Abstract
In order to elucidate the mechanism of hydraulic fracturing in sandy ground, we investigate the relation among the hydrofracturing pressure, the confining pressure and the permeability of sand through the injection tests on several kinds of sands, including the cemented sands as well as the cohesionless sands. The result is the following equation.
P′f=mσ′3+σt+R
P′f: hydrofracturing pressure, m: constant (1<=m<=2)
σ′3: confining pressure, σt: tensile strength
R: resistance of crack progression
The value of R depends upon the permeability of sands and increases as the permeability increases.
