公路隧道复合式衬砌结构数值计算及分析

Numerical Computing and Analysis of Highway Tunnel Composite Lining Structure

针对榆树沟隧道工程实际情况,选取了3种不同的复合式衬砌结构类型进行数值计算,对初期支护和二次衬砌的内力、安全系数及洞周位移、拱顶下沉、围岩塑性区的分布等进行了分析,评价了衬砌结构的安全性。结果表明:对于Ⅱ、Ⅲ类围岩,上台阶及下台阶中央区的开挖为施工的关键工序;对Ⅳ类围岩,上台阶开挖为施工的关键工序;在Ⅱ类围岩浅埋条件下,拱顶下沉主要是由上台阶的开挖及下台阶中央区的开挖所引起;在Ⅲ类以上围岩条件下,拱顶下沉绝大部分是由上台阶的开挖所引起;洞周位移较小,最大值为18 mm,发生在Ⅱ类围岩浅埋拱脚处;围岩塑性区发展深度最大者,连通到地表,属于Ⅱ类围岩浅埋;Ⅲ类围岩墙脚处塑性区较大;Ⅳ类围岩塑性区较小。

Three composite lining structure types were chosen for numerical computing in Yushugou Tunnel. Authors analyzed the inner forces of initial support and secondary lining, safety factor, convergence of tunnel inner perimeter, vault settlement and distribution of plastic zone in surrounding rock, evaluated the safety of lining structure. The results show that the key procedure is excavation of the upper and lower center bench for Ⅱ-class and Ⅲ-class rocks; the key procedure is excavation of the upper center bench for Ⅳ-class rocks;the vault settlement is leaded almost by excavation of the upper bench and lower center bench in the situation of shallow burial of Ⅱ-class rocks;the vault settlement is leaded almost by excavation of the upper bench in adiacent rock above Ⅲ-class;the peripheral displacement is small,the max is 18 ram,in the arch corner in the shallow burial of Ⅱ -class rocks. In the shallow burial of Ⅱ-class rocks,the depth of the plastic zone is the largest, which reaches the ground surface. The depth of the plastic zone is large in the wall corner in Ⅲ-class rocks,when the depth of the plastic zone is small in Ⅳ-class rocks.