Feasibility Study On EPB TBM Applied In Typical Gravel Strata In Beijing Metro

As for the key construction parameters of EPB TBM in typical gravel strata of Beijing area, it is studied for its feasibility of EPB TBM and the typical gravel in Beijing Metro with the help of field tests, theoretical research and numerical simulation at the background of EPB TBM excavated in typical gravel strata in line9of Beijing Metro. Mechanical properties and the space distribution rules of large size gravels and boulders are analyzed.And the feasibility requirements of EPB TBM are discussed at the base of strength, permeability, grain composition, compactedness and chemical composition of typical gravel strata in Beijing Metro. According to geometric structure characteristics and construction features of EPB TBM, the theoretical calculation formulas of key parameters are introduced, and its composition and the main influence factors are proposed considering the mechanical characteristics of typical gravel strata. Through field advancing and soil conditioning tests, it is studied that the adaptability of construction parameters with soil properties, internal relationships among these parameters, as well as match relationships and adaptability characteristics of soil improver with advancing modes of EPB TBM in typical gravel strata. Finally, finite difference software FLAC3D is used for simulating the excavation process of EPB TBM in typical gravel strata. At the same time, stability features of EPB TBM tunnel face and laws of ground surface subsidence, and relationships between stability of tunnel face and support pressure are analyzed.