滚石冲击闭孔泡沫铝夹芯板耗能缓冲机理研究

Study on the Dissipating Effects of Aluminum Foam Sandwich Panel Under Rockfall Impact

在山区构筑物外表面覆盖一层缓冲材料能有效减小滚石冲击危害,达到保护工程结构的目的。为此,将泡沫铝作为一种耗能缓冲材料引入滚石灾害冲击领域,并将其与钢板组合为夹芯板结构,采用静力压载试验及动力有限元对滚石冲击泡沫铝夹芯板动力响应进行分析,揭示泡沫铝夹芯板耗能缓冲作用机理。结果表明:泡沫铝及夹芯结构在进入屈服强度后有较宽的耗能缓冲平台,可吸收大量冲击能量;同时夹芯板结构可有效降低被保护物结构挠度变形,伴随夹芯钢板厚度不断增大,垫层冲击坑深度不断降低,被保护结构中心点变形有较明显下降,但过大的钢板厚度使得泡沫铝夹芯板整体刚度增强,反而不利于泡沫铝夹芯板能量耗散。因此,在泡沫铝缓冲垫层结构设计时,应综合考虑被保护物结构所容许的变形量及承受冲击力双重控制指标。

A cushion layer can efficiently protect the structures in mountainous areas from impact damages of rockfall hazard. The aluminium foam,as a kind of energy dissipation cushion material,was introduced into rockfall disaster mitigation areas. This type of cushion was composed of aluminium foam with embedded steel plate that was made to be a sandwich board structure. Dynamic response of rockfall impacting the aluminum foam sandwich panels was analyzed by static experiment and dynamic finite element method,revealing the energy dissipation buffer mechanism of aluminium foam sandwich board. The results showed the existence of a wide energy buffer platform in the stress yield stage,which could absorb lots of energy so as to achieve the purposes of energy dissipating. The sandwich board structure could effectively reduce the deflection deformation of the structures. When the embedded steel plate thickness increases,the cushion impact pit depth decreases and the deformation of protected structure center also decreases remarkably. However,too thick steel plate will increase the overall rigidity of the sandwich panel,and reduce the energy dissipation of the panel. Therefore,the double indexes of deformation and impact force under rockfall impact structure should be comprehensively considered when the structure of aluminum foam sandwich board is designed.