Dynamic coupling simulation of shield construction mechanics considering characteristics of soils

The soils are a transfer medium between supporting force of excavation face and earth pressure of soil chamber, and their performance directly affect the control of earth pressure of soil chamber, the supporting force of excavation faces, and the deformation of soil stratum, and subsequently the stability of surrounding buildings. Through the preparation of coupling procedures between discrete element and finite difference element, the dynamic excavation process of earth pressure balance shield is realized, and the effects of soil conditioning on transfer of earth pressure and response of excavation surface formation are analyzed. The results show that the earth pressure of soil chamber is not a stable value, which is a certain range of fluctuations, and the closer its distance to the cutterhead, the greater the pressure fluctuations in the process of shield tunneling. Under the excavation of shield machine, the rotation angle of cutterhead has certain influences on the internal and external earth pressures of soil chamber. The pressures are relatively large when the panel of cutterhead goes to the horizontal line of the monitoring point, whereas they are relatively small when the opening of cutterhead goes to the horizontal line of the monitoring point. The soil conditioning increases the transfer coefficient, which is not a constant, but a variable value affected by the rotation angle of cutterhead, and it reduces dispersion of earth pressures.