Numerical Assessment and Repair Method of Runway Pavement Damage Due to CBU Penetration and Blast Loading

Jaeduk Han,Injae Hwang,Sungil Kim

doi:10.3390/app12062888

Jaeduk Han, Injae Hwang + Show 1 more

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https://doi.org/10.3390/app12062888

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Abstract

This paper addresses the protection capability of a runway pavement by executing a field blast test on an airfield pavement subjected to blast loading from a CBU (cluster bomb unit), and by confirming the numerical simulation of warhead penetration and the form of damage. The CBU’s blast loading applies the BAP 100 of an air-to-ground munition in a similar scale. Penetration depth is calculated by a formula which incorporates the terminal speed of a free-falling cluster munition dispersed 20 km above the ground. According to the result of the calculation, the penetration depth by a cluster munition is 33 cm from the surface of the pavement. The field blast test was conducted based on this result. Furthermore, LS-DYNA software simulation was used to assess the condition of damage, determined by the depth of penetration and explosive pressure from a free-falling CBU landing on the airfield pavement from 20 km above the ground. The condition was ultimately used to verify the result of field testing and to confirm the scale of damage repair. The depth of explosion was 78 cm, from the surface to the crushed stone and sand layer below the pavement, and the diameter was 30 cm. The size of the crushed concrete that needed to be removed was an average diameter of 156 cm. The simulation result confirms that the diameter and depth of the crater are 67.6 cm and 67 cm, respectively, when the CBU is detonated under the same depth as the field testing, and the height of upheaval is 12 cm. The most appropriate method for repair, after a series of reviews, is to cut and remove a concrete slab 1.8 m × 1.8 m and cast the crushed stone layer disrupted from the explosion, followed by repairing the removed damaged concrete slab sections using rapid hardening concrete.

Highlights

The recent history of war verifies the importance of air operations in modern warfare, in which the outcome of a war is determined by the establishment of air superiority in the early phase of war
A cluster bomb unit delivered by a ballistic missile is normally dispersed approximately 20 km above the ground, flies vertically before free falling onto the target
Results and Analysis of Modeling After drilling the concrete pavement surface, explosive PBXN-109 was installed at 33 cm below the pavement surface to simulate the explosion

Summary

Introduction

The recent history of war verifies the importance of air operations in modern warfare, in which the outcome of a war is determined by the establishment of air superiority in the early phase of war. This study assesses the protection capability of the rigid concrete pavement from such attack by confirming the scale of damage from detonating explosives in field with the equivalent level of explosion of a CBU; and verifies the depth of penetration by a warhead and its damage condition, using LS-DYNA software. The study simulated by detonating the equivalent amount of TNT installed under the airfield pavement at the same level of depth, and confirmed the damage condition to the pavement. The test confirmed that an explosion inside the concrete pavement creates a disruption due to its pressure, from the surface of pavement down to 78 cm deep where a sand layer is located; and the concrete slab deforms to approximately 156 cm due to upheaval, breaking, and other factors, consequentially limiting the overall traffic of aircraft and requiring removal of these objects. The appropriate way to repair the pavement was found to be removing the 1.8 m × 1.8 m concrete pavement sections where plastic deformation occurred and applying a high-early-strength concrete method [3,4]

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