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Construction and Building Materials (09500618)452
Porosity is among the basic physical parameters widely used in evaluating the strength characteristics of building stones. Based on the geometric shape of the stone specimen, there are two procedures for determining the porosity: 1) measurements on specimens with regular shapes and 2) measurements on specimens with irregular shapes. The present study correlates the strength characteristics of stones and porosities measured from specimens with regular and irregular shapes. To this end, samples of carbonate stones were collected from different locations in Iran. The porosity of the samples was measured for specimens with regular (nr) and irregular (nir) shapes. Next, the strength characteristics of the samples, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and point load index (PLI), were determined. Results revealed that for all samples, nr has lower values than nir. Based on the scanning electron microscope (SEM) micrographs, this difference is due to the filling of some pore spaces of the specimens with regular shapes during their preparation by the coring machine. UCS, BTS, and PLI(50) were correlated with nr and nir using simple regression analyses. The accuracy of the correlation equations was compared based on their determination coefficient (R2) and diagonal line (1:1) measures. The findings indicated that nir provides higher accuracy than nr in evaluating the UCS, BTS, and PLI(50) of the samples. The effect of dry density (ρd) on the correlations between UCS, BTS, and PLI(50) with nir was investigated using multiple regression analyses. According to the results, ρd has a positive role in the prediction accuracy of the UCS, BTS, and PLI(50). The validity and accuracy of multiple regression equations were verified according to the statistics criteria and the published data by various researchers. Using these equations obviates the need to perform the UCS, BTS, and PLI(50) tests as time-consuming and laborious efforts. © 2024 Elsevier Ltd
Dadadszadeh n., ,
Hashemi, M.,
Gazifard a., ,
Asghari-kaljahi e., E. pp. 845-852
Tabriz is one of the largest cities in Iran, with a population of more than 2 million. Marlstone is the bedrock of most areas of the city. These marls, consisting of lime and clay, are found in different colors such as yellow, olive, and gray, which mostly belong to Baghmishe and Upper Red Formations. These marls have different amounts of organic materials and in high percentages cause the formation of lignite. The physical characteristics of the marl are different and the gray marl has a high density and strength. Another important characteristic of marls is the high rate of weathering which in excavations, changes over several months and turns into soil. Therefore, marl is considered both a weak rock and a hard soil. This study, by sampling and conducting experiments, presents the physical and mechanical characteristics of gray marls in different parts of Tabriz city. The carbonate content of the mentioned marls is between 30 and 60% and their dry unit weight is between 17.5 and 20.0 kN/m3. The clay minerals in these marls also include illite, montmorillonite, etc. © 2023 selection and editorial matter, Askar Zhussupbekov, Assel Sarsembayeva & Victor N. Kaliakin; individual chapters, the contributors.
Environmental Earth Sciences (18666299)81(2)
The Meymand world heritage site (Kerman Province, Iran) is a rock-hewn village carved within a pyroclastic rock mass, Meymand Tuff. This site, having an ancient local population with an age of 2000 years, is hosted by a weak rock exposed to deterioration and weathering processes. However, our understanding of the characteristics of the Meymand Tuff is limited to some previous general studies. Therefore, in the present study, the stratigraphy and intrinsic characteristics of the Meymand tuff are investigated to determine its weathering behavior and durability. For this purpose, comprehensive field and laboratory investigations were carried out. The stratigraphy of the valley and the pyroclastic flows that had deposited the Meymand tuff were identified and outlined based on field investigations and many surveyed sections along the Meymand valley. Next, the mineralogical composition, texture, structure, physical and mechanical properties, water absorption rate, slake durability, wetting–drying durability, shrinkage potential of the fine portion, and collapse potential of the Meymand tuff were assessed through laboratory investigations. The results revealed that two pyroclastic flows had deposited the host tuff rocks of the Meymand site. These rocks have a heterogeneous texture comprising very coarse-grained clasts to the fine-grained matrix. Rock characteristics including heterogeneous texture, high porous and open structure, clay-rich mineralogical composition, high water absorption capacity, and swelling and shrinkage potential of the fine portion of the matrix have resulted in adverse behaviors in Meymand tuff. These behaviors are pertained to the strength softening, weight loss, and deterioration at wetting drying cycles. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Bulletin of Engineering Geology and the Environment (14359537)79(7)pp. 3785-3796
Evaporite rocks of the Gachsaran Formation make the reservoirs and foundations of several important dam site in southwest Iran. The solubility of these rocks is the main cause of instability and leakage problems usually observed in these dam sites. Therefore, investigation and consideration of engineering geological characteristics of these rocks, including their solubility, is crucial. In the present study, 10 gypsum rocks of the Gachsaran Formation were selected from Masjed-Soleyman, Haftkel, and Ramhormoz areas in southwest Iran. The chemical and mineralogical compositions of the samples were determined through optical microscopy, XRD, and XRF analyses. Different characteristics of samples including physical and mechanical properties, solubility, and solution rate were determined. Then, the effects of the chemical composition of gypsum rocks on geomechanical characteristics, solubility, and solution rate were assessed. Results showed that the proportion of two main gypsum components of CaO and SO3 and the CaO/SO3 ratio has a significant effect on gypsum strength and solubility. Also, an increase in the abundance of minor oxides of Al2O3, Fe2O3, SiO2, and K2O leads to a decrease in the solution rate. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
