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Evaluation of rock burst phenomena in tunnel sites using experimental and semi-experimental methods – A case study: Haji-Abad tunnel in Hormozgan province
M.sc. Behrooz Margan, Dr. Davood Fereidooni,
Volume 18, Issue 1 (5-2024)
Abstract
In this research, various aspects of the rock burst phenomenon in the Haji-Abad tunnel site in the Hormozgan province have been discussed. Considering that the tunnel site is located in an active tectonized environment in terms of geological conditions and the depth of the tunnel in some parts reaches more than 100 to 253 m, and also considering the variety of rocks in the tunnel site, which are massive rocks with high strength up to broken fault zones, the importance of studying and investigating the phenomenon of rock burst is very important for the safety of the labor force and equipment and the stability of the underground space. For this purpose, the Haji-Abad tunnel site has been divided into ten units of engineering geological conditions using the BGD method, which includes eight units T1 to T8 and two crashed zones Tf1 and Tf2. Then, using common experimental and semi-experimental methods, the phenomenon of rock burst in the tunnel site has been evaluated. In the experimental procedure, Goel et al.'s criterion was used, according to which the rock burst phenomenon does not occur in any of the tunnel units. Using semi-empirical methods, including the criterion of linear elastic energy of the tunnel site units in the range of very low to moderate rock burst phenomena and using the tangential stress criterion, the site units in the medium to very high range and based on the stress criteria of these units in the moderate to high range and finally, using the fragility criterion, all site units are placed in the range of high rock burst.

Engineering Geological Analysis and Modeling of Excavations in the medium depth, Venarch Manganese Mine (Qom)
Mohammad Zainali, Dr Mohammad Reza Asef, Dr Ruholah Nadri,
Volume 18, Issue 1 (5-2024)
Abstract
This paper investigates the application of geomechanical and geological engineering methods to determine the optimum working face width for the safe and efficient extraction of manganese ore extraction at the Venarch Mine (Qom Province, Central part of Iran). The underground workings on the west face (240m depth) present significant geotechnical challenges due to the presence of faults, clay seams, and loose rock layers. These features require careful careful stability analysis to ensure the safety and economic viability of the underground mining operation. This study uses three established methods for rock mass classification and stability assessment. The Rock Mass Rating (RMR) classification system, the Q-system (Barton), and the numerical analysis using Plaxis 3D software. A robust and data-driven approach to determining the optimum workshop width was achieved by employing a synergistic combination of these three methods, together with meticulous ground observations and expert engineering judgement. This framework offers a powerful tool for determining the optimal and safe workshop width for this sector of the mine. By capitalizing on the strengths of each methodology, this research aims to establish a data-driven and informed decision-making process to ensure a stable and economically viable approach.

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 (9-2024)
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.

Earthquake possibility space of Ahvaz city based on intuitionistic fuzzy theory
Dr Sasan Motaghed, Dr Marzieh Shamsizadeh, Dr Nasrolla Eftekhari,
Volume 18, Issue 3 (12-2024)
Abstract
In this study, we present the Seismic Hazard Possibility Space (SHPS) for the city of Ahvaz. To achieve this, we applied the intuitionistic fuzzy method to weigh the logic tree used in the hazard analysis and constructed the SHPS based on expert opinions regarding the degrees of membership and non-membership. Hazard disaggregation was performed by through the concept of intuitionistic fuzzy sets, leading to the development of an intuitionistic fuzzy of an Intuitionistic Fuzzy Logic Tree (IFLT). The SHPS includes both the degree of membership and non-membership for pathways contributing to hazard generation. The SHPS illustrates the acceptance, non-acceptance, and ambiguity associated with potential hazard values from an expert perspective, thus assisting analysts in selecting appropriate hazard values. According to the numerical results of our analysis in the Ahvaz region, the seismic hazard is located in an uncertainty (unacceptability) zone, indicating that experts have low confidence in the results of the probabilistic seismic hazard analysis (PSHA) for Ahvaz. In addition, the hazard is characterized by an "unconfident zone". This finding indicates that experts are fairly confident in the results of the analysis for Ahvaz. This finding implies that the models and parameters used in the PSHA for this region are not accepted by experts, and further efforts are needed to identify or develop appropriate models and accurate parameters specific to the area. In conclusion, this research demonstrates how intuitionistic fuzzy sets can be used to construct SHPS, providing a novel framework for quantifying uncertainty and expert opinion in hazard assessment.

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