针对目前无导洞法双连拱隧道普遍存在先行洞二次衬砌开裂问题，如何改善其受力特征以保证隧道施工及运营期间的安全性是本文研究的重点。以宜金高速黄角坪隧道工程为背景，采用数值计算方法，重点对先行洞初支厚度、钢拱架间距和二衬厚度等支护参数对先行洞围岩位移、初支和二衬受力特征的影响开展深入研究，提出了合理优化的支护参数。研究结果表明：随着初支厚度增大或钢拱架间距减小，先行洞围岩位移、二衬主应力不断减小，初支主应力不断增大，其中二衬最大拉应力显著减小，初支厚度为0.28 m或钢拱架间距为0.5 m时较最不利情况减小了15%左右。随着二衬厚度增大，先行洞围岩位移、初支和二衬主应力均显著减小，其中二衬最大拉应力减小尤为显著，二衬厚度为0.7 m时较二衬厚度为0.5 m时减少了23.8%。因此适度增大初支厚度或减小钢拱架间距，同时增大二衬厚度可有效改善二衬受力，建议V级围岩浅埋状态下先行洞初支厚度取0.28 m，对应钢拱架型号I22b，钢拱架间距取0.5 m，二衬厚度取0.7 m。

In response to the common problem of secondary lining cracking in double-arch tunnel without middle drift, how to improve its mechanical characteristics to ensure the safety of tunnel construction and operation is the focus of this study. Based on the arch section of Yijin Expressway Huangjiaoping Tunnel Project, numerical simulation method was adopted, the influence of support parameters such as the thickness of the initial support, the spacing of the steel frame, and the thickness of the secondary lining of the advanced tunnel on the displacement of surrounding rock, the mechanics characteristics of the initial support and the secondary lining of the advanced tunnel were deeply studied, and reasonable and optimized support parameters were proposed. The results show that as the thickness of the initial support increases or the spacing of the steel frame decreases, the displacement of the surrounding rock of the advanced tunnel and the principal stress of the secondary lining continue to decrease, and the principal stress of the initial support continues to increase. Among them, the maximum tensile stress of the secondary lining decreases significantly. When the thickness of the initial support is 0.28 m or the spacing of the steel frame is 0.5 m, the maximum tensile stress decreases by about 15% compared with the most unfavorable condition. As the thickness of the secondary lining increases, the displacement of surrounding rock, the principal stress of the initial support and the secondary lining of the advanced tunnel decrease significantly. Compared with the thickness of the secondary lining of 0.7 m and the thickness of the secondary lining of 0.5 m, the maximum tensile stress of the secondary lining is reduced by 23.8%. Therefore, moderately increasing the thickness of the initial support or decreasing the spacing of the steel frame or increasing the thickness of the secondary lining can effectively improve the stress of the secondary lining. It is suggested that the thickness of the initial support of the advanced tunnel should be 0.28 m, the spacing of the steel frame should be 0.5 m, the corresponding steel frame type is I22b, and the thickness of the secondary lining should be 0.7 m under the shallow buried state of V-class surrounding rock.