曹家沟黄土大断面隧道施工参数优化研究.pdfVIP

Subject : Study on Construction Parameter Optimization of Large Cross-section Loess Tunnel Cao-jiagou Specialty : structural engineering Name : Li Bao-ping (Signature) Instructor : Wang Xiao-lin (Signature) ABSTRACT The design, construction and operation of large cross-section of loess tunnel often encounter a number of difficulties and problems due to its large area and unfavorable conditions of surrounding rocks. The loess tunnels at the present day are often constructed with traditional methods which are featured by complex procedures and slow progress. Whereas the three-bench seven-step excavation method can display its unique advantages under such geological conditions. But the study on the optimization of construction parameters is far from adequate, which becomes an important topic for study in the project of large cross-section loess tunnel. This thesis summarizes the properties of loess, deformation features, surrounding rock pressure and major disasters of loess tunnel. Apart from the study on the definition and construction methods of a large cross-section tunnel, it makes comparison of the traditional construction methods of loess tunnel and proves the reliability of three-bench seven-step excavation method applied in Cao-jiagou Tunnel project. Then it focuses on the process and main points of three-bench seven-step excavation method. Drawing the experience of the large cross-section loess tunnel of the ongoing Cao-jiagou railway project, it takes numerical simulation analysis on the supporting