Abstract:

Due to the loose and instable property of artificiallyfilled soil strata, it is difficult to build mined tunnels in such strata. In the paper, the design of a 4arched tunnel of Beijing Metro located in artificiallyfilled soil strata is studied by means of theoretical analysis and finite element numerical simulation. Comparison and contrast is made among three construction methods, i.e., pilot method, side heading method and “pilot method + side heading method”, in terms of stress on the support structure, ground surface settlement, risk control and construction period. Conclusion is drawn that the side heading method is the optimum construction method for the project. The proposed method has been adopted for the project, which shows that the method can minimize the horizontal displacement of the central wall, bring the settlement under effective control, make the secondary lining form a closed ring as early as possible and reduce the stress on the primary support.

Key words: Beijing Metro, mined 4arched tunnel, artificiallyfilled strata, construction sequence, side heading method