Methods for Excavation of Tunnel under Biased Loading with Super-large Span and Super-large Section Passing under High-rise Building

In order to find out the speeded-up process of excavating tunnels with super-large spans and super-large sections passing under high-rise buildings,the underground industry and Trade Station of Chongqing Rail Transit Line 3 was supposed to be excavated with four methods and elastic-plastic numerical simulations were made for all the complete processes of construction accordingly.The four excavation methods are respectively the double-sided drift excavation method with first excavation on the main-building side,the double-sided drift excavation method with first excavation on the apron-building side,the single-sided drift excavation method with first upstep excavation on the main-building side and the single-sided drift excavation method with first upstep excavation on the apron-building side.The main building is the Industry and Trade Building with 22 storeys.The simulated results show as follows: With respect to super-large span and super-large section tunnels passing under high-rise buildings,the single-sided drift upstep excavation method can satisfy the deforming and stressing requirements when rational strutting and supporting measures are taken;when unsymmetrical ground surface loading exists,the double-sided drift excavation method and the single-sided drift excavation method way be adopted,and first drift excavation on the side of small loading is superior to first drift excavation on the side of large loading.The research results provide reference to similar engineering projects.