Soil conditioning under London

摘要

The viability of earth pressure balance machines (EPBMs) to excavate large diameter tunnels in challenging ground conditions while maintaining good control of ground movements has often been demonstrated. However, serious difficulties with the operations of these machines still arise, sometimes leading to excessive ground settlements, large sinkholes, or even loss of the face stability. These difficulties almost invariably result from poor control of the supporting pressure applied to the tunnel face, which in EPB, is substantially provided by the confinement of the excavated ground under pressure in the head chamber.