Soil pressures on both sides of the cutter wheel of an EPB-shield

Abstract: Soil pressures were measured on both sides of the cutter wheel of an EPB-shield during tunnelling in saturated sand, using foam for soil conditioning. The measured pressures are compared with the pressures at the pressure bulk head. The pressures are not purely hydrostatic but the results are also influenced by the yield stress in the foam. At the lowest positions, the sensors sometimes measured effective stresses. This led to peaks in the pressures measured. It is shown that for the soil conditions present, the pressures measured at the pressure bulk head are comparable to the pressures measured at the rotor. The measurements show that during rotation of the cutter wheel the pressure are higher at the site where the tooth moves upward.