Determination of In-Situ Stresses Around Underground Excavations by Means of Hydraulic Fracturing.

摘要

Laboratory tests have been conducted to determine the mechanical properties of Coeur d'Alene quartize and to establish whether this highly inhomogeneous,precracked variable rock is suitable for hydraulic fracturing as a method of in-situ stress measurement. It was found that basically the Coeur d'Alene quartzite is amenable to hydraulic fracturing testing. The rock has no consistent anisotropy,but is inhomogeneous with physical property variations depending on fabric changes and existence of fractures and mica inclusions. Hydrofracture direction is always perpendicular to the smallest horizontal stress notwithstanding rock condition. Field stress measurements in the Coeur d'Alene mines using the hydraulic fracturing technique are recommended. (Modified author abstract)