某高速公路深埋隧道支护结构安全评估与分析

Safety Assessment and Analysis of Lining Structures of a Deep-buried Tunnel in Mountainous Expressway

依托贵州省荔蓉高速公路姑两隧道,对深埋条件下分离式隧道的支护结构进行受力性能分析和安全评估。利用围岩极限拉应变准则反演得到各级围岩的计算参数,通过建立埋深最大断面隧道的有限元数值模型,详细分析了隧道衬砌和锚杆的受力性能及变形,并基于结构极限状态理论对支护体系进行了安全评估。研究结果表明,隧道拱顶沉降和洞周水平收敛均在规范允许范围内,正常使用极限状态可以满足。衬砌最大轴力和最大弯矩出现在拱脚位置处,该位置有十分明显应力集中,导致其最大应力远超混凝土许用应力。须在衬砌拱脚进行局部加固,或采用更为圆润的过渡曲线,以保证衬砌结构的安全可靠。

This study is based on Guliang Tunnel of Lirong highway in Guizhou Province,to analyze the mechanical properties and safety of supporting structures of the deep-buried tunnel.The principle of ultimate tensile strain was employed to make reverse analyses to acquire the calculation parameters of the surrounding rock for the following numerical simulation.The Finite Element model of the tunnel with the deepest-buried cross section was built,and the mechanical and deformation properties of tunnel supporting system were analyzed.Ultimate conditions were considered to make safety assessment of the tunnel supporting structures.Results showed that,crown settlement and horizontal convergence of the tunnel lining are all in the allowable range.The largest axil force and bending moment of lining are located at the skewback,which bringobvious stress concentration,leading to potential failure of the concrete material.Strengthen treatment or smoothing processing at the skewback of lining is suggested to guarantee the safety and reliability of the tunnel lining structure.