The Xiongan Express shield tunneling machine smoothly crosses the Baigou River

On Feb. 21, the Xiongan-3 shield tunneling machine of the Xiongan Express Line project smoothly crossed the Baigou River, laying a solid foundation for the tunnel connecting the section from the fifth Group station to the starting point of the viaduct. At present, the "Xiongan No. 3" shield tunneling machine has been digging 2,528 meters forward.

It is reported that the construction of Baigou river diversion section is a level of risk source, the distance between the two dike of the river is 252 meters, a total of 158 rings. The main strata through the section are silty clay and silty sand layer with shallow soil covering depth. The minimum clear distance between the section tunnel and the river bottom is 10.76 meters. The upper part of the waterproof layer is weak, if the construction is improper, it is easy to occur water gushing sand, resulting in the formation of hydraulic connectivity of the river, resulting in the collapse of the palm surface. In the construction process of the shield tunnel under the river, the soil pressure on the upper part of the segment is small, and the formed tunnel is easy to float, which leads to the unqualified quality of the formed tunnel. Riverbed settlement cannot be monitored directly and the surface settlement cannot be mastered to guide shield construction, which further increases the construction risk.

In order to ensure the smooth passage of the shield tunneling machine through the risk zone, the Xiongan Express Line headquarters of PowerChina Railway Company provided guidance and assistance for many times, invited industry experts to hold a symposium on the Baigou River crossing scheme, demonstrated the feasibility of the scheme, and fully prepared the technical scheme before the crossing. Before the crossing, the project construction team set up a test section in the 100-meter section close to the construction conditions of the tunnel and Baigou approach river. Through the test section tunneling, the scientific rationality of shield tunneling parameters was simulated under the construction conditions of the Baigou approach river, the shield tunneling parameters suitable for the Baigou approach river were summarized, and the effectiveness of various technical measures for the Baigou approach river was verified. During tunneling, the resident personnel are on duty 24 hours a day to strictly control the soil bin pressure and excavated amount during shield tunneling, ensure the ground settlement is controllable, strictly control the shield tunneling attitude and timely correct deviation, and ensure the tunnel segment forming quality.

At present, "Xiongan No. 3" has successfully crossed the Baigou river, is rushing to the hole node target. The Xiongan Express Line project will unite as one, build on the momentum, and strive for the smooth release of Xiongan No. 3.