The extension of a physical modeling technique utilizing rock-simulants and simulated blast loading to model propagation of dilational waves through fluid-saturated fractured rock masses will be evaluated. Rock-simulants, with negligible matrix permeability, will be developed for specimen preparation. A step-by-step casting procedure will be employed to simulate jointing and bedding planes. Attempts will be made to model the shape and duration of the load rise time curves expected at depth due to free-field nuclear detonation. A unique loading technique for simulating attenuated dilational waves at depth, which utilizes a high velocity, rail driven tow sled, will be evaluated. Mathematical expressions for deter mining the mass and speed of the sled to give the required impulse force, as well as the shape and material properties of the sled to give the duration of impulse force, will be derived and systematically evaluated. Most of the research effort in phase I will be concentrated towards scaling the impulse force and development of a "rock simulant" with low matrix permeability. The proposed physical modeling study will provide a powerful approach for understanding the dynamic response of fluid-saturated fractures and provide a unique tool for code validation.
