山岳隧道采用新奥工法(NATM)设计时，部分专家认为衬砌通常于围岩收敛稳定后施工，因此不需考虑稳定上之功能，可采无筋方式设计。而台湾地区目前之设计，通常认定衬砌会承受部分岩压及水压。在诸多设计案例中，设计岩压约为一次支撑设计载重之25%~40%。不排水隧道在较高岩覆且高地下水位之情况下，通常将静水压折减后设计。理论上，衬砌之内力以轴压力为主，采用无筋或有筋之混凝土设计，皆能提供相当余裕之安全系数，但无筋混凝土容易造成混凝土龟裂而无预警掉落，因而衬砌配置钢筋有其必要性。参考台湾地区诸多设计案例及混凝土设计规范，探讨衬砌之设计及钢筋量应用等课题。

Based on the design concept of NATM in mountainous tunnelling, the fact that concrete linings are usually cast after ground convergence under the effect of primary supports is widely recognized. Therefore, concrete linings, which concern no stability function, could be none reinforced. However, in Taiwan, it is usually considered that concrete linings would still sustain partial forces from surrounding ground and groundwater. There are many cases which concrete lining are designed with ground loadings 25%~40% of that in primary supports. In undrained tunnels under high overburden and groundwater table, the estimated external water pressure is also deducted based on full groundwater pressure. While tunnel linings are mainly resisted axial compression forces, whether designed with reinforcement or not, they can provide quite sufficient safety factors. Because none reinforced ones are easily cracked, spalled and fell suddenly, concrete linings still to be reinforced. This paper, refers to many design cases and codes in Taiwan, tries to study the design issues on concrete lining and rebar allocation.