Z形刚架半棚式明洞方案比选和设计分析

为了选择落石威胁下的严重偏压地形地段的合理工程方案,满足工程美学和环保要求,通过各种方案比选,提出一种新型结构形式—Z形刚架半棚式明洞。针对落石冲击荷载进行计算分析,分析结果表明:在各种冲击角度下,冲击荷载小于1800 k N时,各部位第一主应力均小于混凝土抗拉极限强度;Z形刚架半棚式明洞具有较强的抗落石冲击能力,具有较好的安全性。Z形刚架半棚式明洞具有开挖小,能承受落石荷载较大,受力特性较好,结构美观,对沿途景观和植被破坏小,施工较为方便等优点,具有较好的应用前景,可给隧道设计、施工和研究提供有益的借鉴和参考。

Scheme Comparison and Design Analysis of Semi-shed Open Cut Tunnel with “Z”-shaped Frame

In order to select reasonable engineering scheme for serious bias terrain area under rockfall threat and to meet the requirements for engineering aesthetics and environmental protection,this paper proposes a new type of semi-shed open cut tunnel with "Z "-shaped frame on the basis of scheme comparison. The results of the simulation analysis of rockfall impact load show that the first principal stress in every part of the structure is less than the ultimate tensile strength of concrete at variety of impact angles when the impact load is less than 1 800 k N. The open cut tunnel of semi-shed with "Z"-shaped frame has strong ability to resist rockfall impact and good safety performance. It has such advantages as less excavation,good bearing capacity for rockfall,good mechanical performances and fine shape,with less damage to the landscape and vegetation along the road. It is also featured with construction convenience and wide application,and may serve as reference for design,construction and research of the tunnel.