The Changsha Xiangya Road River-Crossing Tunnel Project has reached another key milestone. At around 8 p.m. on October 9, the "Xingsheng" TBM safely exited the mid-river fracture zone. This means the TBM overcame a series of difficulties including high water pressure, deep overburden and complex geology, and successfully completed the crossing of the longest broken zone risk source in the section in one go, accumulating valuable construction experience for the later crossing of the overlapping area of shallow overburden and the fracture zone.

It is understood that the river-crossing shield section of the Xiangya Road River-Crossing Tunnel Project has crossed the mid-river fracture zone. The fracture zone is about 170 meters long and consists mainly of cataclastic rock, with uneven hardness and softness. During shield construction, the stability of the tunnel face in the fracture zone is poor, and the rock has a high clay content. During the crossing, clay particles increased, causing the specific gravity of the shield tunneling slurry to rise too quickly and reducing shield construction efficiency.

In response to these problems, the construction unit and the supervision unit planned ahead together and carried out inspections and deployments many times, urging the construction unit to strictly control the cutterhead rotation speed and advance speed to reduce disturbance to the stratum; control the synchronous grouting pressure and grouting quality to prevent segment flotation; and carry out secondary grouting in a timely manner to fill the gaps between segments and rock layers, ensuring safety and quality.

To reduce the risk of the shield crossing the fracture zone, personnel from the project construction, construction, design, supervision, monitoring and testing units stayed at their posts during the National Day holiday and conscientiously performed their duties to safeguard the project. The project department also established a dedicated inspection work group, assigned full-time personnel to inspect the river surface day and night, provide real-time feedback on river surface conditions, and at the same time optimize and adjust shield tunneling parameters to ensure safe and stable shield tunneling.

According to the current progress, the north-line shield tunnel is planned to achieve full breakthrough before the Spring Festival.