高速公路连拱隧道中墙治理方案研究

针对某高速公路连拱隧道中墙混凝土强度不足问题，采用有限元数值计算方法对连拱隧道中墙进行了计算，发现中墙的安全性不能满足规范要求。为了保证隧道中墙的安全使用，分别对全部凿除中墙和部分凿除中墙的治理方案进行了研究。结果表明：采用分段部分凿除的方案对中墙进行治理时，对初期支护影响较小，未凿除的中墙内力略有增大，对隧道整体结构影响很小；而采用全部凿除方法对中墙进行治理时，对初期支护影响较大。对施工进尺长度的研究表明，在Ⅲ级和Ⅳ级围岩区段隧道中墙治理时，一次凿除长度分别取为12 m和9 m是较为合理的。修复后的连拱隧道中墙安全性满足规范要求。

Study on treatment schemes of an expressway multi-arch tunnel middle wall

The middle wall of an expressway multi-arch tunnel is calculated by using finite element numerical method aiming at its strength deficiency. The result indicates that the safety factors of the middle wall cannot satisfy Code’s requirements. The treatment projects of chiseling away the middle wall partly and wholly are researched; the result indicates that when the middle wall is repaired by the chiseling away partly method, the treatment of middle wall will have a small impact on the preliminary lining; the inner force of the original middle wall will increase slightly which exerts a small effect on the whole tunnel structure. However, when the middle wall is repaired by the chiseling away wholly method, the treatment of middle wall will have a marked impact on the preliminary lining. The study on the length of construction indicates that when the once length equals respectively to 12 m and 9 m on the three and four grade rock mass is reasonable. The safety of the repaired multi-arch tunnel middle wall can satisfy the Code’s requirements.