The Function Research Of Double-row Support Piles Of The Jiuhuashan Tunnel Deep Excavation In Soft Soil Ground

The retaining structure of double-row piles is a new supporting technology developed in the 1990s of last century, which is formed by constructed two rows compactness piles encircle the excavation pit, and setting vertical and transverse firm grid at top of the piles. The structure with large lateral rigidity, no increase in the transverse of support to small displacement and need not inner sustain characteristics, also facilitate the construction and investment, with a broad application prospects compared with general support structures. However, the theory researching is not ideal and has no unitive method for designing as a new kind of retaining structure. Also, there are no response rule prescript in criterions. Especially, the researching is scarcely any in the effects of the distance between front and back row piles, rigidity of piles and beams, the properties of soil between piles, the strengthening of the passive soil area on lateral displacement and internal force of the retaining structure, further more the researching all limited in 2-D analysis, so there has limitation of the 3-D structure.A reasonable soil pressure in rear is the precondition for security and economical in design. However, the method in using currently is based on retaining wall mode, and it is not reflect the soil pressure in rear in reality. The dissertation based on the positive existent soil arching in pile-soil structure, introduce the theory of soil arching, analyze the soil arching in double-row piles, put forward the method calculate soil pressure in rear with soil arching theory. Applying the current finite element process—ADINA reappearancing the lateral displacement and internal force of the retaining structure while changing the distance between front and back row piles, rigidity of piles and beams, the properties of soil between piles, the strengthening of the passive soil area in 3-D space, bring forward a numerable proof for optimize design. At last, accomplishing the emulator simulating of deep excavation using the retaining structure of double-row piles of Jiuhuashan tunnel, proving the method in the dissertation is feasible and reasonable ,the emulator simulating is dependable, supplying valuable assist for similar projects.