超高性能混凝土临空板接触爆炸破坏效应实验研究

Experimental study on local damage effect of ultra-high performance concrete slabs under contact explosion

为了研究超高性能混凝土(ultra-high performance concrete,UHPC)的抗接触爆炸性能,开展了C120、C150和C180等3种强度等级共24块UHPC临空板的接触爆炸实验,定量分析了不同药量时典型配筋与不配筋靶板的局部破坏特征,得到了UHPC的爆炸临界震塌系数、压缩系数和成坑系数。结果表明:相同药量下,UHPC板的正面破坏程度随材料强度的提升而减轻;强度越高,爆炸成坑系数和压缩系数越小,抗爆性能越好;配筋率较低时,钢筋对UHPC板正面爆坑尺寸及背面震塌破坏程度影响较小,但对板的整体变形起到了一定的减轻作用,能够减小板底的剩余挠度和裂缝宽度;C150靶板的爆炸临界震塌系数最小,不大于0.251 m/kg^(1/3),C120和C180靶板的爆炸临界震塌系数相近,不大于0.285 m/kg1/3。在设计、使用纤维含量较高的大尺寸UHPC构件时,应特别关注由纤维分布方向性引起的材料各向异性和结构力学性能的变化。

In order to study the contact explosion resistance of ultra-high performance concrete(UHPC),24 contact explosion experiments were conducted.The target slabs were cast in UHPC with or without reinforcement,and the compressive strength grades of the UHPCs were C120,C150 and C180.The slabs were laid on supporting ring beams and the back faces of the slabs were free.The TNT was placed on the center of the front face.The size of the target slab was 1.5 m×1.5 m×0.3 m,and the main reinforcements were φ12 HRB400 with 200 mm×200 mm grid distance.Based on the experiments,the local failure characteristics of typical reinforced and unreinforced target slabs under the shock of different explosive weights were quantitatively analyzed,and the critical collapse coefficient,compression coefficient and explosion crater coefficient of the UHPC slabs were obtained.The results show that,at the same explosive weight,the damage degree of the UHPC slabs decreases with the compressive strength.The higher the compressive strength,the smaller the compression coefficient and the explosion crater coefficient.When the reinforcement ratio is low,it has little effect on the front crater size and the back collapse damage degree of the UHPC slab,but has a certain role in reducing the residual deflection and crack width at the bottom of the slab.For the UHPCs in this paper,the critical collapse coefficient of the C150 slap is the smallest,no more than 0.251 m/kg1/3;and the C120 slap and C180 slap are similar,no more than 0.285 m/kg^(1/3).The critical collapse coefficients of the C180 UHPC is not the smallest because there are more steel fibers in the horizontal direction than in the vertical direction.When designing or using large size UHPC structures with high fiber content,special attention should be paid to the material anisotropy and the changes in structural mechanical properties due to the directivity of the fiber distribution.