隧道钢筋混凝土防开裂施工技术

Anti-Cracking Construction Technology of Reinforced Concrete Tunnel

由于现有的防开裂施工技术混凝土限制膨胀率高、强度低、裂缝现象严重,为此,开展隧道钢筋混凝土防开裂施工技术研究。在隧道开挖前,搭建复拱钢架支护,运用喷射混凝土填塞缝隙。固结注浆初支围岩,形成环向保护壳。隧道开挖后,洞内反向填充,防止坍塌部位变形破坏,并喷射混凝土修复施工面。运用逐榀环形掏槽预留核心土开挖,将填充材料填入裂缝中,提升混凝土衬砌承载能力。在施工过程中,用防水砂浆整平裂缝表面,定期养护。隧道竣工后,对裂缝衬砌断面进行安全性分析和等级判定。测试结果表明,在隧道施工28 d时,混凝土强度为45 MPa,限制膨胀率为0.045%,符合预期施工效果,裂缝现象得到较好缓解。

Due to the high limited expansion rate,low strength and serious crack phenomenon of the existing anti-crack construction technology,the research on anti-crack construction technology of reinforced concrete in tunnel is carried out.Before the tunnel excavation,the steel frame support of the compound arch was built and the gaps were filled with shotcrete.The initial surrounding rock is consolidated to form a circumferential protective shell.After the excavation of the tunnel,the hole is reversed filled to prevent the deformation and damage of the collapsed part,and the construction surface is repaired by shotcrete.The core soil is reserved for excavation by one annular cut,and the filling material is filled into the crack to improve the bearing capacity of the concrete lining.In the construction process,the crack surface is levelled with waterproof mortar and maintained regularly.After the tunnel is completed,the safety analysis and grade judgment of the fracture lining section are carried out.The test results show that the concrete strength is 45 MPa and the limited expansion rate is 0.045%during 28 days of tunnel construction,which is in line with the expected construction effect and the crack phenomenon is well alleviated.