抗落石冲击被动柔性防护网的设计选型

Design Selection of Passive Flexible Rockfall Barrier for Resisting Rockfall Impact

以残余拦截高度和落石缓冲距离作为评价被动柔性防护结构变形性能的关键技术指标,在此基础上提出了一种用于拦截和缓冲落石冲击能量的新型被动柔性防护网。利用ANSYS/LS-DYNA大型通用有限元分析计算软件建立了3种形式的环形网模型,从最大耗能、残余拦截高度和落石缓冲距离3个方面对环形网的耗能性能和变形性能进行了分析。结果表明:带竖向支撑的环形网可以有效降低落石的缓冲距离并提高环形网的残余拦截高度,但环形网的最大耗能均有不同程度的下降;与无支撑和双支撑环形网相比,单支撑环形网具有以下优点:最大耗能占比较高,在瞬时冲击荷载作用下具有迅速衰减落石冲击能量的功能,落石的缓冲距离小且防护性能基本不受落石冲击位置的影响。在防护网铺设位置距离道路较近的边坡、陡峭边坡中的防护网水平铺设以及二次防护等落石防护工程中,优先选用单支撑环形网。

Taking residual interception height and falling rock buffer distance as the key technical indexes to evaluate the deformation performance of passive flexible protective structures, a new passive flexible rockfall barrier for intercepting and buffering the impact energy of falling rocks is proposed. Based on ANSYS/LS-DYNA,general finite element analysis and calculation software, three types of ring net models are established, and the energy consumption and deformation performance of ring net are analyzed from three aspects: maximum energy consumption, residual interception height and falling rock buffer distance. The results show that the ring net with vertical support can effectively reduce the buffer distance of falling rocks and increase the residual interception height of the ring net, but the maximum energy consumption of the ring net has decreased to some extent. Compared with unsupported and double-supported ring nets, single-supported ring nets have the following advantages: the maximum energy consumption ratio is relatively high, it has the function of rapidly attenuating the impact energy of falling rocks under the action of instantaneous impact load, the buffer distance of falling rocks is small, and the protective performance is basically not affected by the impact position of falling rocks. Therefore,the single-supported ring net should be preferentially used in rockfall protection projects such as the slope with the rockfall barrier laying position close to the road, the horizontal laying of rockfall barrier in the steep slope and the secondary protection.