In situ stress determination from excavation-induced stress by the compact conical-ended borehole overcoring method

0462327 - ÚGN 2017 RIV GB eng C - Conference Paper (international conference)
Hastíková, Alice - Kolcun, Alexej - Staš, Lubomír - Koníček, Petr
In situ stress determination from excavation-induced stress by the compact conical-ended borehole overcoring method.
Rock Mechanics and Rock Engineering: From the Past to the Future. London: CRC Press, Taylor and Francis Group, 2016 - (Ulusay, R.; Aydan, Ö.; Gercek, A.; Hindistan, H.; Tuncay, E.), s. 1203-1206. Volume 2. ISBN 978-1-138-03265-1.
[EUROCK 2016 - 2016 ISRM International Symposium. Cappadocia (TR), 29.08.2016-31.08.2016]
R&D Projects: GA MŠMT(CZ) LO1406; GA MŠMT ED2.1.00/03.0082
Institutional support: RVO:68145535
Keywords : in situ stress determination * excavation-induced stress * compact conical-ended borehole overcoring method (CCBO instrument)
OECD category: Mining and mineral processing

The Compact Conical Borehole Overcoring (CCBO) method originally developed in Japan to
determine stress in rock has been widely used by the Institute of Geonics, Czech Academy of Sciences. Only one borehole is required to install the CCBO instrument, measure strains and determine the full stress tensor in rock mass. To determine the pre-mining stress around the circular tunnel in undisturbed hard rock, the measurement requires a borehole of certain length to install the CCBO cell in location where the excavation does not affect the stress field.To reduce the drilling and installation costs, the Institute is developing new theoretical solutions for a short borehole strain measurement method enabling the CCBO cell installation closer to the circular tunnel. The
proposed semi-analytical approach uses the short borehole strain measurement results, theoretical calculations of stress distribution in the elastic medium around the circular tunnel and numerical modelling, to back analyze the probable pre-mining stress tensor. This approach enables determination of pre-mining stress obtained from the short borehole strain measurements in excavation-induced zone around underground opening. Discussed here are the theoretical calculation methods, numerical modelling results and a practical example of the pre-mining stress determination from the short borehole strain measurements using the CCBO instrument.
Permanent Link: http://hdl.handle.net/11104/0261800