Journal of Engineering Geology

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Abstract
(Paper pages 1159-1178)
Young’s modulus measured as the slope of the stress-strain curve under static loading conditions (Es) in the lab is one of the most essential parameters for reservoir geomechanical modeling. However, information on the value of Es along the well length is often discontinuous and limited to cross well with the core. On the other hand, well log data for wave velocities Vp and Vs are often available for most hydrocarbon reservoirs. Hence, well-known equations are needed to calculate static Young’s modulus based on the compressional and shear wave velocities (Vp and Vs) that is dynamic Young’s modulus (Ed). Unfortunately, because of porosity and micro cracks in rock texture, Es and Ed are not equal. Therefore, correlation between static and dynamic parameters could result in a continuous and more reliable knowledge on the elastic parameters along the well length. In this research, laboratory experiments were carried out on limestone rock core specimens of Sarvak formation obtained from an oil well in the South West of Iran. Empirical relations were suggested to estimate UCS and static Young’s modulus from compressional wave velocity (Vp) and dynamic Young’s modulus. These empirical relations are prerequisite for continuous wellbore stability analysis in oil and gas well drilling

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The pseudo-static analysis is one of the conventional methods in embankment dams design and International Commission on Large Dams (ICOLD) suggests using this method before ultimate dynamic analyses. In this research, the static, pseudo-static and dynamic analysis of Masjed Soleyman embankment dam was performed. Using dynamic and pseudo-static analyses results, the safety factor of critical sliding surface was calculated. Permanent displacements of critical sliding surface were evaluated by New mark method and the calculated safety factor was compared. Based on the comparison results in different water levels of the reservoir and by introducing a new equation, the variable horizontal acceleration coefficients in height of the dam body were calculated. Finally, the obtained horizontal acceleration coefficients were compared with the other criteria introduced in different embankment dam's design codes. Totally, the results indicate that the proposed method leads to a larger horizontal acceleration coefficient in higher parts of the dam body.

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Earth-fill dams stability in steady state seepage condition is very important, especially during earthquakes. Numerical software analyses require accurate and realistic modeling of construction stages. Since earth-fill dams are constructed in different layers, so these conditions should be considered in software modeling to achieve a reasonable design. In this study, an earth-fill dam is modeled in PLAXIS software and the effects of the number and shape of layers are studied in dry and steady-state conditions. Obtained results in static and pseudo-static analyses show that modeling of earth-fill dams with different layers has significant effects on shear stresses and horizontal displacements. For example, horizontal displacements and shear stresses, increase at least 50% and 17% respectively, in comparison with single layer models. According to the obtained results, it can be mentioned that modeling of an earth-fill dam in the layered model and rather in inclined layers are more reasonable

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Introduction
It is very important to have knowledge on the rock deformation modulus when designing geotechnical ‎structures and modeling oil reservoirs. In general, there are two destructive or static and non-‎destructive or dynamic methods for determining the rock deformation modulus, but considering the ‎time and cost of destructive methods proportionate to the depth, it is more common to make use of ‎non-destructive approaches. The outcrops of Asmari Formation are widely spread in the west and ‎southwest of Iran, and many engineering projects have been constructed or are being studied ‎on this formation. Therefore, it is of great importance to study on the geomechanical characteristics of this ‎formation. Presentation of empirical relations regarding the relationship between static and dynamic ‎moduli, with respect to the studies carried out in other parts of the world and the dispersion and ‎independence of studies done on Asmari Formation due to its large extent on one hand and the ‎importance of this formation in terms of oil and development civil projects on the other hand, necessitate ‎presenting a comprehensive criterion resulted from all studies carried out on Asmari Formation which ‎can express the relationship between the static and dynamic moduli. This paper represents the ‎relationship between the dynamic and static moduli of the site using the moduli obtained by the ‎down-hole geophysical method and the static moduli obtained by the intact rock test results of ‎Ghalajeh tunnel located in Asmari Formation in Ilam province. Then, a comprehensive relation is ‎presented to express the relationship between static and dynamic modulus by studying the previous ‎researches and criteria on this formation.
Material and methods
Two sets of tests were conducted to determine the relationship between static and dynamic moduli in the Ghalajeh tunnel. First, a uniaxial compression strength test was performed on 13 cores taken from three boreholes to compute the elasticity modulus in accordance with ISRM standard. Then, down-hole test was conducted on two boreholes such that to determine the dynamic modulus using compressive and shear wave velocities. Seismographic apparatus of ABEM RAS 24 as well as three-component down-hole geophones were utilized in order to plot the seismic profile. After the performing the tests, the dynamic modulus of deformation was calculated using the velocity of P-waves and the density of the host rock.
Discussion and Conclusions
By conducting in-situ static and dynamic laboratory tests on Ghalajeh Tunnel project and determining the values ​​of the static and dynamic deformation moduli, a relation was presented between them. Then, taking into consideration the previous models studied in Asmari Formation, a comprehensive criterion was presented for wider use in the mentioned formation. Given the root mean square error (RMSE) and variance account for (VAF), the values predicted using the proposed comprehensive model have acceptable accuracy. In the interim, the correction factor between dynamic and static moduli in Asmari Formation was between 0.8 and 2.4. The results show that, in general, the relationship between static and dynamic moduli is linear up to a certain range (static modulus of 100 MPa) and then it has a power trend./files/site1/files/124/4darai%DA%86%DA%A9%DB%8C%D8%AF%D9%87.pdf

