DBPapers
DOI: 10.5593/SGEM2014/B12/S2.078

MONITORING THE STABILITY OF THE ROCK MASS EXCAVATING OF UNDERGROUND PREMISES IN THE ORE BODY T1, JAMA BOR

S. Krstic, M. Ljubojev, V. Ljubojev, D. Tasic, Z. Stojanovic
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-08-7 / ISSN 1314-2704, June 19-25, 2014, Book 1, Vol. 2, 613-620 pp

ABSTRACT
Results of geotechnical observations and measurements that are continuously performed in mining are used to verify the projected geotechnical characteristics of the rock mass. In situ geotechnical measurements were performed on the excavated levels of the ore body T1 (K-110, K-130 and K-145). This work is part of project No. 33021 "Research and monitoring changes in the stress-strain state of rock mass in-situ around Undergrounds facilities to develop models with special reference to Krivelj tunnel River and Pine pit", which is funded by the Ministry of Education and Science Serbia. As part of the monitoring during the excavation of ore in ore bodies T1 and T2 from November 2013 to February 2014 the engineering-geological mapped underground excavations. The report was included in the mapping of underground excavation at elevations of K- 110, K-130, K-145 in the ore body T1. During the mapping of underground excavation at levels K-110, K-130 and K-145 ore body T1 was carried out a detailed survey of mechanical discontinuities in the rock mass. Based on 186 measurements of elements falling on the levels of K-110, K-130 and K-145 was performed statistical analysis of ore body T1. Graphical representation of engineering-geological mapping levels within the ore bodies is presented engineering-geological plans. Results executive engineering geological mapping of rock mass underground dug the ore body T1 (statistical analysis of the spatial orientation of the measured rupture), are partially mapped for each level and a total of mapping levels of the ore body T1. At the level of K-110, statistical analysis of data sampled three systems of cracks: EP1 24/70, EP2 17/47 and EP3 41/86. Cracks are mainly with plaster, rarely clay infill width of 2-5 mm, often with visible traces of movement (stretch marks). The meter area of observation is flat. A lot of present and minor cracks unfilled, rough walls, irregular schedules. There was one mylonitization zone along the fault with intensely degraded rock mass. They appear decametric zone large fissure of the rock mass. The level of K- 130, Statistical analysis identifies four systems of cracks: EP1 126/34, EP2 42/49, EP3 205/50 and EP4 322/75. The cracks are filled in with the dominant form of gypsum and clay widths up to 2 cm. It is often observed traces of movement (stretch marks). The participants were wider zone (zone large fissure) andesite in which there are fissures filled with clay. At the level K -145 Statistical analyses identifies four systems of cracks: EP1 187/70, EP2 143/43, EP3 15/70 and EP4 69/57. Cracks are generally tight with filling in the form gypsum and subordinate pyrite, up to 1 cm. There are also cracks filled with plaster and clay with visible traces of movement (stretch marks). Characteristic is the presence of faulting zone (width of up to 4 m), as well as the the ceiling of the underground excavation. In general, the geological structure of the rock mass in the studied horizons largely homogeneous (andesite). Andesite massif is commonly silicified. In the areas of large fissures of the rock mass of hydrothermal alteration is the most common sulfatization (gypsum and/or anhydrite), while rarely present kaolinization and piritization. Results RMR rock mass classification defines the rock mass of underground excavation of the ore body in the T1 class III (moderate rock).

Keywords: stability of the rock mass, geotechnical observations, in situ the measurements, underground premises