@article{MTMT:34234011, title = {Estimation of the Poisson's Ratio of the Rock Mass}, url = {https://m2.mtmt.hu/api/publication/34234011}, author = {Narimani Ghourtlar, Samad and Davarpanah, Seyed Morteza and Vásárhelyi, Balázs}, doi = {10.3311/PPci.22689}, journal-iso = {PERIOD POLYTECH CIV ENG}, journal = {PERIODICA POLYTECHNICA-CIVIL ENGINEERING}, volume = {68}, unique-id = {34234011}, issn = {0553-6626}, abstract = {The value of Poisson's ratio is a crucial parameter in rock mechanics and engineering for both intact rock and rock mass. Poisson's ratio has not gotten the attention it merits compared to other essential mechanical characteristics of intact rock and rock mass. Limited relationships exist between rock mass classification systems (such as RMR, RMQR, Q, and GSI) and Poisson's ratio. This paper provides a comprehensive review of models proposed by various researchers for estimating Poisson's ratio for rock mass. The different methods are compared, and new general equations are derived. The results indicate that the Poisson's ratio value of rock mass is inversely proportional to its quality and strength and depends on the Poisson's ratio value of the intact rock. Specifically, a linear equation is obtained using the RMR or GSI system, showing that the Poisson's ratio increases as the quality and strength of the rock mass decrease. The Q system has a logarithmic link between the rock mass quality and Poisson's ratio. It should be noted that the derived equations are applicable only under the assumption of a homogeneous isotropic rock mass.}, keywords = {STRESS; YOUNGS MODULUS; strength; Rock mass classification; Rock mass; Poisson's ratio}, year = {2024}, eissn = {1587-3773}, pages = {274-288}, orcid-numbers = {Vásárhelyi, Balázs/0000-0002-0568-1031} } @mastersthesis{MTMT:34738301, title = {Strength and deformation characteristics of rigid rocks under different conditions using experimental methods and statistical analyses}, url = {https://m2.mtmt.hu/api/publication/34738301}, author = {Davarpanah, Seyed Morteza}, publisher = {Budapest University of Technology and Economics}, unique-id = {34738301}, year = {2023} } @inproceedings{MTMT:34184044, title = {Characterization of Poisson’s ratio and Elastic Modulus of granitic rocks: from micro-crack initiation to failure}, url = {https://m2.mtmt.hu/api/publication/34184044}, author = {Narimani Ghourtlar, Samad and Davarpanah, Seyed Morteza and Kovács, László and Vásárhelyi, Balázs}, booktitle = {Proceedings of the ISRM 15th International Congress on Rock Mechanics and Rock Engineering & 72nd Geomechanics Colloquium}, unique-id = {34184044}, year = {2023}, pages = {2508-2513}, orcid-numbers = {Vásárhelyi, Balázs/0000-0002-0568-1031} } @article{MTMT:34093135, title = {Geological Strength Index Relationships with the Q-System and Q-Slope}, url = {https://m2.mtmt.hu/api/publication/34093135}, author = {Narimani Ghourtlar, Samad and Davarpanah, Seyed Morteza and Bar, Neil and Török, Ákos and Vásárhelyi, Balázs}, doi = {10.3390/su151411233}, journal-iso = {SUSTAINABILITY-BASEL}, journal = {SUSTAINABILITY}, volume = {15}, unique-id = {34093135}, abstract = {The Q-system and Q-slope are empirical methods developed for classifying and assessing rock masses for tunneling, underground mining, and rock slope engineering. Both methods have been used extensively to guide appropriate ground support design for underground excavations and stable angles for rock slopes. Using datasets obtained from igneous, sedimentary, and metamorphic rock slopes from various regions worldwide, this research investigates different relationships between the geological strength index (GSI) and the Q-system and Q-slope. It also presents relationships between chart-derived GSI with GSI estimations from RMR89 and Q' during drill core logging or traverse mapping. Statistical analysis was used to assess the reliability of the suggested correlations to determine the validity of the produced equations. The research demonstrated that the proposed equations provide appropriate values for the root mean squared error value (RMSE), the mean absolute percentage error (MAPE), the mean absolute error (MAE), and the coefficient of determination (R-squared). These relationships provide appropriate regression coefficients, and it was identified that correlations were stronger when considering metamorphic rocks rather than other rocks. Moreover, considering all rock types together, achieved correlations are remarkable.