Project schedule

The research is carried out in the area of the working face of drift SP-47 and in the adjacent rock massif to a depth of about 5 m. The project, particularly in the first year of its implementation, requires more technical work underground, combined with the investigation of the locality on the surface. The investigation also includes the foreground of the working face; so that the area of the drift face and its foreland was cleaned down to the fresh hard rock and subsequently the azimuth of fractures and faults was mapped in detail.
According to the above schedule about pilot boreholes of 76 mm diameter were drilled to study the rock environment. The site for the central borehole for heater was selected basing on acquired data on fractures and faults network, and one of the five pilot boreholes was used as a preboring for large-diameter borehole. A heat source was placed in this borehole during the progress of research. The pre-drilled borehole was extended to a length of 10 m, for proximate monitoring of more distant rock environment. By the end of 2012 a few series of ca 3 - 10 m long drill holes for monitoring purposes were drilled to study the characteristics related to:
- thermodynamics
- hydrodynamics
- geomechanics
- microseismicity
The grid of monitoring boreholes is designed and implemented depending upon the position of the central borehole. Some boreholes intended for the study of hydrodynamics are in relation to the horizontal plane inclined so that they are flooded with water. In contrast, the monitoring boreholes intended to investigate geomechanics and thermodynamics are inclined under such an angle so that they are spontaneously drained. The majority of the monitoring boreholes in relation to the vertical plane are orientated perpendicular to the face of the drift. Some of them are fanned out so that they ensure access to study rocks at greater distances away from the central borehole even in the case when the face is of limited dimensions. The real instrumentation allowing studying the distribution of heat in drift SP-47 were determined according to the dominant structural elements identified during the mapping stage (e.g., fissures and fractures network, filling of fissures or linear arrangement of minerals) and numerical simulation of the experiment.
A heater ca 50 cm long and about 80 cm in diameter was placed in the large-diameter borehole 2,2 m long, the rest of the hole were sealed. Measuring sensors connected to the monitoring network of the Czech Technical University were installed in monitoring boreholes for continuous electronic data collection. A cyclic thermal load of rocks is simulated by repeated heating (to ~ 90 ° C) and cooling (shutting down the heat source). Duration of one cycle of heating-cooling based on numerical simulations is tentatively assumed to last three months. The duration of individual cycles are specified according to the progress and results of the experiment. Monitoring boreholes are used for application of non-destructive measuring methods, particularly for the monitoring of hydraulic, geotechnical, thermodynamic and microseismic data. The collection of these data has been taken place from the beginning of heating until the scheduled end of the project (11-12/2014).
All information are incorporated into analogous mathematical models, specialized in issues of thermodynamics, hydrogeology and geomechanics. Each model is updated during the research process by newly acquired data and modified and tuned in accordance with the measured values.
Geology of the wider area around the Josef adit is an integral part of the project and is related to structural mapping that has been scheduled to be undertaken in 2012 and 2013.