Arabian Journal of Geosciences (discontinued) (18667538)13(4)
Rate of penetration of a tunnel boring machine (TBM) in a rock environment is generally a key parameter for the successful accomplishment of a tunneling project. Tunneling time is one of the factors that determine the tunneling method (blast or mechanical work). In traditional method, tunneling time depends on the progression function of blast cycle, while in mechanized tunneling method the required time for boring is determined by advance rate and consequently penetration rate. The advance rate is a function of penetration rate of TBM, which is the ratio of the length of boring part of the tunnel to the excavated time of the same part. Penetration rate, on the other hand, is a function of lithology and geomechanical properties of the rock and also the boring machine. So far, many efforts have been made to develop a method to predict the penetration rate (TBM) of the machine. Among these methods are empirical models, particularly NTH model, including models that can be used to predict the penetration rate. In this study, statistical analysis was used to obtain importance of parameters involved in penetration rate and compare the performance of neural networks with other mathematical models based on the principles of probability. In addition, the artificial neural network (ANN) was compared with models of Innaurato and NTH, which indicates high performance of neural networks in predicting penetration rate compared with the other two models. As a result, neural network was chosen and then proceeded to build the network optimized. © 2020, Saudi Society for Geosciences.
Environmental Earth Sciences (18666299)79(13)
In the present study, an experimental investigation was conducted to examine the effect of the size of additives on the improvement of collapsible soils. For this purpose, three collapsible soils with severe collapse potential were selected from Varamin Plain, Iran. The selected soils were then treated in the laboratory by the addition of alumina materials in two sizes of 70 nm (nano-alumina) and 685 nm (micro-alumina) and in different contents to improve their mechanical properties. Soil properties including collapse potential, uniaxial compressive strength, compressive modulus of elasticity, direct tensile strength, and tensile modulus of elasticity were selected as the target parameters for the improvement. These parameters were measured and determined before and after the treatment and the behaviors of treated soils were studied in both compression and tension states. The obtained results indicated that the nanometric and micrometric additives have diverse effects on the performance of the treated soil under compression and tension conditions. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
Geotechnical and Geological Engineering (09603182)36(4)pp. 2021-2035
This study discusses the engineering geological investigations for site selection of Abnahr Damsite, in order to select a suitable site from two alternatives. The alternatives are located on Mehrian River, relatively close to each other. Two alternative axes are located on an alternation of marlstone and limy marlstone. Although the rock types in both axes are the same, the engineering geological investigations revealed that their geomechanical characteristics are somewhat different. Based on these differences, one of the axes is more suitable. In this study, two alternative axes were investigated to determine their geomechanical characteristics including rock mass permeability, rock mass quality, RQD, Alluvium conditions, slope stability, and paleoslides. The suitability of the axes was finally judged based on all obtained characteristics of two alternatives. In order to make a rational decision, the analytical hierarchy process technique was used as a decision making support tool to quantify the subjective and descriptive judgments to subjective values. The results show that use of this type of systematic approach in decision making processes is very useful, especially for dam site selection. © 2018, Springer International Publishing AG, part of Springer Nature.
Environmental Earth Sciences (18666299)77(1)
Meymand, a historic 2000-year-old village, is an important heritage site in Iran that was included on the World Heritage List in 2015 by UNESCO. The village is located in a volcanic terrain, and its structures, such as houses, a mosque, a public bath, and a fire temple, have been carved in to the pyroclastic rocks of the Masahim volcano. In the present study, the engineering geological and geoenvironmental aspects of the Meymand village were investigated, including the geomorphology and landscape of the village, the technical classification of the pyroclastic rocks and their geomechanical properties, and the geoenvironmental characteristics and problems of the village. The engineering geological characteristics of the Meymand site were also compared with those of similar sites of the Cappadocia region in Turkey and the Kandovan village in Iran, which were widely studied by earlier researchers. The results of the present study indicated that the erosion of massive volcanic rocks free from systematic structural discontinuity has formed the unique landscape of the village, which is different from similar other sites. According to technical classification, the Meymand pyroclastic rock is a lithic tuff of a low degree of welding that has very weak strength and low durability. Accelerated weathering tests that artificially simulated the Meymand site conditions suggested that the Meymand tuff is prone to atmospheric conditions as its strength and deformability are drastically reduced when it becomes wet or saturated. Laboratory tests and field evidence show that the Meymand village is under threat of erosion due to natural and anthropogenic agents that gradually destroy the landscape and structures of this significant World Heritage Site. Therefore, conservation projects should be planned and applied that ensure the preservation of the village. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.
