地下拱形结构侧顶爆炸的破坏模式及影响因素

Failure Mode and Influencing Factors of Underground Arched Structure Subjected to Side Top Blast

钢筋混凝土拱形结构作为地下防护工程的主要形式,其在近区爆炸荷载作用下的动态响应和破坏模式对防护工程设计具有重要的指导意义。为探讨地下拱形结构在45°侧顶爆炸作用下的破坏模式及影响因素,对侧顶爆炸作用下的钢筋混凝土直墙圆拱形结构开展试验和数值模拟研究。试验加载方式,在地下围岩梯恩梯装药距离拱形结构0.5 m处进行方式;基于有限元分析软件LS-DYNA,采用流体与固体耦合算法,建立围岩、混凝土和钢筋三维分离式实体模型,对钢筋混凝土拱形结构的动态响应过程进行数值模拟,模拟得到的拱形结构破坏现象与试验结果吻合较好。分析了不同装药量下结构的破坏模式以及不同混凝土强度、拱形结构截面厚度和结构跨度对拱动态响应的影响。结果表明:随着装药量增加,结构的破坏模式由层裂破坏、弯曲破坏逐渐过渡到剪切破坏和整体破坏;提高混凝土强度和拱截面厚度能显著改善其抗爆性能,跨度的增加会使结构背爆面损伤程度降低。

Reinforced concrete arched structure is the main structure of underground protection engineering,and its dynamic response and failure mode under the action of explosive load in the near area have important guiding significance to the design of protection engineering.A circular arched structure with reinforced concrete straight walls was tested and numerically simulated to explore the damage effect of underground arched structure under the condition of 45°side top blast.In the test,TNT was loaded in the underground surrounding rock at a distance of 0.5 m from the arched structure.A three-dimensional separated solid model of surrounding rock,concrete and steel bars was established with finite element analysis software LS-DYNA.In the numerical simulation,a fluid-solid coupling algorithm is used to simulate the dynamic response process of the reinforced concrete arched structure.The simulated failure phenomenon of the arched structure is in good agreement with the tested one.The failure mode of the structure under different charge masses and the influences of concrete strength,section thickness and span of arched structure on the arch dynamic response were analyzed.The results show that the failure mode of the structure gradually transitions from spalling failure and bending failure to shear failure and overall failure with the increase in the charge mass.Increasing the strength of concrete and the thickness of arch section can significantly improve its blast resistance,and the damage to the back explosion surface of the structure can be reduced with the increase in span.