مجله یافته های نوین زمین شناسی کاربردی
پیاپی 25 (بهار و تابستان 1398)

Determination of geotechnical parameters required for design of rock mass structures are one of the major issues in the engineering geology, civil and mining. Uniaxial compressive strength and tensile strength are among of these parameters which are widely used in the design of structures in rock mass. Among them, the point load index test not only has less cost and difficulty than uniaxial compressive strength and tensile strength tests; but also can be carried out at the site of the project and on samples with irregular geometry; therefore, it can be used as a criterion for the initial engineering judgment regarding tensile and compressive strength of rocks. In the research, the relationship between these parameters is analyzed with statistical analysis and the best experimental relations are presented. Moreover, due to the vast spatial occurrences of carbonate rocks in the country and their application in various development projects, the relationship between uniaxial compressive strengths, tensile strength and point load strength with aggregate impact value is also studied, which is one of the indicators for assessing the quality of materials stone. In the bivariate equations, the highest coefficient of determination is 0.897, that related to the relationship between the uniaxial compressive strength and the point load index in dry condition and the lowest coefficient of determination is 0.653, that relates to the relationship between the Brazilian tensile strength and the aggregate impact value in dry condition, also the use of multivariate regression leads to a much better estimate of uniaxial compressive strength.

In Robat-Arregijeh Pb-Zn deposit, various exploration activities have been carried out through two methods, indirect and direct in two stages. In current research, at first, depending on the exploration data in first stage including geophysical data surveyed by gradient configuration, surface explorations and geology information, promising areas were detected using knowledge driven fuzzy logic method. To achieve this goal, various layers of evidence including geophysical, faults, geochemical and geological layers were prepared in ArcGIS environment. Afterward for weighting and prioritization of exploration layers, among the variety of multi-criteria analysis and decision making (MADM) methods, fuzzy TOPSIS method was selected due to high sensitivity and accuracy in decision making. In order to perform hierarchical chart, Delphi method was also employed. In this regard, four criteria comprising accuracy and reliability of the results, time and cost of operation, number of data and interpretation of the results were considered. After ranking the informational layers and according to them prioritize, final mineral potentials map was produced using weighted sum method. Then, deep geophysical exploration in the region was validated through determination of linear correlation between geophysical data after smooth inverse modeling with lead-zinc assay of deep exploratory boreholes (related to the second stage of exploration operation) located on the geophysical profiles. Finally after ranking the informational layers, the mineral potential map was validated with accuracy percentage of about 56% through the existent borehole assay data.

Uniaxial compressive strength (UCS), modulus of elasticity (E) and Brazilian tensile strength (BTS) are important properties of intact rock which are used widely in rock engineering. The determination of these parameters in laboratory is difficult, expensive and time consuming. Thus, it has been attempted that the empirical equations to estimate the mechanical properties of sandstones using P-wave velocity and Schmidt hardness as two non-destructive and easy tests were developed. For this purpose, 30 rock blocks of sandstone have been collected from several parts of Upper red formation in southwestern Qom and they were tested in the laboratory. The laboratory tests include the determination of P-wave velocity and Schmidt hardness, and mechanical properties include the uniaxial compressive strength, modulus of elasticity and Brazilian tensile strength. Empirical equations have been developed for estimating the mechanical properties from P-wave velocity and Schmidt hardness using regression analysis. To check the validity of the empirical equations, t and F test were performed, which confirmed the validity of the proposed empirical equations. Moreover, the results show that P-wave velocity appears to be more reliable than the Schmidt hardness for estimating the mechanical properties.

Shrinkage and swelling has been opposed and any soils that drying shows mark of shrinkage and cracking; is ability of swell when absorbs water. Soil swelling is reversible phenomenon. That’s mean shrinks the soil after decreasing moisture; so it is natural checked the phenomenon shrinkage, also.
Tabriz Northern Highway route is located on fine-grain soils that have been creation of clay and marl soils. This highway has a very young age but effect of geological phenomena on the various pieces of this route has caused creation longitudinal and transverse fractures and cracks, that one of the destructive phenomena is swell and shrinkage of the fine-grain soils. In this research, after local investigation, sampling has been done and by determining the shrinkage limit with using indirect and direct methods, the swelling potential of fine-grained soils of this highway has been investigated. On the samples has conducted tests of particle-size analysis, determination of limits Atterberg, and free swell. All specimens were classified as CL according to the USCS classification. Activity of samples is less than 1 and clay content is between 24 and 34 percent. Shrinkage limit between 12 to 18 percent, plasticity index between 10 to 23 percent, and free swell with use consolidation device (Oedometer) between 3 to 10 percent has been determined. Also, shrinkage limit of samples has been determined by drawing Casagrande curve based on plasticity index and liquid limit and this result was obtained that is a good accordance between free swell and tests. At last swelling potential of samples has been determined based on empirical relationships and swelling potential of soils is between low to medium.