}, keywords = {MECHANICAL-PROPERTIES; Rock mass classification; Environmental Sciences; GREEN & SUSTAINABLE SCIENCE & TECHNOLOGY; Q-SYSTEM; Q-slope}, year = {2023}, eissn = {2071-1050}, orcid-numbers = {Török, Ákos/0000-0002-5394-4510; Vásárhelyi, Balázs/0000-0002-0568-1031} } @article{MTMT:33766973, title = {Variation of Elastic Stiffness Parameters of Granitic Rock during Loading in Uniaxial Compressive Test}, url = {https://m2.mtmt.hu/api/publication/33766973}, author = {Narimani Ghourtlar, Samad and Davarpanah, Seyed Morteza and Kovács, László and Vásárhelyi, Balázs}, doi = {10.3390/applmech4020025}, journal-iso = {APPLI MECH}, journal = {APPLIED MECHANICS}, volume = {4}, unique-id = {33766973}, abstract = {Any rock mechanics’ design inherently involves determining the deformation characteristics of the rock material. The purpose of this study is to offer equations for calculating the values of bulk modulus (K), elasticity modulus (E), and rigidity modulus (G) throughout the loading of the sample until failure. Also, the Poisson’s ratio, which is characterized from the stress–strain curve, has a significant effect on the rigidity and bulk moduli. The results of a uniaxial compressive (UCS) test on granitic rocks from the Morágy (Hungary) radioactive waste reservoir site were gathered and examined for this purpose. The fluctuation of E, G, and K has been the subject of new linear and nonlinear connections. The proposed equations are parabolic in all of the scenarios for the Young’s modulus and shear modulus, the study indicates. Furthermore, the suggested equations for the bulk modulus in the secant, average, and tangent instances are also nonlinear. Moreover, we achieved correlations with a high determination factor for E, G, and K in three different scenarios: secant, tangent, and average. It is particularly intriguing to observe that the elastic stiffness parameters exhibit strong correlation in the results.}, year = {2023}, eissn = {2673-3161}, pages = {445-459}, orcid-numbers = {Vásárhelyi, Balázs/0000-0002-0568-1031} } @article{MTMT:33581825, title = {Brittle-ductile transition stress of different rock types and its relationship with uniaxial compressive strength and Hoek–Brown material constant (mi)}, url = {https://m2.mtmt.hu/api/publication/33581825}, author = {Davarpanah, Seyed Morteza and Sharghi, Mohammad and Narimani Ghourtlar, Samad and Török, Ákos and Vásárhelyi, Balázs}, doi = {10.1038/s41598-023-28513-3}, journal-iso = {SCI REP}, journal = {SCIENTIFIC REPORTS}, volume = {13}, unique-id = {33581825}, abstract = {Rocks deformed at low confining pressure are brittle, which means that after peak stress, the strength declines to a residual value established by sliding friction. The stress drop is the variation between peak and residual values. But no tension reduction takes place at high confining pressure. A proposed definition of the brittle-ductile transition is the transition pressure at which no loss in strength takes place. However, studies that consider information about the brittle-ductile transition, the criterion's range of applicability, how to determine mi, and how confining pressures affect m i 's values are scarce. This paper aims to investigate the link between brittle-ductile transition stress, uniaxial compressive strength and Hoek–Brown material constant ( m i ) for different kinds of rock. It is essential to accurately determine the brittle-ductile transition stress to derive reliable values for m i . To achieve this purpose, a large amount of data from the literature was chosen, regression analysis was carried out, and brittle-ductile transition stress (σ TR ) was determined based on the combination of Hoek–Brown failure criteria and the recently used brittle-ductile transition stress limit of Mogi. Moreover, new nonlinear correlations were established between uniaxial compressive strength and Hoek–Brown material constant ( m i ) for different igneous, sedimentary and metamorphic rock types. Regression analyses show that the determination coefficient between σ TR and UCS for gneiss is 0.9, sandstone is 0.8, and shale is 0.74. Similarly, the determination coefficient between σ TR and m i for gneiss is 0.88. The correlation between Hoek–Brown material constant ( m i ) and σ TR was not notable for sedimentary and metamorphic rocks, probably due to sedimentary rocks' stratification and metamorphic ones' foliation.