Taiyuan Metro Line 1 under the Fenhe subway tunnel successfully completed the crossing

At 10:18 am on March 22, in the shield tunneling section between Yingzeqiao West Station and Taoyuan Road Station of Taiyuan Rail Transit Line 1, "Endeavour 3" shield tunneling machine slowly drove away from the influence area of the bottom of the Fen River on the right line and smoothly crossed the Fen River, which also marked the successful completion of the double-line crossing of the Fen River subway tunnel under Line 1. It is the first subway tunnel under the Fen River in Shanxi Province. When it is completed, citizens will be able to ride the subway through the bottom of the river.

During the 35-day shield construction, the shield machine cut a passage from west to east at the bottom of the Fen River on the south side of Yingze Bridge in Taiyuan. It is reported that Yingze Bridge West Station to Taoyuan Road station shield section of 1278 meters, including 310 meters Fenhe section. The shortest distance from the top of the subway tunnel to the bottom of the river is 16 meters, the deepest is 22 meters, the whole terrain is "V" shaped slope, the buried depth changes greatly. This area is in the lowest position of Taiyuan Rail Transit Line 1, with large underground water and high water pressure. The maximum pressure reached 3bar, which is equivalent to one centimeter carrying 3 kilograms of weight. The soil layer of shield tunneling in this section is medium sand, fine sand and clay. After the Fen River water penetrates for a long time, the water content of the stratum is in a saturated state, and the problems of spiral machine gushing and shield tail seal breakdown are easy to occur when the fully liquefied water-rich sand layer is tunneling, resulting in the collapse of the Fen river bed and even the risk of the shield tunneling machine being submerged by the river.

In view of the difficulties and risks, the construction team invited well-known domestic shield experts to hold an argument meeting before the shield tunneling machine crossed the Fenhe River to carry out adaptive transformation of the shield tunneling machine, optimize the setting of shield tunneling parameters according to the test section, and guide the shield tunneling construction more accurately. In shield construction, the slag is improved by using the new polymer residue improver. The shield gate was added, and deep hole grouting was performed on the segment after the shield was completed. The remote intelligent monitoring and other measures for the shield operation can ensure the formation stability and ensure the safe and efficient tunneling of the shield machine.