Using of shaped conical borehole bottom to determination of the stress tensor changes induced by changing of geomechanical situation is described in this paper. The measured strain changes on gauge probe are caused not only by the stress changes evocateg by progress of long wall. The some deformation started imediatelly after instalation when the long wal didn't move. In paper are discussed the eventu alities of this phenomenon too., Lubomír Staš, Kamil Souček and Jaromír Knejzlík., and Obsahuje bibliografické odkazy
Compact conical strain gauge probe for borehole over-coring rock massif stress measurement (CCBO), based on experiences of K. Sugavara and Y. Obara, has been developed in Institute of Geonics ASCR, v.v.i. from 2004. First generation of CCBO is equipped by simple electronic circuit which requires continuous communication with control computer in the course of measurement. Prototypes of this type probes are used for long term stress changes monitoring induced by longwall advancement in mine. Solving of continuous data communication through rotating drilling tool filled by wash water in course of over-coring is very difficult technical task, which is not possible to solve in terms of grant project. To avoid this problem a development of second generation of CCBO equipped by microprocessor and internal data logger was initialised. Simplified modification of CCBO is developed as a probe for long-term monitoring of rock massif stress changes (Compact Conical Ended Borehole Monitoring - CCBM). Design of both models probes, discussion of measurement errors and technique of sensitivity self-calibration is described., Jaromír Knejzlík, Zdeněk Rambouský, Kamil Souček and Lubomír Staš., and Obsahuje bibliografii