Abstract:

The stabling siding section of the running tunnel from Taipingjiao Park Station to Yan’ansanlu Station on Line 3 of Qingdao Metro is a large crosssection shallow tunnel to be constructed by double side heading method. If the conventional double side heading method is adopted, there is great risk in the support dismantling and it is difficult to erect the falsework for the secondary lining. Therefore, core rock is kept in the double side heading method. During the construction of the tunnel, monitoring is strengthened so as to provide guidance for the tunneling. In the end, the tunnel has been built successfully. Conclusions drawn are as follows: 1) Compared to the conventional double side heading method, the innovative double side heading method can reduce the quantity of the support to be dismantled, and can improve the safety coefficient and the construction efficiency; 2) The monitoring data show that the ground surface settlement induced can meet relevant requirements, which indicates that the innovative double side heading method is suitable for the construction of urban Metro works.

Key words: Qingdao Metro, excavation, large span, double side heading method, core rock