}, year = {2023}, eissn = {2045-2322}, orcid-numbers = {Török, Ákos/0000-0002-5394-4510; Vásárhelyi, Balázs/0000-0002-0568-1031} } @{MTMT:33571514, title = {Analytical and numerical investigation of the critical height of vertical slope}, url = {https://m2.mtmt.hu/api/publication/33571514}, author = {Besharatinezhad, Ali and Khodabandeh, Mohammad Ali and Narimani Ghourtlar, Samad and Davarpanah, Seyed Morteza and Tarifard Karvigh, Abolfazl and Török, Ákos and Vásárhelyi, Balázs}, booktitle = {Engineering problems in soft rocks}, unique-id = {33571514}, year = {2022}, pages = {512-520}, orcid-numbers = {Török, Ákos/0000-0002-5394-4510; Vásárhelyi, Balázs/0000-0002-0568-1031} } @inbook{MTMT:33571081, title = {Applicability of the recently proposed semi-empirical failure criterion for different rock types by using triaxial test data}, url = {https://m2.mtmt.hu/api/publication/33571081}, author = {Davarpanah, Seyed Morteza and Narimani Ghourtlar, Samad and Besharatinezhad, Ali and Khodabandeh, Mohammad Ali and Török, Ákos and Vásárhelyi, Balázs}, booktitle = {Engineering problems in soft rocks}, unique-id = {33571081}, abstract = {Defining the practical and proper rock failure criteria plays the most significant role in analysis and design in rock mechanics and rock engineering. Up to now, several failure criterions have been proposed for brittle rocks. Among them, Hoek-Brown failure criterion has received much attention and applied among the others for brittle rocks. The goal of this paper is to investigate the applicability of newly semi-empirical developed failure criterion inspired by Hoek-Brown failure criteria. To fulfil this aim, different triaxial test data from literature were selected and analysed for different rock types. Our obtained results prove the validity of recently proposed formulation for different investigated rock types.}, year = {2022}, pages = {355-362}, orcid-numbers = {Török, Ákos/0000-0002-5394-4510; Vásárhelyi, Balázs/0000-0002-0568-1031} } @article{MTMT:32916670, title = {Review on the mechanical properties of frozen rocks}, url = {https://m2.mtmt.hu/api/publication/32916670}, author = {Davarpanah, Seyed Morteza and Török, Ákos and Vásárhelyi, Balázs}, doi = {10.17794/rgn.2022.3.7}, journal-iso = {RUDARSKO GEOLOSKO NAFTNI ZBORNIK - MIN GEOL PETROL ENG BULL}, journal = {RUDARSKO GEOLOSKO NAFTNI ZBORNIK - MINING GELOLOGICAL PETROLEUM ENGINEERING BULLETIN}, volume = {37}, unique-id = {32916670}, issn = {0353-4529}, abstract = {The freezing technique has been employed for a long time to strengthen the mechanical properties of intact rock and rock mass; however, it has not received as much attention as it deserves. This paper thoroughly reviews the effect of freezing on the essential mechanical properties, including uniaxial compressive strength, tensile strength, and Young's modulus. The laboratory tests include the determination of density, ultrasound speed propagation, and strength parameters, such as uniaxial compressive strength, tensile strength, and Young's modulus. According to previously published results, the strength of different rocks such as marl, limestone, sandstone, tuff, granite, and marble increased significantly due to freezing when the samples were tested in frozen conditions. However, there is variation in strength increase based on rock type. It is outlined here that freezing increases rock strength by a factor of 4 in porous rock and by a factor of 1.8 in crystalline rock. Additionally, Young's modulus increases with a decrease in temperature; however, a further decrease in temperature from -10 to -20 degrees C has no effect on Young's modulus. Moreover, mathematical modelling for frozen rock has been reviewed comprehensively. It was found that porosity, the density of rock grains, density of water, residual unfrozen water content, minimum unfrozen water content at freezing point, material parameters, the initial temperature of rock, crystal size, orientation and alignment of minerals, and the loading rate are the most critical parameters that influence frozen rock strength.}, keywords = {MODEL; BEHAVIOR; PARAMETERS; WATER-CONTENT; DEFORMATION; YOUNGS MODULUS; uniaxial compressive strength; Young's modulus; sandstone; P-wave velocity; Geosciences, Multidisciplinary; Strength parameters; frozen rock}, year = {2022}, eissn = {1849-0409}, pages = {83-96}, orcid-numbers = {Török, Ákos/0000-0002-5394-4510; Vásárhelyi, Balázs/0000-0002-0568-1031} } @article{MTMT:32161987, title = {Studies on the Mechanical Properties of Dry, Saturated, and Frozen Marls Using Destructive and Non-destructive Laboratory Approaches}, url = {https://m2.mtmt.hu/api/publication/32161987}, author = {Davarpanah, Seyed Morteza and Sharghi, Mohammad and Tarifard Karvigh, Abolfazl and Török, Ákos and Vásárhelyi, Balázs}, doi = {10.1007/s40996-021-00690-z}, journal-iso = {IJST-T CIV ENG}, journal = {IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY-TRANSACTIONS OF CIVIL ENGINEERING}, volume = {46}, unique-id = {32161987}, issn = {2228-6160}, year = {2022}, eissn = {2364-1843}, pages = {1311-1328}, orcid-numbers = {Sharghi, Mohammad/0000-0002-5734-5347; Török, Ákos/0000-0002-5394-4510; Vásárhelyi, Balázs/0000-0002-0568-1031} }