Seismoacoustic wave generation for two consecutive surface chemical explosions of the same yield (approximately 1 ton TNT-equivalent) was studied during the Large Surface Explosion Coupling Experiment (LSECE) conducted at Yucca Flat on the Nevada National Security Site (NNSS) site in alluvium geology. We have performed numerical simulations for both chemical explosions to investigate how the non-central source initiation, site topography and soil mechanical properties affect the evolution of the explosion (fireball and cloud), its crater, and variations in the generated blast waves. The results can be used to improve the understanding of surface explosions and their effects and how those effects can be used to infer source information such as explosive yield and emplacement. We find that the non-central detonation of the explosive cube results in non-axisymmetric blast overpressures which persist through the strong and weak shock regimes, in this case out to 200 m and more. The pattern of the secondary shock (i.e., shock created due to slowing explosive products within the expanding fireball) is also affected and its arrival relative to the main shock and may be indicative of explosive type due to its dependence on the explosive products ratio of heats. Small reflections are visible within the overpressure signal that are most probably due to small artifacts in blast path. Importantly, the fireball growth, cavity generation, and cloud formation also depart from spherical and ideal approximations due to ground interactions and material dependence, which shows the importance of realistic geomaterial models for accurate prediction. The asymmetry in peak overpressure is diminished for the second chemical explosion, which was placed in the crater of the first. Numerical modeling shows that the explosive jetting created by the non-central detonation is reduced upon interaction with the crater walls and this has the effect of making the blast generation more axisymmetric.

In the modern world, the demand for bunkers has grown significantly as a vital means of protection against blast loads. This study investigates the structural response of underground bunkers subjected to surface blast loads using finite element (FE) analysis in ABAQUS/Explicit. The model uses the Mohr-Coulomb model for soil, Concrete Damage Plasticity (CDP) for the bunker liner, and Johnson-Cook for steel and aluminum. Five dome curvatures (flat, D/8, D/4, 3D/8, and D/2) were analyzed under a 1000 kg TNT explosion. Results show higher stress, deformation, and tension damage with increasing curvature, especially for D/2. Organic sandy clay caused maximum stress and deformation. Two mitigation strategies were proposed: upgrading concrete from M40 to M50 and adding an aluminum 2024-T3 liner. M50 concrete reduced stress by 19.23%, deformation by 5.09%, and damage by 2.63%, while the aluminum liner provided greater protection, reducing stress by 83.12%, deformation by 58.03%, and damage by 67.07%.

Failure of important supporting structural systems such as pipelines carrying water from the faraway source may be disastrous to the site environment and lead to public clamor. Such events resulting from blasts (intentional/unintentional) do not give any warning of impending failure as their duration is very short and intensity is very high as compared to other loadings excited by the earthquake. Therefore, the investigations for the response of buried pipelines under explosive loading are of considerable interest. This study is executed for numerical analyses using an advanced coupled Eulerian-Lagrangian finite-element (CEL-FE) approach to predict the anti-blast performance of a buried steel pipeline loaded by on- and below-ground blast loading. A 3D numerical model of the buried pipeline is first created in the ABAQUS software and analyses are performed with ABAQUS built-in explicit module to investigate the role of carried liquid (e.g., water) on the anti-blast response of the pipeline. The considered pipeline is seamless and has an outer diameter of 1e+03 mm, a wall thickness of 1e+01 mm, and a total length of 12000 mm; typical dimensions for water, gas, and oil transmission pipelines. It is buried in a brown clayey soil medium at a depth of 2000 mm (= 2 x pipe diameter) below ground level. Simplified Johnson-Cook plasticity (JCP), Jones-Wilkins-Lee (JWL)-Equation-of-State (EOS), ideal gas EOS, Us Up Hugoniot EOS, and Mohr-Coulomb plasticity (MCP) constitutive models, respectively, are considered to define material properties for the pipeline, TNT, air, water, and soil medium. Responses are compared and discussed. Significant improvement in the blast performance of the pipeline carrying 50% water has been observed in terms of dynamic response and damage compared to the empty pipeline showing that the water proactively contributes to protecting the pipeline from getting severely damaged by the blastwaves.