very high, and the maximum rate of liquefaction is expected in BC2 and I2 stations (Sazeman-e-Ab and Husain Abad areas, respectively). Soil type and groundwater table are recognized to be the most effecttive agents in inducing potential liquefaction.
A. Uromeihy; A. Karim-khani
Abstract
Erosion and sedimentation are among the natural processes continuously changing the land surface. This deformation may affect the development activities of the coastal areas such as Bandar Anzali region. In order to evaluate the potential of erosion in the region, various methods ...
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Erosion and sedimentation are among the natural processes continuously changing the land surface. This deformation may affect the development activities of the coastal areas such as Bandar Anzali region. In order to evaluate the potential of erosion in the region, various methods of zonation mapping were reviewed. The region was divided into a number of grid lines and the weight of each grid was measured. The computer program Arc-GIS was used to calculate the weighing factors of each cell and finally to draw the zonation map. In this regard, five factors including lithology, slope angle, fault types, drainage pattern, and land-use (vegetation) were considered as major affecting factors on the erosion phenomena. The results showed that the effect of lithology and land-use are higher as accompanied by the effect of fault type and slope angle, and the effect of drainage pattern is most noticeable in mountainous areas. The geochemical characteristics of the sediments in Anzali wetland indicate that the percentage of SiO2, Al2O3, and CaO2 is higher than that of other elements such as FeO, MgO and MnO. These sediments represent the lithological setting of the provenance region of the originated sediments.
G. Barzegari; A. Uromeihy
Abstract
Development of liquefaction in saturated cohesionless deposits is one of the most dramatic causes of damage in civil structures during earthquakes. The potential damage caused by liquefaction includes: 1) loss of bearing capacity, 2) excessive settlement, 3) lateral spreading, 4) flow failure, and 5) ...
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Development of liquefaction in saturated cohesionless deposits is one of the most dramatic causes of damage in civil structures during earthquakes. The potential damage caused by liquefaction includes: 1) loss of bearing capacity, 2) excessive settlement, 3) lateral spreading, 4) flow failure, and 5) ground oscillation.
The liquefaction susceptibility of a specific deposit is affected by many factors for example, wave-induced liquefaction characteristics, soil type, geological history, confining pressure, permeability, relative density, water content, and properties of the soil grain size.
Chapar-Abad Dam is an inhomogeneous earth-fill dam with height and crest length of 44.5 and 427 meters, respectively. The reservoir capacity is 127 million cubic meters. The dam which is under construction is located about 75 km southeast of UromiehCity, in West-Azerbaijan province. The foundation materials include 60 meters of alluvium deposits overlying the bedrock layers of carbonate units. The abutments consist of carbonate and schistose layers of Precambrian age. In this paper the potential of liquefaction of the site is evaluated according to the SPT results form in-situ tests performed in boreholes driven into the depth of alluvial deposits. Furthermore, recently modified relations of correction factors such as stress reduction factor (rd), earthquake magnitude scaling factor for cyclic stress ratios (MSF), overburden correction factor for cyclic stress ratios (Ks), and the overburden normalization factor for penetration resistances (CN) are presented and used in liquefaction assessment of alluvial foundation at Chapar-Abad Dam. The results indicate the possibility of liquefaction and instability of granular soils during earthquake and any types of strong motions.
M. Talkhablou; N. Hafezimoghaddas; M. Nikodel; A. Uromeihy; M. shafiefar
Abstract
Rocks are natural materials used in a variety of coastal protection structures, especially in rubble mound breakwaters. Engineering properties of rocks, such as durability and resistance to degradation factors of the marine environments are important properties which ...
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Rocks are natural materials used in a variety of coastal protection structures, especially in rubble mound breakwaters. Engineering properties of rocks, such as durability and resistance to degradation factors of the marine environments are important properties which construction material of marine structures should behave. Rock durability is a function of rock properties and condition of environment in which the rock will be used. Regarding the economical importance of constructed coastal ports and facilities in coast lines of south Iran, it is necessary to evaluate the engineering properties of rocky construction materials in such structures from durability and degradation point of view. In this study, by investigating and sampling the used rock material in 27 constructed rubble mound breakwaters along the 1000 km south Iran's coastlines, from Amery Port in western part to Pasabandar Port in 85 km east Chabahar, and regarding the observations that collected in field visual investigations and engineering tests of durability examination, the experimental relationship between physical, mechanical and durability parameter of studied rocks have been concluded and consequently criterion to select the suitable rock of three groups of rocks limestone, igneous rock and bioclastic sedimentary rock (lomashell) have been presented individually.
N. Ghazipour; A. Uromeihy; I. Entezam; F. Ansari; M. Pirouz
Abstract
Karaj-Chaloos Road is always considered as the most hazardous road due to rockfalls and landslide events. The road, located in the CentralAlborzMountains, is a vital route connecting Tehran and the southern part of Alborz to the northern part and the resort areas ...
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Karaj-Chaloos Road is always considered as the most hazardous road due to rockfalls and landslide events. The road, located in the CentralAlborzMountains, is a vital route connecting Tehran and the southern part of Alborz to the northern part and the resort areas along the Caspian Sea. The aim of this paper is to study and evaluate the potential of rockfalls and landslides along the middle part of the route. The study area has a very complicated geological and geomorphological condition and many deep cuts were made along the road to provide a safe passage through the mountains. Since most of the slope instabilities along the road are of rockfall type, cone-fall theory proposed by Evans and Hungr (1993) was used to analyze and predict the rockfalls along the route. The results show that the potential of rockfall is directly related to morphology and higher for steeper slopes. Rock type and the geological structures of the slopes also influence the rockfall potential in the study area.