Study on the dynamic construction mechanics of side piles in metro station using the pile-beam-arch method

Based on the Tianhe East Station in Guangzhou Metro Line 11 engineering, this paper analyzes the formation mechanism of soil arching effect (SAE) of station by pile-beam-arch (PBA) method in the excavation process and studies the mechanics and deformation laws of side piles in different construction stages under different pile spacing conditions. The results show that the formation, development and destruction of SAE between piles are closely related to construction process. Both too large and too small pile spacings are not conducive to the development about SAE between piles; when it is located between them, the SAE between piles exerts greatly. In the form of composite lining system, supporting piles as well as SAE between piles play an effective role in supporting soil behind piles. The lateral deformation of pile body is most significant in the completion of buckle arch to the excavation of first soil layer, which is the critical construction phase to reduce lateral deformation of side pile. The axial forces of side pile increase gradually with the excavation of station, and the change is the most drastic at the excavation for first soil layer. The influence of pile spacing on vertical settlement and axial force of side piles is much greater than that of horizontal displacement and bending moment.