The safe design of deep missile basing structures subjected to stress transients generated by surface disturbances such as nuclear or conventional explosions is a very important problem for J.S. national security interest. The propagation of surface disturbances through inhomogeneous, jointed, fractured, and layered geologic medium of the infinite domain is a very complex problem especially near deep underground openings/structures. The development of an optimum hybrid numerical scheme combining different numerical schemes of individual subdomains such as deep underground structure, thinlayer medium-structure interface, disturbed field near the opening/ structure, intact field away from the opening/structure, and boundary of infinite domain is essential for analysis of deep missile basing systems. Phase I investigation is to study the feasibility of an optimum hybrid numerical scheme combining the finite element, finite difference, district element, and boundary element/infinite element modeling techniques. successful completion of Phase I study will provide the feasibility of a unified and economical scheme as a tool to analyze deep underground structures subjected to surface or near surface nuclear bursts. This will provide the essential foundation for the development of an optimum unified hybrid numerical scheme, solution algorithm and a computer code for the analysis of deep missile basing systems.
