Pressure balance TBM tunneling has advanced to the point where it is routine to essentially match the face and annulus pressures around the TBM envelope. Resulting ground deformations are sensitive to the face pressure-effective stress ratio. The loading on segmental lining is impacted by this, and specifically the degree of pre-convergence, i.e., the relaxation and arching of the ground prior to lining installation. With very little information on the convergence-confinement relationship in pressure-balance TBM situations. This paper addresses the loading on precast segmental lining during pressure balance TBM tunneling based on lining load data from the Northgate Link project.
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