冲击作用下混凝土板-缓冲层组合结构动力响应

钢筋混凝土板-缓冲层组合结构常用于落石灾害防治。为研究此类结构在落石冲击作用下的动态响应，基于ABAQUS有限元，以缓冲层厚度、落石冲击速度为参变量，开展了冲击力、缓冲效果、钢筋混凝土板损伤的数值模型研究。结果表明：冲击过程中，落石与缓冲层表面的名义冲击力远大于缓冲层与混凝土表面的真实冲击力，在缓冲层为0.6 m，冲击速度分别为20，15，10 m/s时，冲击力衰减率分别为42.0%，42.0%，40.0%；与目前典型冲击力计算模型对比分析发现，在不同冲击速度下，冲击力与冲击速度呈正相关。研究结果与日本公式及隧道手册计算公式的基本一致。对混凝土板位移分析表明：在一定的缓冲层厚度下，随冲击速度的增大，永久变形增大，回弹量占总变形比例较小；最大损伤范围与缓冲层厚度关系不明显。在缓冲层厚度相同的情况下，冲击中心对应的板面与损伤外边缘连线形成的损伤锥锥角介于30°~ 45°。冲击速度很大程度上影响损伤程度和损伤范围。研究结论对落石防护结构的合理设计具有重要指导意义。

Dynamic response of reinforced concrete slab-buffer composite structure under impacts

The reinforced concrete slab-buffer layer combination structure is often used for the prevention and control of rockfall disasters. In order to study the dynamic response of such structures under the action of falling rocks, based on ABAQUS finite element method, the impact force model, buffer effect and reinforced concrete slab damage were studied numerically with buffer layer thickness and falling rock impact velocity as parameters. The results show that during the impact process, the nominal impact force between the rockfall and buffer layer surface is much larger than the real impact force. When the buffer layer is 0.6m and the impact velocity are 20m/s, 15m/s, 10m/s respectively, the impact attenuation rates are 42.0%, 42.0%, and 40.0%. Compared with the current typical impact calculation model, it found that the impact force was positively correlated with the impact velocity at different impact speeds, which was in agreement with the Japanese formula and the tunnel specification. The displacement analysis of the concrete slab showed that under a certain buffer layer thickness, as the impact velocity increased, the permanent deformation increased, and the rebound amount accounted for a small proportion of the total deformation; the maximum damage range had no relation with thickness of the buffer layer. In the case of same thickness of the buffer layers, the damage cone angle formed by the corresponding plate damaged position and the outer edge of the damage was between 30° and 45°. The impact velocity largely affected the extent of damage and the extent of damage. The conclusions of this paper have important guiding significance for the design of rockfall protection structure.