Shahrood University of Technology Journal of Mining and Environment 2251-8592 13 1 2022 01 01 Estimation of In-Situ Block Size Distribution in Jointed Rock Masses using Combined Photogrammetry and Discrete Fracture Network 175 184 2316 10.22044/jme.2022.11445.2129 EN M. Ghaedi Ghalini Department of Mining Engineering, Higher Education Complex of Zarand, Zarand, Iran M. Bahaaddini School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran Shahid Bahonar University of Kerman, Kerman, Iran M. Amiri Hossaini Mining and Geology Researches Department, Golgohar Mining and Industrial Company, Sirjan, Iran Journal Article 2021 12 01 Estimation of the in-situ block size is known as a key parameter in the characterization of the mechanical properties of rock masses. As the in-situ block size cannot be measured directly, several simplified methods have been developed, where the intrinsic variability of the geometrical features of discontinuities are commonly neglected. This work aims to estimate the in-situ block size distribution (IBSD) using the combined photogrammetry and discrete fracture network (DFN) approaches. To this end, four blasting benches in the Golgohar iron mine No. 1, Sirjan, Iran, are considered as the case studies of this research work. The slope faces are surveyed using the photogrammetry method. Then 3D images are prepared from the generated digital terrain models, and the geometrical characteristics of discontinuities are surveyed. The measured geometrical parameters are statistically analysed, and the joint intensity, the statistical distribution of the orientation, and the fracture trace length are determined. The DFN models are generated, and IBSD for each slope face is determined using the multi-dimensional spacing method. In order to evaluate the validity of the generated DFN models, the geological strength index (GSI) as well as the stereographic distribution of discontinuities in the DFN models are compared against the field measurements. A good agreement has been found between the results of the DFN models and the filed measurements. The results of this work show that the combined photogrammetry and DFN techniques provide a robust, safe, and time-efficient methodology for the estimation of IBSD.  https://jme.shahroodut.ac.ir/article_2316_e6ef986f61dd5bdb8dae50b73040b046.pdf