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https://hdl.handle.net/11681/21644| Title: | Ground shock calculation parameter study. Report 2, Effects of various bottom boundary conditions |
| Authors: | Baladi, George Y. |
| Keywords: | Mathematical models Shock waves Soils--Plastic properties Blast effect Soil mechanics |
| Publisher: | Soils and Pavements Laboratory (U.S.) |
| Series/Report no.: | Technical Report;S-71-4, Report 2 |
| Abstract: | Abstract: A parametric study of the effects of rigid, roller, and transmitting bottom boundary conditions on high-explosive airblast-induced superseismic ground shock calculations was conducted using a U. S. Army Engineer Waterways Experiment Station-modified version of the two-dimensional (2D) axisymmetric LAYER code developed by the firm of Paul Weidlinger, Consulting Engineer. The constitutive relation used was a nonlinear, elastic-plastic, hybrid-type model. The constitutive properties used were those of the two-layered soil profile employed in Report 1 of this series. Seven different calculations were performed to study the effects of the depth to the bottom boundary and the differences in ground shock resulting from the use of different types of boundaries at a given depth. Results of this study showed that the transmitting boundary provides an adequate simulation of an elastic medium beyond the calculation domain for a large class of finite difference 2D nuclear ground shock boundary value problems in elastic, inelastic, and layered media under superseismic conditions. Variations in the depth to this boundary within the bottom layer had a very small effect on the results. Use of the transmitting boundary at a shallow depth resulted in a major reduction in computer requirements and calculation cost. The study also showed that both the roller and the rigid bottom boundaries result in significant spallation phenomena and that calculation results using these two boundaries located at shallow depths provide upper and lower bounds to the radial motions calculated using a shallow transmitting boundary or a very deep bottom boundary (i.e. semi-infinite simulation). Two rigid bottom boundary prescriptions (Rigid Bottoms I and II) were investigated. It was shown that there are two differences between the Rigid Bottom I and II calculations : (A.) a difference in depth of a half box, and (B.) an actual difference in the numerical treatment of the same physical condition. However, Rigid Bottom II, which was coded by using an antisymmetry condition, satisfied all the theoretical requirements. Therefore, it should be used in future rigid bottom calculations. |
| URI: | http://hdl.handle.net/11681/21644 |
| Appears in Collections: | Technical Report |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| TR S-71-4 Report 2.pdf | 8.07 MB | Adobe PDF |  View/Open |