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Introduction
"Sulfide-carbonate" deposit is a term, which comprises a series of sulfide minerals such as Zn-Pb ore minerals, mainly considered as related to weathering of Zn-Pb sulfide concentrations and influence in sedimentary hosts (carbonate). There are more than 350 Zn-Pb deposits located in Iran, including world-class deposits such as Angouran, Mehdiabad and Irankouh. Due to the mining activity of these deposits, it creates a significant amount of mine waste that releases of these wastes in the environment causing severe problems. One of the main problems is the formation of Acid Mine Drainage (AMD). AMD is produced by oxidation of sulphide minerals, particularly pyrite (FeS2) in waste dump. Due to low pH and the ability to dissolve metals and other compounds, it can host a number of environmental problems. A phenomenon known as natural or alkaline mine drainage (NAMD) occurs at high pH values ​​when the neutralizing minerals are significantly present in the mine waste or when the oxidation of the sulfide minerals is poor. However, the metals and cationic species, such as Cu, Pb and Cd, are more soluble at low pH. In contrast, elements that form anionic species, such as Se, Cr, V, and Mo, tend to be more soluble at high pH and Ni, Zn, Co, As, and Sb, are soluble at near-neutral pH, and can potentially contaminate mine effluents, even without acidic conditions. Therefore Acid or Neutralization potential (AP&NP) of waste dump is significantly affects on the composition, transfers and fates of contaminations transmitted from waste dump. The aim of this study was to monitoring heavy metals concentrations and assessments of pollution potential of waste dumps in Anguran mine by static method and has been compared by mineralogical approach.
Material and methods
The Angouran Zn-Pb deposit is located in the 135 kilometers southwest part of Zanjan Province, NW Iran. This area belongs to the northwestern part of the Sanandaj-Sirjan Zone, a metamorphic belt related to the Zagros orogeny. Angouran mine is one of the most important carbonate hosted Zn-Pb deposits in Iran that mining activity has been created a significant amount of waste dump in around pit. To achieve the goals, the 47 samples taken from different surficial parts of the waste dump were analyzed by using the ICP-MS method to determine the concentration of elements and heavy metals. These elements and metals includes: Ca, Mg, S and As, Cd, Cr, Cu, Ni, Pb, Zn. The pollution index (PI) were modeled for heavy metal contamination risk zoning then modified Acid Base Accounting (ABA) static method was used to evaluate of acid and neutralization potential (AP&NP) of the waste dump samples and the results were modeled by Kriging method. At the end, mineralogical approach (Mg + Ca concentration) was used to determine the source of neutralization and to better interpret the static results.
Results and discussion
The results of contamination index showed that zinc, arsenic and cadmium had the highest average contamination index (18.89, 12.13 and 5.8, respectively) and the trend of total metal changes in the region as Zn> As> Cd> Pb > Ni> Cr> Cu was rated.
Datas measured in modified ABA method were modeled in 2D maps using the Kiriging method. Due to the low total sulfur content (less than 1%), all of the samples were Net Neutralization Potential (NNP) with a range of 49- 990 kg calcium carbonate per ton, and the study area was classified into three neutralization potential (NP), High (NP) and Very High (NP) levels. The mineralogical approach (Mg + Ca concentration) was used as a useful tool for better interpretation of modified ABA results and determines the neutralizing source. Mineralogical approach results indicate that calcite species are the main source of neutralization and have high correlation coefficient (R = 0.99) with the modified ABA method. In order to validate the results, the presence of mineral calcite was confirmed by XRD analysis on 4 samples.
Assessment of AP and NP of sulfide – carbonate waste dump in this research can be used as a basis model for other similar mines to control environmental problems and to identify the behavior and to transfer heavy metals in mine drainage in the future. Mineralogical approach results show that neutralizing potential and neutralizing source can be obtained without using expensive mineralogy analyses in this type of carbonate-sulfide deposit



 

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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 E_s. In addition, comparing the results of the principal components regression and the support vector regression indicated that the latter outperformed the former.

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