In Underground Pipe Roof Support Finite Element Analysis

Since the eighties of the 20th century, various tunnels with different scale and geological conditions are applied to the railway and highway projects and so on. This brings the underground engineering construction technology many new opportunities and challenges. While excavating tunnels under bad geological conditions, such as shallow burying, weak broken stratum, etc., the rock surrounding the tunnel may frequently lost its stability, the hole and body country rock may collapse. To guarantee the construction security and safe application of tunnel after completion, some measures such as propping up and protecting preceding have to be adopted. Pipe shed supporting method is one of most widely used method. But so far, the application of this method is yet based on the experience analogy of engineers. This has been already unable to meet the needs of underground project development at present. So, it is a very important work to analyze the behaviors of pipe shed supporting under different construction condition and geological condition based on summarizing and learning the existed research and practical achievements.The characteristics of propping up and protecting preceding in underground projects, especially the principle and current situation for pipe shed supporting is introduced in this thesis at first. The rock's stability and deformation behaviors as well as stresses in pipe shed supporting under different rock classification and construction parameters are analyzed on the analyzing platform of ANSYS with three dimension nonlinear finite element method. The Drucker-Prager criterion is adopted in these analyses. Bellow conclusions are gotten in the research: the pipe shed supporting method can improve weak surrounding rock physical properties, forming a stiffer and stronger reinforced zone. It makes the deformation in the surrounding of tunnel well-distributed, the deformation in arch top and stratum is effectively improved. It is also founded: the maximum deformation is not sensitive to the diameter and gap of pipes, but the stress in the pipe is. So, it is uneconomic only increasing pipe diameters and decreasing pipe gaps. The excavating footages have notable affect to surrounding rock deformation and stress in reinforced zone. The thickness and strength of reinforced zone have also great influence to the stability of tunnel.The data we got in this research are basically coinciding with the practical survey results, and so this essay can be a useful reference for engineering design and construction.