In-situ stress measurement in the Carnmenellis granite—I. Overcoring tests at South Crofty mine at a depth of 790 m

摘要: Abstract A programme of overcoring rock stress measurement was conducted at South Crofty mine, Camborne, a depth 790 m in the Carmenellis granite to obtain information required for Camborne School Mines (CSM) hot dry (HDR) Geothermal Energy Research Programme Rosemanowes quary Cornwall, U.K. The measurements were undertaken an independent confirmation magnitudes measured by hydraulic fracturing quarry and indication directions. Before tests undertaken, geological tectonic setting two sites reviewed it concluded that regimes should be similar. Both Commonwealth Scientific Industrial Organisation (CSIRO) Australia United States Bureau (USBM) designed overcoming systems used, with local contractor providing drilling services. total six CSIRO seven USBM successfully completed separate nearly horizontal boreholes 100° azimuth difference. Agreement between good. mean tensor determined from four best as follows (dip positive below horizontal). It is considered significant anisotropy must due forces Alpine orogeny, likely principal directions are similar Crofty.