Thermal property means the material's response to heat application. When energy (in the form of heat) is absorbed by a solid material, its temperature, and subsequently its dimensions, increase. The energy may be transferred to the cooler regions of the sample and may even melt the sample. The mechanism of heat transfer in rocks is very complicated. Rocks are composed of mineral particles with various chemical compositions and various degrees of crystallization. Therefore, the thermal properties of rocks depend not only on the pressure and temperature, but also on the mineralogical composition, the structure and geometry of pores, the size of the particles and the shapes of cracks. The main thermal properties of rocks include heat capacity, thermal conductivity, thermal diffusivity and thermal expansion, which they are needed for numerical modeling, considering the effects of temperature, including the modeling of oil wells, gas storage caverns, nuclear waste disposal site, and deep mines. In the present study a device for determining one of these properties, the coefficient of thermal expansion, is developed. To evaluate the efficiency of the device, the values of this coefficient in the sandstone, andesite, the green tuffs of the Karaj formation and limestone are determined. The results are consistent with the results of the experimental studies on rocks found in the literature.

determining the potential of karst is necessary to study the resources of karst water. This is paper the potential of karstification with use of lithology, precipitation, slop, vegetable, stream, density and frequency of fractures has been carried out with Analysis hierarchy method in ARC GIS Version 10.2 environment. In this method, the layers are compared and weighed in a pair manner. In order to the examination of layers have been considered two groups. The first group: Average rainfall annual, lithology of formations and fracture density. The second group is slope, vegetation and density stream. The first group is more important in development of karst. The two groups were separately weighed and then the two groups were compared and weighed. Translation error The highest weight in the first group was related to the average precipitation annual, and in the second group, the density of the stream had the highest weight. the first layer is attributed the weight of About 70%. The narrow strip from eastern to northeastern parts of Khozestan province has karstic potential of water sources. The validation model has been used the proposed large springs in the study area. The results show high adaptation the model with springs of basin in the area.

The Rashakan limestone mine as supplier of Urmia cement plant is producing about 3 million tons of limestone ore. The proximity of this mine to the Urmia railway and the main transit road of Urmia-Mahabad, as well as the destructive effects of vibration and noise caused by mine explosions on residential and environmental area, has caused the use of continuous surface miner machines as one of options for continuation of mining operations. Determining the ease of rock mass extraction, which is referred to as the excavatability index, has a vital role in the decision making stage for the selection of methods and extraction machines. This paper investigate the feasibility of mechanized extraction based on the geomechanical characteristics of Rashtkan limestone mine rock mass. In 18 different sections of the of 8 geomechanical zones of the mine, geomechanical parameters including weathering, uniaxial compressive strength (UCS), joint spacing and layers thickness were measured by field and laboratory surveys. Based on the diggability index rating method, the excavatability of the zone (7), (1, 6), (8), (3 and 5) is classified in the hard, relatively hard, easy and very easy excavation classes. In the following, considering the uncertainties in the results of the classification systems, one of the most recent applied classification methods based on continuous rating is used. The results show that the estimation of both continuous and conventional rating methods for the three zones of 1, 6 and 8 is the same and for the zones of 3, 5 and 7, the continuous rating method suggests easier excavation condition. According to the results of this research, the geomechanical conditions of Rashakan limestone rock mass are appropriate for mechanized extraction and the use of continuous surface miner machines. It is recommended that in order to correct selection of the type and capacity of extractive machinery a technical and economic analysis be conducted based on the investment and the operational costs of each of the different options for different types of machines.

The Skavagh study area is located in the western of the Alborz-Azarbaijan folded belt. The dominant rocks in this area are volcanic and volcanic-sedimentary rocks with the Eocene-Oligocene age which have covered most of the area. As well, the late Oligocene intrusive bodies with intermediate composition have cut the rocky units of the area. Generally, metal mineralization in the Skavagh area is copper and manganese which has occurred in the Eocene volcanic and volcanic-sediments rocks. In this research, satellite images of Sentinel 2 and Landsat 8 have been used to perform different methods of supervised classification and prepare a geological map. In this study, after performing the necessary pre-processing, the supervised classification of the images was carried out in different ways, and finally, by conducting field studies, the best method was selected based on the geological evidence. Finally, after calculating the error matrix, the accuracy of the data, Kappa coefficient and by comparing with the index samples and sampling and the thin sections of the geology, the method was validated. After sampling and statistical analysis, it was determined that the spectral angle mapping method showed the best match with the geological units of the region.

