深中通道超宽钢壳混凝土沉管管节浇筑变形控制

深中通道沉管隧道是目前世界上单节管节最宽同时也是单个行车道孔最宽的公路沉管隧道，建设标准为双向八车道高速公路，部分超宽段甚至超过双向十车道，标准管节宽度为46 m，最宽管节的最大宽度达55.467 m。管节结构采用了在内外双层钢壳内填充高流动自密实混凝土的“三明治”复合结构形式，为此结构形式在中国的首次大规模应用。其管节预制精度要求高，在混凝土浇筑阶段的变形控制要求达毫米级。在混凝土浇筑过程中，为将管节内净空变形控制在10 mm以内，原设计要求在顶板浇筑过程中在管内行车道孔增设临时支撑杆措施。为此，应用精细三维有限元模拟管节的浇筑过程，考虑其三维力学效应及混凝土逐渐凝固后的承载能力，并结合混凝土浇筑布料设备的特点，寻求出满足变形验收条件和兼顾施工效率的最优浇筑顺序，并以此取消管内临时支撑杆措施的制约。最后，该浇筑顺序在首节管节E32(同时也是最宽管节)的浇筑预制中成功应用，实测结果与计算结果吻合，满足验收要求。该技术精准控制了管节浇筑阶段的变形，优化了管节预制和舾装的施工方案，取消了顶板浇筑过程的管内临时支撑杆措施，使每节管节内的一次舾装作业得以提前约1个月启动，并可与墙体和顶板浇筑作业并行，从而缩短了管节预制坞期，保障了总体工期。

Casting Deformation Control of Super-wide Steel-concrete Immersed Tunnel Tubes of Shenzhen-Zhongshan Link

The immersed tunnel of Shenzhen-Zhongshan Link is the highway immersed tunnel in the world with both the widest tube and the widest hole in a single carriageway. The construction standard is the highway with two-way four lanes (eight lanes total) and some super-wide sections even exceed two-way five lanes (ten lanes total). The width of the standard tubes is 46 m and the maximum width of the widest tube is 55.467 m. The structure adopts the “sandwich” composite structure filled with high-flow and self-compacting concrete into the double-layer steel shell, which is the first large-scale application in China. The requirements for the tubes prefabrication accuracy is high, and the deformation control at the concrete casting stage shall reach millimeter level. During the concrete casting, The original design required that temporary support rods should be added to the traffic lane holes inside the tubes during the roof casting. In order to control the clearance deformation of the tubes within 10 mm, the fine three-dimensional finite element method is applied to simulate the casting process of the tube, considering the three-dimensional mechanical effect and the bearing capacity of concrete after gradual solidification, combined with the characteristics of concrete distribution equipment, to find out the optimal casting sequence that meets the deformation acceptance and takes the construction efficiency into account. In this way, the temporary support rods measure inside the tube can be cancelled. Finally, the casting sequence was successfully applied in the casting prefabrication of the first tube E32 (the widest tube meanwhile), and the measured results met with the calculation results, satisfying the acceptance requirements. The technology accurately controls the deformation of the tube in the casting stage, optimizes the construction scheme for the tube prefabrication and outfitting, and then cancels the temporary support rods inside the tube during the roof casting. It let the primary outfitting operation in each tube can be started about one month earlier, which can be parallel to the wall and roof casting, and then shortened the dock period of tube prefabrication to ensure the overall construction period.