郑州市地铁2号线左线隧道与1、2号线联络线隧道交叉段合建，为解决其周边环境复杂及施工工期紧张的问题，在部分合建段采用矿山法扩挖盾构隧道修建大断面区间隧道的技术，即小直径盾构先通过扩挖段，并使用全环特殊钢管片拼装隧道，然后结合矿山法，采用中立柱+临时仰拱的台阶法施工工序，反向扩挖盾构隧道，最终形成大断面区间隧道。工程实践表明，采用该技术节约3个月工期，并将地面沉降控制在25.1 mm以内，取得了较好的应用效果，可为类似工程提供参考。

The connection section between left line of Line No. 2 of Zhengzhou Metro and connecting tunnel of Line No. 1 and Line No. 2 are constructed together. The surrounding environment is complicated and the construction schedule is tight. The large crosssection tunnel construction technology, mining method, is adopted to enlarge the shield tunnel. The section is bored by shield, and then the steel segments, the bench method of central pillar + temporary invert and inverse enlarging method are adopted. The construction practice shows that the ground settlement and the construction schedule have been controlled effectively. The abovementioned technologies can provide reference for similar projects in the future.