Experimental study on the protective performance of a new brittle component subjected to ground shock
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摘要: 为对地冲击作用下地下结构进行有效防护，提出一种泡沫混凝土材质的新型防护构件。与使用实心泡沫混凝土层的防护机理不同，本文中提出的构件在地冲击作用下，首先发生脆断破坏，然后破碎块体间搭接折断、挤压密实。通过构造设计，截断地冲击荷载，减弱荷载传递，改变被保护结构上的荷载形式。通过场地爆炸实验对比了不同防护措施下（无防护、实心泡沫混凝土层防护及新型构件防护）被保护结构的动力响应。实验结果表明：新型构件防护通过脆断、破碎块体的搭接、挤压密实表现出较实心泡沫混凝土层防护更好的防护效果；新型构件防护由于脆断特性，在较小荷载下即可显著削弱荷载传递，避免了实心泡沫混凝土层防护中负效果的出现；地冲击荷载较强时，构件防护层趋于压实，其防护效果逐渐接近实心泡沫混凝土层。Abstract: To effectively protect the underground structures subjected to ground shock, a new protective component made of foam concrete was proposed. Different from the mechanism of the solid foam concrete layer protection, under the action of ground shock, the proposed components firstly exhibited brittlely fracture, and the fractured parts underwent recontact and compaction, in which the ground shock truncation, load transferred reduction and load form modification on the structures were achieved with the response of the designed components. A field experiment was conducted and the comparison of the dynamic response of the structure (with different protection scenarios, i.e. without protection, with a solid foam concrete layer protection and with the proposed component layer protection) suggested that the superior protective performance was achieved with the fracture, recontact, compaction of the new component. Due to the brittle fracture, the load transfer could be significantly reduced under a relatively low ground shock level, with which the negative protection effect using solid foam concrete layer could be avoided. Subjected to a relatively strong ground shock, the proposed component layer tended to compaction, and its protection effect gradually approached that with the solid foam concrete layer.
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Key words:
- foam concrete /
- ground shock /
- underground structure /
- brittle fracture /
- load transfer
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图 2 新型构件的准静态力-位移曲线
Figure 2. Force-displacement curve of a new protective component under quasi-static compression
图 3 脆断后新型构件与传统泡沫混凝土层的力-位移曲线对比
Figure 3. Comparison of force-displacement curves between a fractured new protective component anda foam concrete layer under quasi-static compression
图 4 密度为450 kg/m3的泡沫混凝土的应力-应变关系
Figure 4. Stress-strain curve of the foam concrete with the density of 450 kg/m3
图 18 工况3中实验后新型构件层形态
Figure 18. The protective component layer after explosion in case 3
图 19 工况2中实验后新型构件层形态
Figure 19. The protective component layer after explosion in case 2
表 1 钢的性质
Table 1. Properties of steel
钢材 密度/(kg·m−3) 杨氏模量/GPa 屈服强度/MPa 抗拉强度/MPa 伸长率/% Q235B 7 830 210 235 375 21 
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表 2 爆炸工况
Table 2. Explosion cases
编号 装药质量/g 爆距/mm 埋深/mm 细砂密度/(kg·m−3) 细砂波阻抗/(kg·m−2·s−1) 衰减系数 1 100 500 500 1 450 1.3×105 3.25 2 200 500 500 1 800 5.4×105 3.25 3 200 350 450 1 800 5.4×105 3.25
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表 3 工况2中不同防护手段下加速度峰值的比较
Table 3. Peak accelerations under protecitve methodsin case 2
防护情况 加速度峰值/(m·s−2) 增量比/% 无防护 3 953 0 泡沫混凝土层防护 2 506 −36.6 新型脆断构件防护 1 671 −57.7
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