Advances for modelling of geological materials

Geologic material models have been developed, based on static triaxial data, that improve hydrocode modelling capabilities in the assessment of Kinetic Energy warheads against soil and concrete targets. Recent work has demonstrated that the flow and failure of geological materials under confinement are strongly dependent on the load path and strain rate. This paper will describe test methods that are currently being developed by DERA to generate new models that are also predictive for shaped charge, Explosively Formed Projectile and contact explosive loading against such targets. Existing GREAC (Gauged REACtive Confinement) and Hoek cell methodologies have been used to determine the physical states that control the path dependent response of concrete. The variation of the state variable has been determined under different hydrostatic loading conditions and this behaviour will form the basis from which the computational algorithm can be constructed. Elements of the supporting test programme will utilise the newly developed Stabilised Hoek Cell and this will be extended to a high pressure testing technique. Plate impact techniques will be developed to directly determine the equation of state of geologic materials and investigate the failure mechanisms (such as failure waves). A dynamic triaxial test rig will be developed in order to investigate the high strain rate behaviour of concrete. The new geologic material models will be validated against precision instrumented trials, covering a range of warhead mechanisms.