新型护栏型结构防爆墙研究

Blast wall is commonly constructed for people and important structure protection against blast loads. Current practice in designing the blast walls is based primarily on traditional concept of structural strength and ductility to resist the expected blast loads. Depending on the required protection level, usually these designs lead to huge structures which are not only rather expensive but also often not suitable for construction in urban areas. With the development of new structural forms and new materials, recently more research efforts are devoted to developing sandwiched blast walls or blast walls with sacrificial layers. These new designs lead to relatively lightweight but usually large dimension walls. Besides they are quite expensive, the primary drawback of the new designs is that they depend on large plastic deformation of sandwiched or sacrificial layers to absorb blast energy for structure protection. Plastic deformation reduces their capacity in resisting blast loading. Therefore they are not suitable to resist repeated blasting attacks. This project will explore the possibility of developing a completely new blast wall designs based on the concept of wave interference. Instead of using solid walls to resist the blast loadings, the new design uses fence type structural columns placed at strategic locations as wave stoppers to generate wave reflection, refraction and interference between the reflected and refracted waves from different columns to cancel out wave energy. This new design concept has been used in optic and acoustic area to dissipate light energy and noises, but not in blasting engineering to dissipate blast wave energy. This innovative blast fence wall design is expected to lead to significant savings in constructing the blast walls, increase the blast wall protection levels for people and structures behind the wall, and also very likely to have wide applications in other types of blast resistant structures.

目前防爆墙的设计主要是通过结构强度和延性的传统设计理念来抵御爆炸荷载。实体防爆墙一般都体积庞大，这不但增加建造成本，也不适合在城市地区应用。随着新型材料的发展，越来越多的学者研究开发夹层防爆墙来抵抗爆炸荷载。夹层防爆墙通过夹层的大变形来吸收爆炸能量以达到保护结构的目的，一旦夹层塑性变形后，其抵抗爆炸荷载的能力大幅下降，因此不适合于抵御重复爆炸荷载。本项目摒弃传统实体防爆墙抵御爆炸荷载的理念，将基于波的传播和干涉理论开发一种新的防爆墙设计。新的设计通过在重要防爆区域放置护栏型结构柱，引起产生于相邻柱的反射波和折射波的再反射、折射和相互作用，进而消减部分波能。这一设计理念已经用在光学和声学领域来消除光能和噪音，但还没有被用于爆炸工程领域以消除爆炸波的能量。这一创新设计在增加防爆墙对墙后人员和结构的防护等级的同时，可以极大的节省材料和建造成本。该设计理念也有望在其他类型的防护结构中得到应用。

传统的防爆墙往往为砌体墙、混凝土墙或钢混组合墙等实体形式。一方面此类防爆墙在近距离爆炸荷载下会产生大量碎片以相当高的速度向后方飞散冲击，对墙后建筑、设施和人员等形成极大安全威胁；另一方面，在城市范围内的关键建筑周围放置此类实体防爆墙，往往会造成民众的恐慌情绪，对社会秩序带来严重负面效应，对社会经济的影响可能超过爆炸事件本身。本项目基于波的传播和干涉理论开发一种新的防爆墙设计，通过在重要防爆区域放置护栏型结构柱，引起产生于相邻柱的反射波和衍射波的再反射、干涉等作用，进而消减部分波能。本项目的主要研究内容为（1）基于爆炸波传播的理论推导，应用AUTODYN有限元分析软件通过二维数值模拟进一步理解爆炸波传播的规律。然后在二维数值模拟中针对不同配置的护栏柱分析其减弱爆炸荷载的有效性；（2）根据二维数值模拟的研究结果，通过设计现场缩尺爆炸试验，对新型护栏型防爆墙的排布进行研究，进一步验证不同排布的护栏型防爆墙对爆炸荷载的防护有效性；（3）基于二维数值模拟及现场试验的研究结论，对护栏型防爆墙进行三维数值模拟拓展研究，对其在近距离爆炸荷载作用下的结构响应及具体排布参数进行了详细分析，最终提出护栏型防爆墙的排布建议。基于最优排布的护栏型防爆墙，通过大量数值模拟计算，分析数据最终得到护栏型防爆墙后作用在建筑物表面的反射压力和冲量。这一全新设计理念在增加防爆墙对墙后人员和结构的防护等级的同时，可以避免产生碎片灾害，极大的节省材料和建造成本，同时适用于城市环境结构减爆，在军民两用领域有着极大的应用前景。