PROPAGATION AND ATTENUATION OF GROUND SHOCK IN DRY SOILS

Abstract

A finite element code CRISDYN has been developed and used to study the propagation and attenuation of stress waves arising from shock and blast loadings in dry soils. In order to ensure that the soil behaviour under ground shock is correctly prescribed, due consideration is given to the proper selection of an appropriate soil model The suitability of the Cam-clay modeL which incorporates a hardening cap and the critical state line, for studying the response of dry soils subjected to high-pressure dynamic loadings is first discussed. A comparison between this model and the more commonly used Sandler cap model is also made. The Cam-clay model is felt to have some slight advantage over the latter in terms of its description of the unloading and recompression behaviour, its ability to model the peak as distinct from the ultimate strength of an overconsolidated material and the economy of soil parameters. Hence, only the Cam-clay model is critically evaluated in this study, although both models were eventually incorporated into CRISDYN. Next, the formulation of the numerical code for the solution of dynamic problems is presented. Some of the important considerations discussed in this section include the choice of a suitable time-integration scheme, enuation solver and transmitting boundaries.