超大跨度隧道衬砌结构受力特征分析

Analysis of Stress Characteristics of Lining Structures in Super-Large-Span Tunnel

为研究超大跨度隧道衬砌结构受力特征,以厦门某双洞八车道隧道为依托,建立三维数值分析模型,并结合现场实测数据,研究衬砌结构受力特征以及二次衬砌荷载分担比。结果表明:(1)围岩压力作用在初期支护上的应力小于围岩初始地应力,围岩自稳能力承受了部分围岩荷载;拆除临时隔墙在二次衬砌自重作用下,初期支护内力发生重新分布。(2)初期支护分担了约90%的围岩荷载,仰拱脚部位置的分担比率在85.7%~94%之间。(3)对于地质条件较好的地层,可以对二次衬砌支护强度进行优化设计,以节约工程成本。

To study the stress characteristics of the lining structure of a super-large-span tunnel,a three-dimensional numerical analysis model was established based on a double hole eight lane tunnel in Xiamen.Combined with on-site measurements,the stress characteristics on the lining structure and the load sharing ratio of the secondary lining were studied.The study shows that:(1)the stress exerted by the surrounding rock pressure on the initial support is smaller than the initial geostress of the surrounding rock,and the self stability ability of the surrounding rock is able to bear part of the surrounding rock load;under the action of dismantling the temporary partition wall and the weight of the secondary lining,the internal force of the initial support is redistributed.(2)The initial support shares about 90%of the surrounding rock load,and the sharing ratio at the foot of the arch is between 85.7%and 94%.(3)For strata with good geological conditions,the support strength of the secondary lining can be optimized and designed to save engineering costs.