A Fast Estimation Method of Soil Discharged by an Earth Pressure Balanced Shield Machine

Abstract

The soil discharged by an earth pressure balanced (EPB) shield machine reflects ground loss and controls surface settlement. In engineering, the discharge was mainly estimated by weighing the tunnelling spoil, however, human disturbance and information lag bring serious hidden security risks to tunnel construction. Through the analysis of conveying flow and force of screw conveyor, an energy model of interaction between screw conveyor and soil discharged was proposed and verified experimentally. Then, the energy model was combined with the discharge equation and the force balance equation, and a semi-analytical method to fast estimate the soil discharged of the EPB shield machine was proposed. Taking an EPB shield construction project as an example, according to the data of earth pressure, the torque and the rotation of the screw conveyor recorded by EPB shield machine, the real-time soil discharged of EPB shield machine can be accurately estimated. The mean absolute error (MAE) of this method is 3.177 × 103 kg compared with the measured weight of tunnelling spoil, which verifies the rationality of the method and provides a method for further effective evaluation and control of ground loss.