成都地铁1号线和2号线一期，均用“国外盾构”完成隧道施工。面对成都隧道地质的复杂性、特别是盾构施工大面积富水砂卵石地层的世界难题，同时因“国外盾构”在地铁1号线和2号线使用中存在适应性不足及难以改进，在充分汲收实践经验的基础上，决定设计制造国产化的“中铁盾构”。重点有针对性地对盾构主驱动及刀盘设计、开口率、渣土改良、螺旋输送机系统等进行优化设计研究。通过与“国外盾构”历时2年的对比实践验证，“中铁盾构”能够在全断面富水砂卵石地层长距离持续掘进，安全优质、高效可控，具有更强的适应性和更高的可靠性。

No. 1 Line and Phase I Project of No. 2 Line of Chengdu Metro are constructed by foreign shields. These foreign shields, which are difficult to be optimized, cannot be well adapted to the actual conditions of the project. Therefore, CREC shields are designed on basis of the complex geological conditions in Chengdu, especially the waterrich sandcobble strata. In the paper, study is made on the optimized design of CREC shields in terms of main drive, cutter head design, opening ratio, ground conditioning and screw conveyor. The comparison and contrast between foreign shields and CREC shields shows that CREC shields have good adaptability, reliability and efficiency and can achieve continuous longdistance boring in fullface waterrich sandcobble strata.