爆炸荷载下刚-柔耦合围岩支护结构二维平板动态损伤破坏特征试验研究

Dynamic damage characteristics of two-dimensional flat plate of rigid-flexible coupling surrounding rock supporting structure under blast loading

为探究爆炸冲击荷载下以橡胶水泥砂浆(RCM)作为柔性吸能材料的“刚-柔耦合”围岩支护结构的动态稳定性,通过搭建二维平板爆炸冲击试验系统,开展单体平板试件在中心起爆方式下和组合体平板试件在偏心起爆方式下的单孔爆炸冲击荷载试验;并从炮孔动态膨胀响应特征、剥落区形成机理和爆生裂缝扩展机理3个方面,探究“刚-柔耦合”围岩支护结构二维平板试件的动态损伤破坏特征。最后,从应力波传播和协调变形2个方面分析讨论“刚-柔耦合”围岩支护结构中多层材料间的耦合作用特征与围岩稳定性机理,进一步印证以RCM作为柔性材料的“刚-柔耦合”围岩支护结构降低围岩及其支护结构动力损伤的潜力。研究结果表明:随橡胶体积分数增大,平板试件整体的损伤破坏程度明显减小;尽管RCM单体平板试件的爆后炮孔直径和剥落区面积因橡胶体积分数的增大而有所增大,但RCM有效降低了组合体平板试件的爆后炮孔直径、剥落区面积和爆生裂缝总长度。平板试件在爆炸冲击荷载作用下主要受到爆炸冲击波与爆轰气体的共同作用,尤其在底板对炮孔的封闭约束下,炮孔中也因爆炸能量的瞬间释放形成了向上的聚能射流效应,进一步导致了V形爆坑剥落区的形成。在同一起爆方向下,当橡胶体积分数为60%时,R-R-H和H-R-R的裂缝长度总和最小;在同一橡胶体积分数下,相比于H-R-R,R-R-H的裂缝长度总和最大降低了46.25%。

To explore the dynamic stability of"rigid-flexible coupling"surrounding rock supporting structure with rubber cement mortar(RCM)as flexible energy-absorbing material under blasting impact load,the single-hole blasting impact load tests of single flat plate specimens in central initiation blasting and combined flat plate specimens in eccentric initiation blasting were carried out by building a two-dimensional flat plate blasting impact test system.The dynamic damage and failure characteristics of two-dimensional flat plate specimens with"rigid-flexible coupling"surrounding rock supporting structure were explored from three aspects,i.e.,the dynamic expansion response characteristics of blasthole,the formation mechanism of exfoliation zone,and the propagation mechanism of explosive cracks.Finally,the coupling characteristics of multi-layer materials and the stability mechanism of surrounding rock in"rigid-flexible coupling"surrounding rock supporting structure wre analyzed and discussed from stress wave propagation and coordinated deformation,which can further confirm that the"rigid-flexible coupling"surrounding rock supporting structure with RCM as flexible material has the potential to significantly reduce the dynamic damage of surrounding rock and its supporting structure.The results show that the damage degree of the flat plate specimen decreases obviously with the increase of rubber volume fraction.Although the blasthole diameter after blasting and exfoliation zone area of RCM flat plate specimen increase with the increase of rubber volume fraction,RCM effectively reduces the blasthole diameter after blasting,exfoliation zone area,and total length of explosive cracks of combined flat plate specimen.Under the explosion impact load,the flat plate specimen is mainly subjected to the combined action of explosion shock wave and detonation gas,especially with the sealing constraint of the bottom plate to the blasthole,the upward jet flow effect is formed due to the instantaneous release of explosion energy in the blasthole,which further leads to the formation of V-shaped blasting crater exfoliation zone.In the same blasting direction,when the rubber volume fraction is 60%,the total crack length of R-R-H and H-R-R is the minimum.At the same rubber volume fraction,compared with H-R-R,the total crack length of R-R-H decrease by 46.25%at most.