تعيين فشار شكست هيدروليكي خاك با استفاده از سلول پيشرفته ي تحكيم

STUDY OF HYDRAULIC FRACTURING IN CORE OF EARTH AND ROCK-FILL DAMS

Hydraulic fracturing can be described as the conditions leading to creation and propagation of cracks of fissures in soil mass as a results of excessive fluid pressure. In this paper, based on Moher-Columb criteria for shear mode and maximum tensile strength criteria for tensile mode, the hydraulic fracturing has been predicted with respect to the soil properties. Theoretical equations have been developed implying both total and effective stress. A new technique for hydraulic fracturing tests was developed based on the use of hollow cylindrical specimens prepared with a standard procedure. The results of the experimental study were compared with the hydraulic fracturing pressure derived from theoretical solution. It has been determined that in low confining pressure, tensile failure occurred rather than shear failure and in high confining pressure, failure was observed in shear mode. The linear relation between hydraulic fracture pressure and confining pressure was also confirmed by experimental results.