• Journal of Ocean Engineering and Technology
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• v.29 no.1
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• pp.70-77
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• 2015

The purpose of this study was to provide fundamental data for an anchor collision simulation of an FCM (flexible concrete mattress). Numerical material models (elastic-perfectly plastic model, Drucker-Prager model, and RHT concrete model) were compared. ANSYS Explicit Dynamics was used for collision analyses. An FE model was used for the anchor, FCM, andreinforcement bars. The results showed that the behavior of the FCM was verydifferent that those ofthe material models. In particular, the effect of the pressure dependent strength was most noticeable among the properties of concrete.

• Explosives and Blasting
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• v.41 no.3
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• pp.13-25
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• 2023

The conventional bench blasting method uses the bottom initiation in all blast holes in a round, whereas the MDS (mixture detonation system) method applies the bottom and top initiations alternately according to the spatial position or temporal sequence of each blast hole. The former and latter are respectively called the SMDS (spatial MDS) and TMDS (temporal MDS) methods. Another variant called MMDS (modified MDS) is designed for the specific use in the site having a fly-rock problem. This study compares the MDS method to the conventional method in the aspect of rock fracturing effect. The comparison is made by numerical simulations for a two-row bench blasting model in the LS-DYNA. The SPH-FEM coupling method is utilized for constructing the blasting model. The SPH elements are used for the rock in the near-field region of the blast holes, and the FEM elements for that in the far-field region. The RHT material model is used for the rock. As a result of the simulations, it was found that up to 0.4 m deeper damaged zone was appeared in the SMDS method than in the conventional method for the case of the burden 1.6 m and bench height 3.0 m. In addition, the fly-rock velocity to the normal direction of the bench slope was appeared about 2.0 m/s lower in the MMDS method compared to the other methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.1-7
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• 2017

In general, the large loads which are applied from explosion, impact, earthquake and wind at a short time caused the materials of structures to large deformations, rotations and strains locally. If such phenomena will be analyzed, hydrocodes which can be considered fluid-structure interaction under computational continuum mechanics are inevitably needed. Also, the explosion mechanism is so complicated, it is reasonable that the behaviors of structure are predicted through explosion analyses and experiment at the same time. But, unfortunately, it is true that explosion experiments are limited to huge cost, large experiment facilities and safety problems. Therefore, in this study, it is shown that the results of explosion analyses using the AUTODYN are agreed with those of existing explosion experiments for reinforced concrete slabs within reasonable error limits. And the explosion damage of the same reinforced concrete slab are assessed for quite different reinforcement arrangement spacings, concrete cover depths, and vertical reinforcements. From the explosion analyses, it is known that the more the ratio of slab thickness to reinforcement arrangement spacing is increased, and small-diameter reinforcements are used than large-diameter reinforcements on the same reinforcement ratio, and vertical reinforcements are used, the more the anti-knock capacities are improved.