In view of the difficulty in implementing active reinforcement for the high-level rockfall disaster occurred in the high-steep slope zone of the"5·12"Wenchuan earthquake area in 2008, the pile-plate retaining wall is a passive protection measure used in the proposed interception site, and its applicable terrain slope is 25°～35°.In order to study the dynamic response of such a pile-plate structure under rockfall impact load, numerical simulation is carried out by coupling finite element and infinite element.Combined with the classical elastoplastic theory, the characteristic parameters such as impact force, penetration depth and structural energy dissipation effect of the pileplate retaining wall during loading and unloading rebound process under different impact conditions are systematically analyzed, and the impact resistance of the structure is clarified.The results show that the"infinite element"boundary can effectively reduce the error caused by the reflection of the stress wave at the artificial truncation boundary.In the case of impact speeds of 10 m·s-1, 15 m·s-1and 20 m·s-1, 25 m·s-1, the calculated impact forces are 1.9MN, 2.5MN, 3.1MN, 3.7MN, respectively.The results are consistent with the Kawahara model, but larger than the Labiouse model and the Hertz elastic solution.According to the concrete damage theory, the classification of damage level is proposed and the degree of structural damage is effectively quantified.When the impact speed is greater than 20 m·s-1, the pile and plate concrete tensile damage is seriously damaged, and the structure has the risk of completely losing the bearing capacity.The calculation methods and results in this paper can provide practical guidance for the related structural design.%桩板拦石墙是针对2008年"5·12"汶川震区高陡斜坡带高位落石灾害难以实施主动加固,而在拟设拦挡部位所采用的一种被动防护措施,适用地形坡度介于25°～35°.为研究此类桩板结构在落石冲击荷载下的动力响应,采用有限元与无限元耦合进行数值模拟,结合经典弹塑性理论,系统分析了桩板拦石墙在不同冲击工况下弹塑性加载与卸荷回弹过程中冲击力、贯入深度、结构耗能效果等特征参量,明确了结构的抗冲击特性.结果表明,本文采用的"无限元"边界可以有效地减小应力波在人工截断边界处反射造成的误差.在冲击速度为10 m·s-1、15 m·s-1、20 m·s-1、25 m·s-1的情况下,本文计算冲击力的大小分别为1.9 MN、2.5 MN、3.1 MN、3.7 MN,结果与Kawahara模型一致,但较Labiouse模型和Hertz弹性解大.根据混凝土损伤理论,提出了损伤等级分类,有效地量化结构破损程度.当速度大于20 m·s-1时,桩、板混凝土拉压损伤严重,结构存在丧失承载力的风险.本文的计算方法与结果可为相关结构设计提供实际指导.
展开▼
