Document Type : Original Research Paper


Department of Geology, Yazd University, Yazd, Iran


Due to the challenge of finding identical rock samples with varying grain sizes, investigating the impact of texture on rock material has been given less attention. However, macroscopic properties such as compressive strength, tensile strength, and modulus of elasticity can indicate microscopic properties like intergranular resistance properties influence rock fracture toughness. In this work, both the experimental and numerical methods are used to examine the effect of grain size on the mechanical properties of sandstone. Uniaxial compressive strength and indirect tensile tests are conducted on sandstone samples with varying grain sizes, and the particle flow code software is used to model the impact of grain dimensions on intergranular properties. Flat joint model is applied for numerical modeling in the particle flow code© software. The aim of this work is to validate the numerical model by peak strength failure and stress-strain curves to determine the effect of grain size on the mechanical behavior. The results show that increasing grain size significantly decrease compressive strength, tensile strength, and modulus of elasticity. The impact of the change in grain size is more significant on compressive strength than on the other two properties. The correlation coefficient for tensile strength and grain size is R2 = 0.57, while for modulus of elasticity and grain size, it is R2 = 0.79. The PFC software helps calibrate intergranular properties, and investigate the effect of changing grain size on these properties. Overall, this study offers valuable insights into the relationship between the grain size and the mechanical properties of sandstone, which can be useful in various engineering applications, especially in petroleum geo-mechanics.


[1]. Sultan Shah, K., Mohd Hashim, M.H.B., Rehman, H.U., and Ariffin, K.S.B. (2022). Evaluating microscale failure response of various weathering grade sandstones based on micro-scale observation and micro-structural modelling subjected to wet and dry cycles. Journal of Mining and Environment, 13 (2): 341-355.
[2]. Shah, K.S., Mohd Hashim, M.H., Rehman, H., and Ariffin, K.S. (2021). Application of Stochastic Simulation in Assessing Effect of Particle Morphology on Fracture Characteristics of Sandstone. Journal of Mining and Environment, 12(4): 969-986.
[3]. Fattahi, H. (2020). A New Method for Predicting Indirect Tensile Strength of Sandstone Rock Samples. Journal of Mining and Environment, 11(3): 899-908.
[4]. Shah, K.S., Mohd Hashim, M.H., and Ariffin, K.S. (2021). Monte Carlo Simulation-based Uncertainty Integration into Rock Particle Shape Descriptor Distributions. Journal of Mining and Environment, 12 (2): 299-311.
[5]. Golewski, G.L. (2023). Combined Effect of Coal Fly Ash (CFA) and Nanosilica (nS) on the Strength Parameters and Microstructural Properties of Eco-Friendly Concrete. Energies, 16 (1): 452.
[6]. Golewski, G.L. and Szostak, B. (2022). Strength and microstructure of composites with cement matrixes modified by fly ash and active seeds of CSH phase. Structural Engineering and Mechanics, 82 (4): 543-556.
[7]. Golewski, G.L. (2022). An extensive investigations on fracture parameters of concretes based on quaternary binders (QBC) by means of the DIC technique. Construction and Building Materials, 351, 128823.
[8]. Wang, J., Song, Z., Zhao, B., Liu, X., Liu, J., and Lai, J. (2018). A study on the mechanical behavior and statistical damage constitutive model of sandstone. Arabian Journal for Science and Engineering, 43, 5179-5192.
[9]. Hosseini, M. and Khodayari, A.R. (2019). Effect of freeze-thaw cycle on strength and rock strength parameters (A Lushan sandstone case study). Journal of Mining and Environment, 10 (1): 257-270.
[10]. Utili, S. and Nova, R.O.B.E.R.T.O. (2008). DEM analysis of bonded granular geomaterials. International Journal for Numerical and Analytical Methods in Geomechanics, 32 (17): 1997-2031.
[11]. Ding, X., Zhang, L., Zhu, H., and Zhang, Q. (2014). Effect of model scale and particle size distribution on PFC3D simulation results. Rock mechanics and rock engineering, 47, 2139-2156.
[12]. Nemat-Nasser, S. (1986). Overall stresses and strains in solids with microstructure. Modelling Small Deformations of Polycrystals, 41-64.
[13]. Külekçi, G., Vural, A., and Aliyazıcıoğlu, Ş. (2022). Assessment of Excavability Classification in A Limestone Quarry: A Case Study from Bayburt, Türkiye. Iranian Journal of Earth Sciences. 14 (4).
[14]. Kulekci, G., Yilmaz, A. O., and Cullu, M. (2021). Experimental investigation of usability of construction waste as aggregate. Journal of Mining and Environment, 12 (1): 63-76.