Heavy metal concentration and speciation in soils and native plants around the Ijo copper mine (Kerman province) are investigated in the present study. For this purpose, 34 soil samples (0-40 cm in depth) and 8 native plants (Artemisia sp.) are collected and analyzed by means of standard methods. In addition, chemical forms of heavy metals are determined by Tessier five-stage extraction procedure. The results obtained indicated that Cu (457.25 mg/kg on average) in potassic alteration zone and As, Pb and Zn in argillic (47.06, 137 and 580 mg/kg on average, respectively) have the highest concentrations. The calculated enrichment factor (EF) and geo accumulation indices (Igeo) also confirmed this distribution pattern. The results of sequential extraction method indicated that all the metal studied have relatively low proportion in the exchangeable fraction (F1, 1/89 % of their total contents) and high contribution in the residual fraction (79/70 % of total contents) implicating their main geogenic sources in the soils. Levels of heavy metal in Artemisia and based upon the calculated biogeochemical indices (Transfer factor-TF and Bioconcentration factor-BCF), it was revealed that Zn and Cr (Mn as well) have the highest and lowest transfer factors, respectively. Also, the highest BCF are calculated for Mo, Cd and Cu. This study generally concludes that although the metals in soils are inherited mainly from the natural or lithogenic source in the study area, intensive exploitation and mining activities might enhance the soil metal contamination rate and make metals more available that it should be considered in future assessments.

This study deal with the effect of anisotropy on strength behavior and failure patterns of Borujerd area slates under Brazilian test conditions. For this purpose, 6 rock blocks were taken from different locations in north and east of Borujerd. After sample preparation and assessment of mineralogical and physical properties, the Brazilian tensile strength test was performed on the disc-shaped samples in 7 anisotropy angles (between the loading direction and anisotropy plane) including 0, 15, 30, 45, 60, 75 and 90°. The results indicate that the maximum BTS is observed at β = 90° for all samples. While, the lowest value of BTS corresponds to anisotropy angles (β) equal to 15° and 30°. The observation of failure patterns of samples after Brazilian test shows that there are three types of dominant failure patterns including parallel to the anisotropy (PA), across the anisotropy (AA) and curved fracture (CF). Transitional angle, which indicates the change in dominant failure pattern from parallel to the anisotropy to across the anisotropy, were also determined. Finally, the relationship between fractures length and Brazilian tensile strength was determined for selected slates.

Groundwater in some of the agricultural wells of Hamadan Province (including around the Hamehkasi village) has bubbles of gas and physically its taste is sour, bitter and burning. To postulate its origin and the trend of variation of the composition is important task for planing and continous using. Therefore, in this research, the origin of anomalies and the trending of its composition change was evaluated. For this purpose, six gaseous wells were identified and their electrical conductivity was monitored15 times over three years (five times each year). The trending of their electrical conductivity changes were evaluated by SPSS software. Additionally, from each well, one sample was collected and for determination of the total alkalinity, Electrical Conductivity, Cations and Anions were analyzed. Thier chemical indices were calculated and evaluated by using different diagrams. The results showed that the water of all wells is fresh, show the Ca-Mg-HCO3 type. In these waters, the concentration of soluble carbon dioxide is more than 1000 mg/L. The abnormal composition of wells water due to from reaction between the water and the reservoir rock with involvement of hydrothermal fluids. Part of the reservoir rock consists of lime and the other part consists of marl and evaporite sediments. The statistical analysis of trending of water composition change indicates that the electrical conductivity decreases significantly over time, which firstly, confirms the involvement of hydrothermal fluids in rock-water reaction and secondly, it will be the hope of improving the water quality in future.

Ardakol fault with the length of 125 km and dextral strike-slip mechanism is located in the northern part of Sistan suture zone. This fault caused an earthquake with the magnitude of 7/3 Mw in the region on 10/05/1997 and caused the longest coseismic rupture associated with earthquakes in recent Iranian centuries. Comparison of seismic moment, geological and geodetic values shows that the changes in moment ratio are directly related to the length of the fault, as the length of the fault increases, the moment increases as well, and as a result it releases higher levels of energy. The study of the moment and fractional changes for the Ardakul fault shows that the energy released rate in the northern part is higher than that of the southern section, which means that in the northern parts, more earthquakes occur and therefore the number of active faults is larger. In general, the seismic moment of the Ardakol fault is decreasing from north to south and as a result, more energy is stored in the South or deformation in the southern part, so, southern parts are in danger of more earthquakes.