Method of Calculating Chamber Earth Pressure of EPB Shield

In order to calculate earth pressure in working chamber, three calculation modes which corresponding to status of elastic balanced, active limit equilibrium and passive limit equilibrium of the soil on the excavation face was built. The relationship of relative displacement between the soil in the chamber and the soil on the excavation face of shallow EPB shield tunnel was analyzed based on Rankines earth pressure theory. The threshold of chamber earth pressure values which correspond to the limit states of subsidence and upheaval were deduced and the reasonable range of the values were obtained. Combined with a shield tunnel construction practice, the theoretical and measured values are compared. The results show that the theoretical equations are valid and can provide a theoretical approach for the selection of chamber earth pressure.