[15]. Kahraman, S.A.İ.R. and Alber, M. (2008). Triaxial strength of a fault breccia of weak rocks in a strong matrix. Bulletin of engineering geology and the environment, 67, 435-441.
[16]. Amann, F., Kaiser, P., and Button, E.A. (2012). Experimental study of brittle behavior of clay shale in rapid triaxial compression. Rock Mechanics and Rock Engineering, 45, 21-33.
[17]. Zhang, Y., Shao, J.F., Xu, W.Y., Zhao, H.B., and Wang, W. (2015). Experimental and numerical investigations on strength and deformation behavior of cataclastic sandstone. Rock Mechanics and Rock Engineering, 48, 1083-1096.
[18]. Cundall, P. A., Potyondy, D. O., and Lee, C. A. (1996, September). Micromechanics-based models for fracture and breakout around the mine-by tunnel. In proceedings, international conference on deep geological disposal of radioactive waste, Winnipeg. Edited by JB Martino and CD Martin. Canadian Nuclear Society, Toronto (pp. 113-122).
[19]. Hazzard, J.F. and Young, R.P. (2000). Simulating acoustic emissions in bonded-particle models of rock. International Journal of Rock Mechanics and Mining Sciences, 37 (5): 867-872.
[20]. Fakhimi, A., Carvalho, F., Ishida, T., and Labuz, J. F. (2002). Simulation of failure around a circular opening in rock. International Journal of Rock Mechanics and Mining Sciences, 39 (4): 507-515.
[21]. Diederichs, M.S. (2003). Manuel rocha medal recipient rock fracture and collapse under low confinement conditions. Rock Mechanics and Rock Engineering, 36, 339-381.
[22]. Hazzard, J.F. and Young, R. P. (2004). Dynamic modelling of induced seismicity. International journal of rock mechanics and mining sciences, 41 (8): 1365-1376.
[23]. Fakhimi, A., Riedel, J.J., and Labuz, J.F. (2006). Shear banding in sandstone: Physical and numerical studies. International Journal of Geomechanics, 6 (3): 185-194.
[24]. Wanne, T.S. and Young, R.P. (2008). Bonded-particle modeling of thermally fractured granite. International Journal of Rock mechanics and mining Sciences, 45 (5): 789-799.
[25]. Zhao, Z. (2013). Gouge particle evolution in a rock fracture undergoing shear: a microscopic DEM study. Rock Mechanics and Rock Engineering, 46, 1461-1479.
[26]. Khazaei, C., Hazzard, J., and Chalaturnyk, R. (2015). Damage quantification of intact rocks using acoustic emission energies recorded during uniaxial compression test and discrete element modeling. Computers and Geotechnics, 67, 94-102.
[27]. Ozturk, H. and Altinpinar, M. (2017). The estimation of uniaxial compressive strength conversion factor of trona and interbeds from point load tests and numerical modeling. Journal of African Earth Sciences, 131, 71-79.
[28]. He, J. and Afolagboye, L. O. (2018). Influence of layer orientation and interlayer bonding force on the mechanical behavior of shale under Brazilian test conditions. Acta Mechanica Sinica, 34, 349-358.
[29]. Yin, P.F. and Yang, S.Q. (2019). Discrete element modeling of strength and failure behavior of transversely isotropic rock under uniaxial compression. Journal of the Geological Society of India, 93, 235-246.
[30]. Zhou, C., Karakus, M., Xu, C., and Shen, J. (2020). A new damage model accounting the effect of joint orientation for the jointed rock mass. Arabian Journal of Geosciences, 13, 1-13.
[31]. Bahaaddini, M., Hagan, P.C., Mitra, R., and Hebblewhite, B.K. (2015). Parametric study of smooth joint parameters on the shear behaviour of rock joints. Rock Mechanics and Rock Engineering, 48, 923-940.
[32]. Zhao, W., Huang, R., and Yan, M. (2015). Study on the deformation and failure modes of rock mass containing concentrated parallel joints with different spacing and number based on smooth joint model in PFC. Arabian journal of geosciences, 8, 7887-7897.
[33]. Huang, D., Wang, J., and Liu, S. (2015). A comprehensive study on the smooth joint model in DEM simulation of jointed rock masses. Granular Matter, 17, 775-791.
[34]. Wang, T., Xu, D., Elsworth, D., and Zhou, W. (2016). Distinct element modeling of strength variation in jointed rock masses under uniaxial compression. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2, 11-24.
[35]. Chong, Z., Li, X., Hou, P., Wu, Y., Zhang, J., Chen, T., and Liang, S. (2017). Numerical investigation of bedding plane parameters of transversely isotropic shale. Rock Mechanics and Rock Engineering, 50, 1183-1204.
