The laws of surface settlement and earth pressure are different in different kinds of soil when shield machine passes through. With Hefei subway shield construction as the background

model tests with typical sand and clay of Hefei region as test material are conducted to investigate variation laws of settlement and earth pressure change

which are caused by shield excavation.The results show that the sand ground is more sensitive than the clay ground to the disturbance of excavation. The change of settlement and earth pressure of sand model is much faster than that of the clay model after excavation

as well as the rate of recovery of stability. The curve of final settlement trough of sand model has more fluctuation than that of clay model. While the settlement and earth pressure of clay model change smoothly and the curve of final settlement trough of clay model is relatively smooth. For both kinds of soil model

results also show that ratios of settlement in excavation stage to final settlement are similar. The law of earth pressure decrease rate is basically identical with that of settlement rate during four experimental stages.The maximum value of settlement is observed at the formerly excavated side while the maximum value of settlement rate is at the latterly excavated side.