Environmental Earth Sciences (18666299)77(19)
Although Schmidt hammer test has been widely used for assessment of weathering state of rocks, its application for evaluation of rock durability remains rare. This study aims at investigating the performance of the Schmidt hammer test in the durability assessment of carbonate building stones against frost weathering. For this purpose, nine types of carbonate rocks were collected from various quarries of Iran and subjected to a series of tests including determination of petrographical, physical, mechanical, ultrasonic, and rebound hardness properties. Moreover, long-term weathering test of freeze–thaw, up to 100 cycles, were carried out and ultrasonic detection was used to detect the weathering-induced damages of rocks. In ultrasonic detections, ultrasonic parameters of maximum amplitude (Amax), spatial attenuation (αs), and compressional wave velocity (Vp) were determined before and after freeze–thaw tests and then their change rates were determined. The change rates of Amax, αs, and Vp including KA, Kα, and KP, respectively, were considered as the functions of the degree of the frost-induced damages of rocks, and consequently as indications of the rock durability. Results showed that there are close correlations between the Schmidt hammer rebound value (Rn) and KA, Kα, and KP. However, the correlation between Rn and KP was weaker than those between Rn and KA and Kα because of the disproportionate response of Vp to the rock deterioration. It was concluded that the Schmidt hammer test is capable to evaluate the durability of carbonate building stones and can be used for a rapid and onsite evaluation of rock durability at different quarry faces. Hence, it allows selecting more durable rocks for different applications in new constructions and also in replacement works in historical sites. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
Engineering Geology (00137952)208pp. 51-62
This paper presents a new method for the assessment of liquefaction potential, using the in-situ Dynamic Cone Penetrometer (DCP) test. The DCP is a lightweight and portable penetrometer that is considerably faster and cheaper than the boring equipment such as the Standard Penetration Test (SPT). In the present study, the liquefaction potential of liquefiable soils of six different sites was investigated using both the in-situ DCP test and the SPT. Following assessment of the liquefaction potential, the liquefaction potential index (LPI) was calculated for all six sites, again using both of these tests. Finally, the DCP test's capacity to assess liquefaction potential was evaluated by comparing the LPI values obtained from this test, as a new method, with the LPI values obtained from the SPT, as an index and popular method. The results showed that the DCP is equally as capable as the SPT in evaluating liquefaction potential. © 2016 Elsevier B.V.
Hashemi, M.,
Nikudel, M.R.,
Hafezi moghaddas n., N.H.,
Khamehchiyan m., Arabian Journal of Geosciences (discontinued) (18667538)7(6)pp. 2339-2352
A broad assessment of the geological, sedimentological, and geotechnical characteristics of the coastal Holocene sediments of Anzali Area (North Iran) was made to provide a useful guide for development, planning, and construction. Based on the sedimentological and geotechnical properties of the sediments, three engineering geological units as Upper Sandy Zone (USZ), Middle Clayey Zone (MCZ), and Lower Sandy Zone (LSZ) were identified and introduced in the form of an engineering geological model. Then the engineering geological characteristics of the units of the model were analyzed and the main engineering geological problems associated with the deposits of each unit were identified. The results showed that USZ has high liquefaction potential, low bearing capacity, settlement susceptibility, and excavation problem; MCZ has low-bearing capacity as well as high settlement susceptibility and excavation problem; and LSZ has good geotechnical properties, then it poses few problems. © 2013 Saudi Society for Geosciences.
Hashemi, M.,
Nikudel, M.R.,
Khamehchiyan m., ,
Hafezi moghaddas n., N.H. pp. 77-83
The engineering geological conditions and geohazards of Sefidrud Delta were assessed using a stepwise approach. The approach included the geological, sedimentological and geotechnical studies of the area. First of all the sedimentary environments of Delta and their associated deposits were identified. Investigation and assessment of engineering geological characteristics of these deposits revealed that the most Holocene deltaic deposits have poor geotechnical conditions. Most of these deposits are associated with geohazards including liquefaction, erosion and land subsidence. © Springer International Publishing Switzerland 2014.
Hashemi, M.,
Nikudel, M.R.,
Hafezi moghaddas n., N.H.,
Khamehchiyan m., Springer Geology (21979545)pp. 135-140
In this research a broad assessment of the geological, sedimentological and geotechnical characteristics of the coastal Holocene sediments of the Anzali Area was made and three engineering geological units as Upper Sandy Zone (USZ), Middle Clayey Zone (MCZ) and Lower Sandy Zone (LSZ) were identified. These units are the consequences of rapid sea-level fluctuations of the Caspian Sea in the Holocene. The engineering geological characteristics of these units were analyzed and the main engineering geological problems associated with sediments of each unit were identified. The results show that USZ has high liquefaction potential, low bearing capacity, settlement susceptibility and excavation problem. MCZ has low bearing capacity, high settlement susceptibility and excavation problem. LSZ that has good geotechnical properties poses few problems. © Springer-Verlag Berlin Heidelberg 2013.