[36]. Chong, Z., Li, X., and Hou, P. (2019). Experimental and numerical study of the effects of layer orientation on the mechanical behavior of shale. Arabian Journal for Science and Engineering, 44, 4725-4743.
[37]. Huan, J. Y., He, M. M., Zhang, Z. Q., and Li, N. (2020). Parametric study of integrity on the mechanical properties of transversely isotropic rock mass using DEM. Bulletin of Engineering Geology and the Environment, 79, 2005-2020.
[38]. Lei, B., Li, H., Zuo, J., Liu, H., Yu, M., and Wu, G. (2021). Meso-fracture mechanism of Longmaxi shale with different crack-depth ratios: experimental and numerical investigations. Engineering Fracture Mechanics, 257, 108025.
[39]. Ghorbani, M. (2013). The economic geology of Iran. Mineral deposits and natural resources. Springer, 1-450.
[40]. Ghorbani, M. (2021). The geology of Iran: tectonic, magmatism and metamorphism. Springer International Publishing.
[41]. Emami Meybodi, E. and Jalali, S. M. E. (2015). Estimation of Fragmentation on Geometrical Viewpoint. Journal of Analytical and Numerical Methods in Mining Engineering, 5 (9): 51-61.
[42]. Ghorbani, M. (2019). Lithostratigraphy of Iran (p. 274). Cham: Springer.
[43]. Emami Meybodi, E., Hajibagheri Foroshani, J., and Kargaran Bafghi, F. (2022). Numerical modeling for Selection of appropriate tunneling method in S station of Isfahan subway.  11 (29): 27-40.‎
[44]. Meybodi, E. E., Hussain, S. K., Torabi-Kaveh, M., and Ali, S. (2022). Role of karstic features in instability of the wall of an open-pit mine (case study: Sadat Sirize Iron Mine, Iran). Carbonates and Evaporites, 37 (3): 52.
[45]. ASTM, D. (1995). 2938, Standard test method for unconfined compressive strength of intact rock core specimens. ASTM International, West Conshohocken, PA.
[46]. Bieniawski, Z.T., and Hawkes, I. (1978). Suggested methods for determining tensile strength of rock materials. International Journal of Rock Mechanics and Mining Sciences, 15 (3): 99-103.
[47]. Pirhooshyaran, M. R. and Nikkhah, M. (2022). Hydraulic fracture patterns in fractured rock mass using coupled hydromechanical modeling in the bonded particle model. Modeling Earth Systems and Environment, 1-14.
[48]. Emami Meybodi, E., Hussain, S. K., Fatehi Marji, M., and Rasouli, V. (2022). Application of Machine Learning Models for Predicting Rock Fracture Toughness Mode-I and Mode-II. Journal of Mining and Environment, 13 (2): 465-480.
[49]. Yang, S. Q., Tian, W. L., Huang, Y. H., Ranjith, P. G., and Ju, Y. (2016). An experimental and numerical study on cracking behavior of brittle sandstone containing two non-coplanar fissures under uniaxial compression. Rock Mechanics and Rock Engineering, 49, 1497-1515.
[50]. Emami Meybodi, E., Hussain, S. K., and Fatehi Marji, M. (2023). Experimental Evaluation and Discrete Element Modeling of Shale Delamination Mechanism. Journal of Mining and Environment, 14 (1): 259-276.
[51]. Emami Meybodi, E., DastBaravarde, A., Hussain, S. K., and Karimdost, S. (2023). Machine-learning method applied to provide the best predictive model for rock mass deformability modulus (E m). Environmental Earth Sciences, 82 (6): 149.
[52]. Brown, E. T. and Hoek, E. (1980). Underground excavations in rock. CRC Press.
[53]. Hondros, G. (1959). The evaluation of Poisson's ratio and the modulus of materials of a low tensile resistance by the Brazilian (indirect tensile) test with particular reference to concrete. Aust. J. Appl. Sci., 10, 243-264.
[54]. Barton, N. (2013). Shear strength criteria for rock, rock joints, rockfill and rock masses: Problems and some solutions. Journal of Rock Mechanics and Geotechnical Engineering, 5 (4): 249-261.
[55]. Irwin, G.R. (1957). Analysis of stresses and strains near the end of a crack traversing a plate.
[56]. Jin, Y., Yuan, J., Chen, M., Chen, K. P., Lu, Y., and Wang, H. (2011). Determination of rock fracture toughness K IIC and its relationship with tensile strength. Rock mechanics and rock engineering, 44, 621-627.
[57]. Sun, W., Du, H., Zhou, F., and Shao, J. (2019). Experimental study of crack propagation of rock-like specimens containing conjugate fractures. Geomechanics and Engineering, 17 (4): 323-331.