北京五环路京山立交桥钢箱梁架设施工方案.doc

北京五环路京山立交桥钢箱梁架设施工

　　北京五环路是北京市2003年度重点工程建设项目，它是一条截流、疏导过境交通，连接市区边缘集团的一条重要交通干线。由中铁十九局集团第三工程有限公司负责施工的五环四期第五合同段在K9+155.178处上跨京山铁路，该桥全长824 米，分左右两幅，全宽28.5m，位于R=1050m的平曲线及R=10000m的竖曲线上，其中跨越京山铁路的第7～9孔采用 48m+72m+48m米的钢混组合连续箱梁的结构型式，单幅分3轴，共6轴，由于在交叉处主线与京山铁路斜交（交角32°），为了保证钢梁拼接处的临时支墩与铁路平行，每轴分7个节段，全桥共42个预制拼接段，梁高2.5m，最大长度为35m，最大吊装重量为59t。
　　该桥上跨京山上行、下行，京津三线，丰西四线共四条铁路正线，运输十分繁忙，昼夜通行客货列车298趟，平均每5 分钟就有一列火车通过，由于跨线作业，既不能危及行车安全又要保障运营时间，因此架设钢梁的安全性和可行性便显得尤为重要。在施工之前我们除了协调与铁路运营部门的关系申请要点外，同时对架设方案进行了深入细致的研究，确保架设的安全性和可行性。
　　根据现场地形情况，充分考虑到铁路行车限界的要求，我们选择采用在梁段拼接点平行于铁路行车方向搭设临时支墩，同时沿主线两侧切线方向搭设架梁轨道梁，采用郑州大方DF40m/100型架桥机进行架梁作业的梁体架设方案（见后附图）。具体施工方案及施工验算如下：
　　——钢箱梁临时支墩施工：
　　地基处理：由于该处地基承载力较低，实测地基承载力 150Kpa,而临时墩的荷载为110t,受铁路限界的影响，基础又不能无限扩大，因此为了保证地基承载力满足施工要求，我们采用了12%的石灰土对地基进行处理，使地基承载力达到200Kpa以上。
　　基础施工：为了提高地基土的水稳性，保证地基整体受力，减小地基不均匀沉降的影响，在处理完的地基上我们施做了一层80cm厚的C25混凝土基础。每个
Beijing Jingshan Fifth Ring Road overpass steel box girder erection

Fifth Ring Road of Beijing, Beijing 2003 is the key construction projects, it is a closure, to ease cross-border traffic, connecting the urban fringe groups an important transport route. Central Railway 19 Bureau Group Third Engineering Co., Ltd. for construction of the fifth contract segment rings 4 Department on the cross in the K9 +155.178 Jingshan railway bridge length 824 meters, about 2 minutes, the whole width of 28.5m, at R = 1050m flat curve and R = 10000m of vertical curve, which Jingshan railway across the first 7 to 9 holes with 48m +72 m +48 m m composite continuous steel-concrete box beam type, sub-3 Single-axis, 6-axis, as in the Main Line and the intersection of Jingshan Railway Skew (angle 32 °), in order to ensure the temporary supporting steel beams and Stitching the railway parallel to the axis points of each segment 7, a total of 42 prefabricated full-bridge connection section , high beam 2.5m, maximum length of 35m, the maximum lifting weight of 59t.
The bridge across Jingshan uplink, downlink, Beijing and Tianjin three lines, four lines of four abundance West Main Line railway, transport very heavy passenger and freight trains pass 298 times a day and night, every 5 minutes there is a train passed, since cross-line operations, can not endanger traffic safety and also protect the hours of operation, so setting up the safety and feasibility of beam it is very important. Before the construction of our addition to coordinating the relationship with the railway operations for points, the same time, set up an intensive program of study, to ensure the safety and feasibility of setting up.
According to the site topography, and fully take into account the requirements of railway traffic bound, we choose to use the Beam splice point the direction parallel to the erection of temporary supporting rail traffic, while the main line on both sides of the tangent direction along the erection of girder beam, with Zhengzhou generous DF40m / 100 machine girder bridge beam erection operations program (see below photo). Checking the specific construction plan and construction are as follows:
- Construction of temporary supporting steel box girder:
Ground handling: because of the low bearing capacity, the measured bearing capacity 150Kpa, load the temporary pier for the 110t, by the railway gauge the impact of base can not be indefinitely expanded, so in order to ensure the bearing capacity to meet the construction requirements, we use 12% of the limestone soil on the ground for processing, the foundation bearing capacity to 200Kpa above.
Foundation Construction: To improve the water stability of soil to ensure that the whole force foundation, reducing the differential settlement of foundation, finished with the foundation we have done applied a layer of 80cm thick C25 concrete foundation. Each