Abstract：A large-scale shield experimental platform and a shield model with diameter of 1.8m are considered to simulate the earth pressure around shield machine. Excavation experiments of shield model are conducted in clay，sand and gravel soils. Two different open ratios of 30% and 70% of cutter head，respectively，are applied to the model experiment. The working parameters including thrust force，torque of cutter head and earth pressure of soil cabin are collected during the processes of excavation. Special attentions are focused on the change of earth pressure and effects of open ratio on cutter head with different earth pressures inside and outside of soil cabin. A finite difference model is constructed for the numerical analysis of excavation process，in which the effect of open ratio of cutter head is considered carefully. This numerical model gives the dynamic change of earth pressure in the soil around the shield model；and the calculated values are compared with those monitored in the model experiment.
