摘 要

126省道南京段改扩建工程李家凹特大桥是扩建工程的命脉，是机场二通道全线能否贯通，正常运营的重要节点，李家凹特大桥所在施工标段的主要构造物为：李家凹上下匝道主线桥1座，桥长1220.2米；李家凹上下匝道桥4座，桥长749.8米。

李家凹特大桥现浇箱梁采用的是满堂支架法施工，现浇箱梁满堂支架法施工是一种首先密布搭设起支撑作用的脚手架，支模后现场进行浇筑的施工方法。本次李家凹特大桥现浇箱梁的支架搭设采用的是碗扣式支架。本设计计算书首先提出了针对本工程的支架布设方案：本次现浇箱梁的满堂支架搭设设计方案采用的支架梁钢管尺寸规格均为Φ48×3.0。纵桥向支架布设方案：纵桥向支架在靠近支点0.6米的范围内采用钢管间距为0.3米的步距进行布设，其余箱梁段均采用0.9米的步距进行布设；横桥向支架布设方案：横桥向支架在靠近腹板1.8米的范围内采用间距为0.6米的步距进行布设，其他各部位的支架均采用间距为0.9米的步距进行布设，保证承载力满足施工要求。水平步距均采用1.2米标准值。纵向、横向和水平向都需要设置剪刀撑加强支架整体的稳定性，水平上下都需要设置水平剪刀撑，使支架成为整体。使用调节螺杆与钢管轴心连接，作用在横杆上的荷载也会通过下碗扣传递给立杆，可以充分利用钢管的轴心受压能力较大的优势。支模的大龙骨采用的是10×10cm的方木立向搁置在立杆的调节螺杆上，方立木的间隔为20 cm，调节螺杆插入立杆保持轴心受力；在大龙骨上再放置10×5cm的方木作为小龙骨，间距25cm作为横肋，小龙骨上铺18mm的竹胶合板。随后，从全桥的横截面中选取了三个截面形式比较具有代表性的横截面，从承载力、碗扣式钢管支架立杆强度及稳定性、满堂支架整体抗倾覆、箱梁底模下横桥向方木、底模板、地基承载力等多个性能指标进行了充分的验算，较为完整地验证了本设计计算书所提出的支架布设方案的合理性和可行性，进而论证了本设计方案在桥梁现浇箱梁全线施工范围内的适用性。

关键词：现浇梁满堂支架法；碗扣式支架；步距；支架立杆强度及稳定性；支架整体抗倾覆性

Design of Cast-in-place Box Girder Bracket for Lijiawed Super Bridge in Nanjing Airport

ABSTRACT

The Lijiadun Bridge, a reconstruction and expansion project of the 126 provincial highway, is the lifeblood of the expansion project. It is an important node for the normal operation of the second channel of the airport. The main structure of the construction section of the Lijiadun Bridge is: Lijiawa Upper and Lower Ramp Main Bridge 1 seat, the bridge length is 1220.2 meters; Li Jiawa has 4 bridges above and below, and the bridge length is 749.8 meters.

The cast-in-place box girder of the Lijiadun Super Bridge is constructed by the full-frame method. The cast-in-place girder full-frame method is a construction method in which the first scaffolding is used to support the supporting structure. The bracket of the cast-in-place box girder of the Lijiadun Super Bridge is a bowl-shaped bracket. This design calculation book first proposed a bracket layout scheme for this project: the size specifications of the bracket beam steel tubes used in the design of the full-stand bracket erection of the cast-in-place box girder are all Φ48×3.0. Longitudinal bridge-to-bracket layout: The longitudinal bridge is laid at a distance of 0.6 m from the support near the fulcrum, and the other box girder sections are laid with a step of 0.9 m; the cross-bridge is laid to the bracket: The cross-bridge is arranged with a pitch of 0.6 m in the range of 1.8 m near the web. The brackets of other parts are laid with a step of 0.9 m to ensure the bearing capacity meets the construction requirements. The horizontal step size is based on a standard value of 1.2 meters. The longitudinal, lateral and horizontal directions need to be provided with scissors to strengthen the overall stability of the bracket. Horizontal and horizontal scissor support is required to make the bracket as a whole. The adjustment screw is connected to the axial center of the steel pipe, and the load acting on the cross bar is also transmitted to the vertical rod through the lower bowl buckle, which can fully utilize the advantage that the axial pressure of the steel pipe is large. The large keel of the formwork is made of 10×10cm square wood standing on the adjusting screw of the pole. The spacing of the square standings is 20 cm. The adjusting screw is inserted into the pole to maintain the axial force; and the upper keel is placed on the large keel. ×5cm square wood as a small keel, with a pitch of 25cm as a transverse rib, and a small keel with 18mm bamboo plywood. Subsequently, three cross-sections with special cross-sections were selected from the cross-section of the full bridge, from the bearing capacity, the strength and stability of the bowl-type steel pipe support poles, the overall anti-overturn of the full-frame bracket, and the cross-bridge under the box girder bottom mold. A number of performance indicators such as square wood, bottom formwork and foundation bearing capacity were fully checked, which verified the rationality and feasibility of the bracket layout scheme proposed in this design calculation book, and further demonstrated that the design scheme is Applicability of the entire cast-in-place girder bridge construction scope.

Key words：Cast-in-place beam full bracket method; bowl button bracket; step; bracket pole strength and stability; bracket overall anti-overturning

目 录

1、工程简介 1

1.1工程简介 1

1.2现场施工图调整情况 2

1.2.1李家凹上下匝道主线桥 2

1.2.2李家凹上下匝道LU2、RD2匝道桥 2

1.2.3李家凹上下匝道RU2、LD2匝道桥 2

2、碗扣式支架介绍 3

2.1碗扣式支架介绍 3

2.2碗扣式支架的特点及优势 3