8月18日，中铁电气化局铁路分公司工作人员在现场庆祝。当日，北京地铁7号线欢乐谷景区站至南楼梓庄站区间左线首台盾构机成功出洞，标志着全长622米的“欢南区间”左线顺利贯通。新华社发（胡斌 摄）     August 18,，China railway electrification railway branch bureau of personnel in the field to celebrate。On that day，Beijing subway line no. 7 happy valley scenic area station to station collapsed catalpa chong left line between the first computer to shield machine success out of the hole，Marks the total length of 622 meters“Huan south interval”Left line smoothly through。The xinhua news agency hair（Hu bin perturbation）