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Showing 5 results for Talkhablo
Effect of Texture on Crushability of Carbonate Sand in Northern Coasts of Persian Gulf
Sm Fatemiaghda, H Shahnazari, H Karami, M Talkhablou,
Volume 11, Issue 4 (Vol. 11, No. 4 Winter 1018 2018)
Abstract
Carbonate soils are different from silicate soils respect to their origination and engineering behavior. Particles of these soils are mainly residual or debris of sea animals or plants with large amount of calcium carbonate. They also may be chemical sedimentation of calcium carbonate over other soil particles in specific region of seas and oceans. The most important characteristic of these soils is the crushability of their aggregates under loading which is mainly due their shape and also small voids inside of them.  Crushability and subsequent volume changes in carbonate soils have caused many engineering problems in some geotechnical structures such as ...../files/site1/files/0Extended_Abstract5.pdf
Examination on the Rate of Weight Loss of Aggregates in Los Angeles Test in Different media A case study: South side of Daneh Khoshk and Damavand
Kazem Bahrami1, Seyed Mahmoud Fatemi Aghda, Ali Noorzad, Mehdi Talkhablou,
Volume 13, Issue 2 (Vol. 13, No. 2 2019)
Abstract
Aggregates are one of the high demand building materials in construction of structures and their characteristics have important effects on durability and permanence of projects. Abrasion resistance is one of the important features of aggregates that their utilization in concrete and asphalt are affected by texture and lithology of them. As rock consisted of harder minerals have higher abrasion resistance like igneous rocks, due to more siliceous minerals. More varieties in mineralogy compound usually lead to increase in aggregate abrasion. Aggregates that are contained of different minerals usually have less abrasion resistance. Porosity usually decreases the resistance abrasion. In addition to lithological properties, the environment where aggregates are deposited is important in determining resistance-related parameters of aggregates.
Rivers, alluvial fans, and taluses are the main environments where aggregates are deposited. Geological processes, such as weathering and particle movement may cause changes in natural aggregates, hence affecting their abrasion and impact resistance. Rock weathering can results in increasing porosity, producing minerals that are weaker in comparison to their original rock.
In the process of particles transport by stream water, weak parts of aggregates will be omitted. The present study is focused on the relationship between geology medium and the weight loss of aggregate in Los Angeles test. 
Methodology
Considering that lithology features in aggregates resistance against abrasion have an important role, in order to examine the effect of various geology environments in abrasion resistance of aggregates, the medium should be chosen having similar lithology. Therefore, the north of Damavand and the south of Daneh Khoshk anticline (north of Dire plain) were firstly chosen by using geology map, satellites images and field study. Damavand zone consists of trachyte and trachy-andesite volcanic rocks. These rocks cover the whole area around the Damavand peak. Also, Daneh Khoshk anticline is covered by thick Asmari formation. The selected environment are in the length of each other. Such that taluses feed alluvial fan and alluvial fans feed rivers. Samples were collected from different area of southern part of anticline. 10 river area, 12 alluvial fan and 6 taluses in the south-west area of Daneh Khoshk anticline (north of Dire plain) were chosen. Los Angeles test has been done according to standard A method ASTM D2216-10, 1990 on samples and the results were analyzed by analogous analyzer.
Results and discussion
Results show that porosity and micro-crack percentage increase, respectively in accumulated aggregate in river, alluvial fans and taluses areas. Also, porosity and micro-crack in various alluvial fans is different and is influenced by the area and length of main channel of alluvial fans’ catchment. The porosity decreases by the increase in the length of channel and area of alluvial fans’ catchment.
The percentages of aggregate weight loss in talus, alluvial fan and river areas decreases, respectively. Based on the obtained results, the lowest rates of weight loss belong to river environments (23.7 % in Daneh Khoshk and 42% in Damavand) whereas the highest rates of weight loss belong to taluses (49.3% in Daneh Khoshk and 48% in Damavand). The alluvial fans have an average state. Another noticeable point is the high weight loss in Los Angeles test in Damavand aggregate. Due to having harder mineral, igneous aggregate have more abrasion resistance, but this research illustrates that the weight loss resulting from Los Angeles test in these aggregates is high. This is because of virtues texture that weakness against the impact as well as their high porosity.
Conclusion
The result of this research indicates that the volume of aggregate weight loss in Los Angeles test is related to aggregate accumulation environment. The extent of aggregate abrasion resistance is lowest in talus medium and increases in alluvial fan and river environment, respectively. The difference in aggregate abrasion resistance in various areas result from geology process differences that applies to aggregates in various environment. The extent of caring particles in talus environment is very low and the type of movement is mass or sliding type in these media, micro-crack and weak parts remains within aggregates. The surface of micro crack is weak such that breaks easily in Los Angeles test due to the pressure results from the impact of aggregate, as well as the impact of steel ball on aggregate leading to aggregate breakages. Aggregates move more distances in alluvial fan and river. Aggregate strike together in riverbed and alluvial fan yielding to aggregates breakages from micro-cracks. As the movement distance increases, aggregates approach more to intact rock. During the particles move, the weathered and weak parts are damaged by aggregate abrasion to riverbeds and alluvial fan, and more resistant and harder aggregates remain. As the water current increases, the aggregates impact each other harder, more resistant micro-crack breakages and this change leads to decrease the weight loss in Los Angeles test.
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Effects of Texture and Carbonate Content on Internal Friction Angle for Soils of Northern Coasts of Persian Gulf
Habib Shahnazari, Mahmoud Fatemiaghda, Hamid Reza Karami, Mehdi Talkhablou,
Volume 14, Issue 5 ( English articles 2020)
Abstract

