Influence of Different Supporting Structures on Supporting Deformation of Long and Deep Foundation Pit of Railway

In this study, the influence of different pile diameters and supporting materials on deformation characteristics of long and deep foundation pit supporting structure of railway is systematically analyzed by finite element simulation method. The research results show that the lateral displacement of diaphragm wall exceeds the safety limit of 20mm due to the lack of cross-sectional stiffness of 800mm diameter protective piles, while the displacement control effects of 1000mm and 1200mm diameter protective piles are similar, but the latter has poor economic benefits. In the selection of supporting materials, the influence of concrete bracing or steel bracing on lateral displacement of protective piles is not significant, but steel bracing has more advantages in controlling vertical displacement of deep bracing. It is also found that the diagonal brace and corner reinforcement structure can effectively restrain the corner displacement of foundation pit, and increasing the pile diameter to 1000mm can significantly enhance the restraint of soil around the pile and improve the internal force distribution of the structure. Comprehensive technical and economic analysis shows that the composite supporting scheme with 1000mm diameter protective pile and steel support can not only meet the requirements of deformation control, but also have good engineering economy, which can be used as the optimal supporting scheme for similar long and deep foundation pit projects.