FLAC-(3d) Numerical Simulation And Theoretical Research Of The Composite Soil Nailing

Composite soil nailing's theoretical research lags behind the engineering practice, and the interaction mechanism of its each part is still not very clear, therefore, its theoretical research's development is of great significance in providing theoretical basis and promoting engineering application. So, its numerical simulation and theoretical research are conducted in this paper.In the numerical simulation part, models are built by FLAC 3D, where the soil nailing's parameters are got from pullout tests. Mohr Coulomb model and modified Cam Clay model are established according to investigation report. Mohr Coulomb model is used to analysis composite soil nailing's stability, while modified Cam Clay model is used to analysis its displacement and internal force. The effect of soil nailing, prestressed anchor, the surface of shotcrete, micro pile and waterproof curtain are considered in these models, which are solved according to excavation steps. The internal force, displacement and stability of soil nailing are analyzed, and the influences of combination factors on soil nailing are compared and analyzed.The theoretical research part's mainly about soil nailing's simplified calculation. Combining stagewise soil nailing wall's earth pressure calculation method with increment method to calculate soil nailing's axial force after each step of the excavation, this is the simplified calculation method of soil nailing's axial force. The maximum displacement can be calculated from the earth pressure mentioned above, horizontal displacement calculation of pole system FEM, which is more detailed is also carried out. Soil nailing's arrangement forms under different excavation depths are summarized; its rationality is verified through the numerical simulation.Engineering measurement, numerical simulation and theoretical research results are combined to verify its validity and practicability.