Abstract��
Considering the great strength and stability of medium weathered slate, the innovative arch-cover method was successfully adopted for the first time in construction of the large-span shallow-buried bored metro stations of the Dalian metro project. Based on the design and construction of the Zhongshan Square station, the core concept and advantages and disadvantages of the arch-cover method are compared with the PBA method in this paper. After completion of the primary support at the arch, the three different construction sequences of top-down, semi-top-down and semi-bottom-up, and bottom-up were analyzed and compared in detail from the aspects of safety, quality, progress, and additional measures. Results show that the top-down method was undoubtedly the most reliable when experience and relevant data are lacking. Countermeasures against construction problems, such as a large arch spring, arch support, medial plate, drill-blasting, and steel pipe column protection, as well as surrounding rock support for the high side wall, are put forward. Finally, the optimization suggestion of the arch-cover method is presented.
2014, Vol. 51 