Effects of Loose Sand and Dense Sand on the Response of Underground Empty Pipes due to Accidental Explosions by Simulation
Akinola Johnson Olarewaju
Civil Engineering Department, School of Engineering,
Federal Polytechnic Ilaro, P.M.B. 50, ILARO, Ogun State, NIGERIA
In this study, effects of loose sand and dense sand on the response of underground pipes due to surface and underground accidental explosions was studied. Steel and concrete pipes buried in loose sand and dense sand at various depths below the ground surface was modelled. The material properties for ground media (i. e. loose sand, dense sand and intervening medium), steel and concrete pipes as revealed by several researchers and pipe manufacturers were used. Explosion load parameters were determined using Unified Facilities Criteria (2008). Pipe and soil materials were limited to linear, elastic, homogeneous and isotropic. Equation of motion was solved using time integration technique in ABAQUS/Explicit, a finite element based numerical code. Displacement, pressure, stress and strain were observed at the crown, invert and spring-line of underground pipes and dimensional analysis was used to evaluate the results. From the results, depth plays a prominent role in the response of underground pipes due to accidental explosions. The ratio of deflection of pipes at the crown, invert and spring-line buried in loose sand to that of dense sand at H/D ratios of 1 and 5 is 1 : 1.8 : 2.75 : 2.5 and 1 : 44 : 8 : 18 for surface accidental explosion and at H/D ratios of 1 and 5 is 1 : 2.74 for underground accidental explosion respectively. Mitigation measures to reduce the impact of accidental explosions on underground pipes were suggested.
Keywords: Explosion; Underground; Surface; Pipes; Response; Loose Sand; Dense Sand
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