侧向点爆炸作用下浅埋圆拱结构塑性破坏规律

Evolution Rule of Plastic Zone on Shallow Buried Arch Structures Subjected to Side Blast Loads

摘要:

考虑近场侧向爆炸时荷载的非对称性、不均匀性和局部性，利用几何关系推导侧向爆炸时结构表面荷载的解析式.针对不同的结构截面受力模式，利用轴力和弯矩共同作用下的截面塑性破坏准则，并基于四铰破坏机制，提出浅埋圆拱结构塑性破坏简化计算方法.基于Matlab软件，判断圆拱结构塑性破坏时截面的受力模式，并确定结构塑性铰分布.结果表明：在2个拱脚附近、荷载峰值作用处，以及背爆面一侧拱肩位置产生塑性铰；在爆炸偏角较小时，塑性铰先出现于背爆面的拱脚和爆源投影点位置；随着爆炸偏角的增大，第1个塑性铰出现于迎爆面的拱脚位置.在实际工程中，大偏压是较为理想的破坏模式.

Abstract:

Considering the asymmetry, nonuniformity and local characteristics of load in the near field, the expression of lateral load was derived by geometrical relation. According to the different bearing modes of structural section, the plastic failure criterion under the joint action of axial force and bending moment was given. Based on the fourhinge failure mechanism, a simplified calculation method for the plastic damage of shallow buried arch structures was proposed. The bearing mode of circular arch plastic failure was calculated based on Matlab, then the distribution of structure plastic hinge was obtained. It is shown that plastic hinges are produced near two arches, at peak load, and at the shoulder of backside blast surface. When the bias angle is small, the plastic hinge firstly appears at the arch of backside blast surface and the position of projection point of explosion source. As the blast angle increases, the first plastic hinge appears at the arch of front blast surface. In practical engineering, large bias is an ideal failure mode.