Abstract: In order to study the influence of the lateral pressure coefficient on the deformation and stress characteristic of the shield tunnel joint, a threedimensional refined numerical model is developed, and the fullscale test is carried out. The sensitivity of the lateral pressure coefficient to the joint open, dislocation and the bolt stress under the conditions of normal load, overload and unload is studied. The study results show that: (1) At the normal load stage, the reduction of the lateral pressure coefficient worsens the load form of the tunnel structure, thus the joint is prone to damage easier. (2) When the lateral pressure coefficient decreases from 0.7 to 0.65 and 0.6, the maximum open of longitudinal joint increases by 1.6 times and 21.7 times respectively, and the maximum dislocation of circumferential joint increases by 2.7 times and 20.1 times respectively. (3) The longitudinal joint open and circumferential joint dislocation under unload condition is more sensitive to the variation of lateral pressure coefficient than overload condition. At the stages of "critical instability " and "ultimate failure", the bolt stresses are basically the same under different lateral pressure coefficients, which shows that the bolt stress is mainly determined by its own properties, the reduction of lateral pressure coefficient only accelerates the process of bolt yield, while has no significant influence on the final stress of the bolt.

Key words: shield tunnel, lateral pressure coefficient, joint open, joint dislocation, bolt stress, threedimensional refined numerical model, fullscale test