The present work is conducted to investigate the effect of texture and carbonate content on internal friction angle of carbonate soils. Carbonate soils are majorly found in the bed of shallow waters and also offshores in tropical regions. Recently there is a huge construction projects including oil and gas extraction platform and facilities, harbors, refineries, huge bridges and other big construction projects in many offshore and onshore areas around the world. One of these area is located on southern part of Iran. We collected soil samples from different parts of northern coasts of Persian Gulf, then the following experiments were performed, carbonate content, three-dimensional grain size, angularity, relative density & direct shear. The results showed that the average of internal friction angle of carbonate soil is higher respect to known silicate sands. This angle is affected by effective grain size, grain angularity, and calcium carbonate content. Based on the experimental results of this study, one of the results was that the internal friction angle of carbonate soils decreases as their effective size of soil aggregates increases.
 


Investigating the effective parameters on the stability system of tunnels using the Rock Engineering System (RES) method
Mehdi Talkhablou, Seyed Mahmoud Fatemi Aghda, Habibulah Heidari Renani,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
The stabilization of underground spaces is one of the most challenging topics in engineering geology. There are several methods to determine the type of tunnel stabilization system, but most of these methods have several weaknesses. Therefore, the development of a method that comprehensively considers almost all parameters influencing tunnel stability and their interdependencies has not received sufficient attention. The aim of this research is to investigate the parameters influencing the stability of tunnels using the rock mechanics system method. In this paper, 6 tunnels with different geological characteristics were selected. The effective parameters on the primary stabilization of these tunnels were coded using the ESQ method. Subsequent analyses were performed using the RES rock engineering system method to estimate and evaluate the optimal tunnel stabilization system. The results showed that parameters such as weathering of the joint surface, backfill and joint spacing played a more effective role than other parameters. For comparison, the analyses were also carried out using the RMR rock mass ranking method. The comparison between the results of the RES and RMR methods showed that the results of the RES method are in better agreement with the actual tunnel conditions and the shotcrete thickness of the proposed stabilization system of the studied tunnels. Since there is no limit to the number of input parameters in this method and, on the other hand, the mutual influence of the parameters on each other is considered, the relationships obtained from the RES method in this research can be effectively used in engineering projects along with other methods.
 

Assessment of alkali-silica reaction (ASR) in active aggregates using concrete petrography and the dri index
Seyyed Mahmoud Fatemi Aghda, Seyyed Sara Mousavi Herati, Mehdi Talkhablo, Amir Maziar Raeis Ghasemi,
Volume 18, Issue 2 (Summer 2024)
Abstract
The alkali-silica reaction of aggregates is one of the most significant factors in the destruction of concrete structures worldwide. This is due to chemical reactions between alkaline fluids in concrete voids and active silica minerals present in some aggregates. Considering that many physical, chemical and mechanical properties of concrete are related to aggregates, the role of aggregates in concrete is crucial. This research aims to investigate the compatibility of aggregate petrographic studies and accelerated prismatic mortar testing in predicting the reactivity of aggregates and determining the intensity of aggregate reactivity using the DRI index (a semi-quantitative complementary petrographic analysis). The study was carried out on laboratory samples of aggregates from mines around Tehran, using the ASTM C295, ASTM C1260 and ASTM C856-4 tests. The results showed that pyroclastic aggregates, which include sandy tuff, crystalline tuff (dacitic andesite) and glassy tuff, have the potential to cause an alkali-silica reaction due to their glassy background and microcrystalline silica. During the alkaline reaction tests of the aggregates, evidence of gel was found in cracks, holes and cement paste. In addition, the DRI index showed that the fine aggregates of both study areas were in the "slightly damaged" category and the coarse aggregates were in the "severely damaged" category.

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