Distribution Law And Simplified Computation Of Overpressure On Walls Due To Explosion Inside The Closed Space

An accidental explosion taking place in the confined populous building canseriously threaten the people's lives and property, bringing inestimable evilconsequence. As the key of research and design of structure anti-explosion, the studyfor the overpressure model on walls inside the closed space is increasingly causing theattention of the domestic and foreign scholars and has become one of the mostimportant parts in the field of the basic research of anti-explosion engineering.Based on the theory of explosion mechanics and using the ALE method of theLS-DYNA software, the paper makes a numerical analysis for the distribution law ofoverpressure on walls induced by an explosion inside the closed spaces such as acuboid and an infinite tunnel, and presents a simplified method for the calculating ofoverpressure histories on walls. The primary works include the following two parts.First, the LS-DYNA software is used to establish the models for a cube spacewith the side length of 2m and an infinite square-section tunnel with the side length of2m. An explosive of the reference charge, 0.205kg 0 W ? , is set at each node of theirinner spaces, and the data of the peak values and durations of overpressure on wallsdue to its explosion are collected together and shown in a manner of the envelopediagram using the origin graph software. Then, the distribution laws of the inducedoverpressure on walls of these two kinds of closed spaces are analyzed qualitatively.Second, the data of overpressure histories at all nodes of the walls induced by anexplosion of the reference charge weight, 0.205kg 0 W ? , at each node inside the twoclosed spaces, including the cube with the side length of 2m and the square-sectiontunnel with the side length of 2m, are collected together to form the two referencedatabase called DEPCW and DEPTW, respectively. Afterwards, based on the thoughtof iso-parametric finite element, an interpolating algorithm of overpressure history atan optional point on walls due to an explosion of the reference charge at an optionalposition inside above two spaces is proposed. Besides, some ratio coefficients of thepeak value, arriving time and duration of overpressure on all walls, reflecting thechanges of the charge weight and space size, are derived along with their contributivefactors to the overpressure history of the calculated point on the wall, and thenintroduced into the above interpolating algorithm for some appropriate modifications, which finally gives an approximate simulation about the overpressure history on wallscaused by an explosion of optional charge weight inside a cuboid space or arectangle-section tunnel with the optional size.From above works, some main conclusions are drawn as follows:The distribution law of overpressure on walls due to an explosion in the closedspace is very complicated, and is difficult to be expressed by a unified mathematicalformula. Generally speaking, the peak value of overpressure on walls reduces with theincrease of the scaled distance between the overpressure-calculated point and theexplosion source, while its arriving time increases with the increase of that distance.The peak value of overpressure at the corners of the space, however, sharply increasesbecause of the intensive reflection effect of blast waves there. In addition, by meansof the proposed interpolating algorithms and corresponding reference databases, theoverpressure history on walls induced by an explosion inside the cuboid space and therectangle-section tunnel not only can be calculated without any limit to the explosiveposition, charge weight, overpressure-calculated point position and space size, butalso has a good agreement with the result of using LS-DYNA software. This fullyshows the rationality and accuracy of this proposed method. Furthermore, for thesame computer configuration, when compared with the LS-DYNA software method,the proposed method in this paper can make a great deal of calculating time saved andtherefore the calculating efficiency increased a few decade times or even a fewhundred times. Consequently, this will have a good prospect in engineeringapplication.