港珠澳大桥岛隧工程建设的科技创新和运营后应关注的若干问题

Scientific and Technological Innovation and Operation-related Issues for Island-Tunnel of Hong Kong-Zhuhai-Macao Fixed Link Project

针对当年为何在港珠澳大桥东侧主航道海域选用海底巨型沉管隧道,而摒弃不用桥梁或盾构隧道方案进行了阐释。总结了港珠澳大桥岛隧工程建设中几项位居国内外领先水平的创新科技,包括构筑人工岛时采用自稳式的巨型钢质圆筒作为施作基坑围护结构,大面积、超深度"挤密砂桩复合地基"加固处理技术,采用"半刚性管段接头","三明治"式钢-钢筋混凝土组合结构倒梯型最终接头,钢筋混凝土沉管结构的控裂和防腐耐久性设计,中国智慧、中国速度的建造技术,等等不一而足。指出了大桥沉管隧道在运营期间应关注的若干技术问题:1)大桥通车后,沉管隧道后续的工后沉降和差异沉降量是否会进一步发展?最终的收敛值又将有多大?如果超限,又应作何种管控对策? 2)如果发现有大/小管节/管段的接头张开,又该怎样应对处理?如何确保设计预期的沉管各节段间大小接头都要求做到"滴水不漏"?并提出了一些建议及管控对策:1)如果大接头工后沉降(尤其是差异沉降)超限,建议采用深水下的"微扰动注浆"进行后处理; 2)如果接头在底板处有因正弯矩值过大而张开的不测情况,认为只需截断管段顶板内的部分预应力筋,而使截面正弯矩值降低,即可将接头处已张开的底板接缝重新闭合,达到整治的效果。

The author explains why a giant undersea immersed tube tunnel was selected for the sea area of the main channel of the east side of the Hong Kong-Zhuhai-MacaoFixed Link Project,insteadofemploying abridgeor shieldtunnel;and summarizes several domestic and international leading innovative technologies applied in the island-tunnel construction of the Hong Kong-Zhuhai-IMacao Fixed Link Project,including the use of huge self-stabilized steel cylinders as retaining structure of foundation pits for constructing the artificial islands,the large-area and ultra-deep 11 sand compaction pile(SCP)composite foundation"reinforcement technology,M semi-rigid segment joints",M sandwich"steel-RC combined inverted-trapezoid closure joints,and crack control and anti-corrosion/durability design for RC tube structure,j^l these technologies reflect Chinese wisdom and Chinese speed.The author also points out some technical issues to which attention should be paid after the immered tube tunnel of the project is put into operation:(1)Will the post-construction settlement and differential settlement of the immered tube tunnel further develop after the project is open to traffic?How much is the final convergence value?If it exceeds the limit,what control measures should be taken?(2)How to deal with the issue that the joints of large/small elements or segments are open?How to ensure that all the large and small joints between segments of the tube are"watertight"?Furthermore,the author presents some suggestions and control measures:(1)For excessive post-construction settlement(especially differential settlement)spotted on large joints,it is suggested to incorporate M micro-disturbance grouting"for post treatment.(2)I a joint opens under the excessive positive bending moment at the foor slab,it is believed that the open joint on the foor slab can be closed again by cutting off some prestressed tendons in the roof slab of the segment to reduce the positive bending moment of the section.