Abstract：The tunnel-type anchorage of Siduhe Bridge is used for the first time in large-span suspension bridge in China. Based on the rockmass parameters from tests，the three-dimensional elastoplastic analysis has been performed to simulate the complete sequence of construction including highway tunnel excavation，tunnel-type anchorage excavation，concrete in-situ casting，prestressed concrete anchorage，main cable installation，etc.. By using 8-node 3D brick elements，the surrounding rockmass and concrete anchorage bodies are simulated. Shotcrete and lining are simulated by 4-node shell elements. A modified Mohr-Coulomb model is adopted for the rockmass. Stress relaxation in surrounding rock due to excavation is simulated by field-dependant deduct elastic modulus method. The maximum vertical displacement of the top rock is 2.3 mm and that of the bottom rock approximates zero after anchorage concrete being cast. The displacements of the surrounding rock are independent of each other under designed cable force；and the displacement field approaches to same when the cable being overloaded. The failure pattern is that two anchorage bodies are pulled out which decline outsides. The magnitude of displacements in the surrounding rock is graded in mm，which is far below the allowance value of displacement on tower top. The results of the numerical analysis are used in the design of the tunnel-type anchorage.
