On August 15, as the cutterhead of the "Yuxing No. 2" TBM broke through, the Qixinggang Station–Chongqing Station TBM section (hereinafter referred to as the Qichong section) of the north extension project of Chongqing Rail Transit Line 18, constructed by Chongqing City Transportation Development & Investment Group Rail Transit Group and undertaken by China Communications Construction Company (CCCC), successfully achieved twin-tube breakthrough, and tunnel construction on the project has entered a phase of comprehensive acceleration.

It is reported that the left-line tunnel of the Qichong section in this construction phase was excavated using the 6.86-meter composite earth pressure balance shield machine "Yuxing No. 2," independently developed by CCCC. During shield tunneling, "Yuxing No. 2" had to pass alongside multiple key structures, with complex geological conditions, high construction difficulty, and stringent control standards.

According to reports, in order to ensure that the TBM safely passes through numerous risk sources, the project fully leveraged the role of the working class as masters of the enterprise and the exemplary and guiding role of model workers, establishing a technical assistance team to fight side by side with industrial workers, striving to improve the overall quality of the workforce, and using a digital system to monitor the tunneling process in real time and dynamically optimize tunneling parameters, ensuring safe and efficient TBM tunneling and setting a record of up to 8 rings excavated in a single day. To ensure stable material transport during long-distance, steep downhill construction, project technical personnel and work teams carried out multiple technical improvements, installing sleeper tie devices and track tie rods to ensure uniform sleeper spacing and straight track alignment, effectively avoiding the risk of battery locomotive runaway.

In addition, in response to the geological structure of the Qichong section, the project builders upheld the spirit of craftsmanship and, with a meticulous work attitude, made targeted improvements to the shield machine. The modified shield cutterhead consists of 44 disc cutters and 98 scraper cutters, equipped with 457.2 mm 18-inch wedge-shaped inserted-tooth disc cutters, greatly enhancing the rock-breaking capability at the front end of the shield machine. At the same time, devices such as soil conditioning and cutterhead cleaning were scientifically configured to prevent mud cake formation during tunneling, overcoming the difficulties of tunneling in complex geology.

"At present, the entire line is using the 'Three Grasps, Three Comparisons' themed labor competition as a lever, striving to sound the 'Worker Pioneer' call. From management personnel to frontline workers, everyone is tackling construction challenges step by step with the determination and confidence to roll stones up a mountain, working together tirelessly to build a subway that satisfies the people of Chongqing as soon as possible and to further improve Chongqing's rail transit network," said Chen Yunfeng.

It is reported that since entering the site, the project management team has continued to carry forward the spirit of labor, focusing on both refined management and scientific and technological innovation, leading all employees to pursue development and achieve outstanding results through innovation. They have won the "Global Outstanding Engineer Competition Silver Award" and the "Rail Transit Science and Technology Progress Award Second Prize," obtained 16 *** QC achievements, and the general contracting department has also been awarded honorary titles such as "Chongqing Worker Pioneer," "Chongqing Ankang Cup Competition Winning Unit," "Chongqing Youth Civilization," and "Chongqing Transportation and Construction Trade Union Labor Competition Advanced Team."