武汉青山长江公路大桥北塔施工关键技术

武汉青山长江公路大桥主桥为主跨938m的双塔双索面全飘浮体系斜拉桥,北塔采用A形钢筋混凝土结构,塔高279.5m,由下塔柱、中塔柱、上塔柱、上横梁及塔冠等部分组成。北塔塔柱分为49个节段,标准节段长6m,采用液压爬模施工。施工时,在塔柱内设置劲性骨架,并在两塔肢间设13道临时横撑,按施工阶段对塔肢进行主动顶推。塔柱采用C55高性能混凝土,利用超高压泵将混凝土一次泵送到位。上横梁高6m,采用支架法施工,上横梁混凝土分2层(每层高3m)与两侧塔柱混凝土同步浇筑;钢锚梁采用10 000kN·m的塔吊整体吊装;上塔柱锚固区环向预应力采用深埋锚工艺施工。

Key Techniques for Construction of North Pylon of Qingshan Changjiang River Bridge in Wuhan

The main bridge of Qingshan Changjiang River Highway Bridge in Wuhan is a cable-stayed bridge with a full floating system, having a main span of 938 m, double pylons, and double cable planes. An A-shaped reinforced concrete structure with a pylon height of 279.5 m is adopted in the construction of the north pylon. The pylon consists of a lower pylon column, a middle pylon column, an upper pylon column, an upper cross beam, and a pylon crown. The north pylon column is divided into 49 sections, in which the standard length of each section is 6 m, and is constructed by hydraulic climbing formwork. During the construction, a rigid framework is set in the pylon column, and 13 temporary cross-braces are set between the two pylon limbs, thereafter, the pylon limbs are pushed forward actively according to the construction stage. Grade-C55 high performance concrete is used for constructing the pylon column, and the fresh concrete is put in place in a once-through way by using an ultra-high pressure pump. The height of the upper cross beam which is constructed by the bracket method is 6 m. The fresh concrete for the upper cross beam which is cast by two layers (3 m high per layer) is synchronously poured with casting the fresh concrete for both sides of the pylon column. The steel anchor beam is hoisted and assembled by pylon cranes with a crane torque of 10 000 kN·m. The circumferential prestress in the anchorage zone of the upper pylon column is constructed by deep-embedded anchoring technology.