Effect of insufficient tunnel crown thickness on the post-tensioned concrete lining of the Yellow River Crossing Tunnel and its strengthening schemes  

拱顶欠厚对穿黄隧洞预应力混凝土衬砌的影响及加固方案（英文）

作　　者：Qin Gan Cao Shengrong Lai Xu Yang Fan 秦敢;曹生荣;赖旭;杨帆(武汉大学水资源与水电工程科学国家重点实验室,武汉430072)

机构地区：State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China

出　　处：《Journal of Southeast University(English Edition)》2018年第3期356-363,共8页东南大学学报（英文版）

基　　金：The Natural Science Foundation of Hubei Province(No.2017CFB667);the National Natural Science Foundation of China(No.51079107)

摘　　要：The effect of deficiency in tunnel crown thickness on the Yellow River Crossing Tunnel with post-tensioned concrete inner lining was investigated by the elasto-plastic finite element method. Changes in the deformations and circumferential stresses of the post-tensioned concrete inner lining with the gradual decrease of the tunnel crown thickness were compared, and the potential bearing risk of insufficient tunnel crown thickness for the Yellow River Crossing Tunnel was revealed. Based on the finite element calculation results of circumferential stresses under different defective cases, the corresponding reinforcement schemes were proposed. The calculation results show that the inner lining can still maintain a satisfactory stress state when the tunnel crown thickness is equal to or greater than 0. 28 m. When the tunnel crown thickness decreases below 0.28 m, the external surface of the crown and internal surface of the crown＇s adjacent areas may be under tension. The tension stresses will incrementally increase and ultimately exceed the tensile strength of the inner lining concrete as the tunnel crown thickness further decreases gradually. Then, the Yellow River Crossing Tunnel cannot operate normally, and severe cracking, leaking or even failure may occur. When the tunnel crown thickness is equal to or greater than 0.28 m, the reinforcement suggestions are that the void spaces between the inner lining and the outer lining should be back-filled with concrete. When the tunnel crown thickness is less than 0. 28 m, the inner lining should be reinforced by steel plates after concrete back-filling.针对南水北调中线穿黄隧洞,采用弹塑性有限元方法,研究拱顶欠厚对穿黄隧洞预应力内衬结构的影响.对比衬砌拱顶发生不同欠厚条件下预应力内衬的变形和应力变化情况,以此揭示拱顶欠厚对穿黄隧洞带来的潜在承载风险,并根据不同欠厚条件下的内衬应力计算结果,提出了相应的预应力内衬结构的加固方案.研究结果表明:拱顶厚度大于等于0. 28 m时,预应力内衬的应力状态良好;拱顶厚度小于0. 28 m时,内衬拱顶的外表面以及拱顶内表面的附近区域会出现一定范围的拉应力区,并且随着拱顶厚度的继续减小,拉应力会逐渐超过内衬混凝土的抗拉强度,造成预应力内衬开裂、漏水,从而会对穿黄隧洞的安全运行带来不利影响.对于拱顶厚度大于等于0. 28 m的情况,可采用拱顶回填混凝土的方式对结构进行加固;对于拱顶厚度小于0. 28 m的情况,建议在拱顶进行回填混凝土处理后。

关 键 词：post-tensioned concrete linings runnel crownthickness stress redistribution finite element analysis tunnelreinforcement Yellow River Crossing Tunnel 

分 类 号：TV332[水利工程—水工结构工程]