I. Project Overview:

The first phase project of Tianbao Avenue West Extension Line is located in the southwest of Shuangliu District, starting from the current Chengxinpu, and ending from the Tongwei section of Huangjia Street, which has been built. The west section of the designed Industrial Park Avenue is connected to the current Shuangxing Avenue, and finally connects to the Tianfu New District directly, forming the east-west main road of Shuangliu District. The implementation of the project will set up the main road network structure in the southwest of Shuangliu District and provide conditions for the development of the surrounding plots.

The total length of the project is about 11.7km, the road grade is the main trunk road, the design speed is 60km/h, the road red line width is 40m, and the green belt is 30m on both sides (the green belt width is 15m in the local limited location). The project includes road engineering, traffic engineering, culvert engineering, bridge engineering, drainage engineering, lighting engineering, electrical engineering, landscape engineering and large road node crossing bridge.

Along the road, natural landforms such as farmland and water (canal) system are passed, and the planning nature of the surrounding area is green land, industrial land and residential land. The area along the road is undeveloped land, and the current situation is farmland. The main intersection road is Dawei Road, while Chengmian Lekezhuan and Metro Line 10 are across the project.

二、主要节点方案：

天保大道西延线一期工程主要节点有成绵乐客专节点和大件路跨线桥节点。

1）成绵乐客专节点

道路线路与成绵乐客专双流西特大桥立体交叉，交点桩号为K05+510.962，交叉处道路分两幅下穿成绵乐客专K29+555双流西特大桥，左幅道路由铁路桥172～173#墩下穿，右幅桥由173～174#墩下穿，桥下净空为5.98m和5.88m，道路与铁路交角为73.712°。

道路采用路堤形式下穿铁路桥，两侧设HA级防撞护栏，并对既有铁路桥梁中心线两侧各15m范围内桥下地基采用φ108钢花管注浆加固。市政道路配套雨、污水管、给水管由171～172#、174～175#桥墩下穿成贵客专K29+555双流西特大桥，铁路桥梁中线两侧各20m范围内管线外侧设置市政Ⅲ级管作为套管。管线套管均采用开挖直埋下穿铁路，开挖直埋管线套管外侧采用C25混凝土180°基础。

2）大件路跨线桥节点

天保大道与现状大件路相交位置，地铁10号线位于大件路中央绿化带内，该段地铁以高架桥形式呈现。该节点采用天保大道与大件路辅道平交，大件路主线设置跨线桥跨过该交叉口，跨线桥与地铁10号线并线设计。设计时考虑对地铁的影响因素，采用快速施工方式，上部采用小箱梁及钢箱梁结构，均为预制拼装构件，加快建设速度；下部采用桩基础，跨线桥桩基础与地铁桩基础间距 考虑6D（D为桩径）,减小桩基附加应力扩散后对既有地铁基础的影响，并设置长护筒防塌孔，避免施工期间桩孔垮塌引起地基局部失去支撑作用；桥面系在防撞墙外侧SX型防撞墙，并于防撞墙顶部设置声屏障，最大程度减少后期运营阶段对既有地铁高架桥的影响。本桥梁设计在满足功能需求情况下，合理利用地形地物条件，并全过程减少对既有设施的影响。