SCALE AND TIME EFFECTS IN HYDRAULIC FRACTURING.

An experimental study was conducted to determine the effects of scale and time on hydraulic fracturing in compacted samples of Teton Dam silt and Pittsburg silty clay. A theory was developed to show how size of opening, time of pressurizing opening, and soil permeability are related to the occurrence of hydraulic fracturing. Finite element analyses were used to investigate the possible effects of nonlinear soil behavior. Both experimental and theoretical studies show that hydraulic fracturing can be initiated by seepage-induced forces without the presence of a preexisting flaw in the soil. Refs.