ABSTRACT
The installation of segmental linings within a tunnel requires skilled personnel and is often aided by the use of connection elements at radial and circumferential joints. Despite this, during the ring assembly, shoving and grouting, small imperfections in the geometry of the ring, such as ovalisation, lipping and stepping occur. These imperfections, known as imperfect build, are crucial for design. Standard practice models the segmental lining as perfectly circular and then superimposes the effects of the imperfect build on internal forces only at joint locations. This paper investigates the impact of imperfect build on internal forces by comparing segments in a perfect circular ring to those in an ellipsoidal shape using numerical analysis. It examines how bending moments induced by joint rotational misalignment are distributed into the segment. Various parameters, such as ovalisation magnitude, ground stress, and stiffness, are considered. Results show that ground stiffness and stress anisotropy significantly affect bending moment distribution.
