开放段长城敌台接闪器的设置

Installation and Setting of Air-Termination System in Great Wall Watchtowers in Sections Open to Tourists

在开放段长城的敌台上设置接闪器,既要考虑其型式和保护范围,还应充分考虑到设置接闪器对敌台墙体的扰动及对长城整体风貌的影响。本文提出了对长城敌台的直击雷保护,宜采用接闪杆和接闪带的组合型式作接闪器。在执行对长城最小干预的文物保护原则基础上,根据长城的防雷类别,运用滚球法保护原理,针对可登临敌台游人的保护,提出了接闪杆应设置在敌台垛墙4个外角处、高度宜控制在4.5m以下,指出采用接闪杆保护游人仍存在一定的局限性;明确了设置在不可登临敌台上接闪杆的高度不宜超过1m。探讨了减少接闪杆数量的可能性,结论为:当接闪杆少于4支时其高度将显著增加,对长城本体的扰动及风貌影响明显,不宜采用。提出了对游人可能接触到的接闪杆金属部位应采取防接触电压的保护措施。

While installing air-termination System in the Great Wall watchtowers in sections open to tourists,it is necessary to take into account fully not only the type and scope of protection,but also the lightning disturbance on the watchtowers and the influence on the overall outlook of the Great Wall.The installation method of lightning rods for direct lightning protection on the watchtowers is described.According to the lightning protection categories of the Great Wall and the principle of the rolling ball method,the lightning rod heights in four outer corners of different watchtowers are calculated,which should be controlled below 4.5 mto protect visitors.Simultaneously,the lightning rod heights in the watchtowers prohibiting climbing should not exceed 1m.According to the cultural relics principle of the minimal intervention on the Great Wall when installing lightning arrester,the possibilities of reducing the number of lightning rods are discussed.It is found that when the number of lightning rods is less than four,the lightning rod height will increase significantly and obvious negative effects will be brought on the appearance,so this way should not be used.In addition,the protective measures should be taken to prevent the contact voltage where visitors may come into contact with the lightning rod parts.