The application of ductile yielding elements for precast lining segments

Abstract: In the process of tunneling with shield TBMs the annular gap is backfilled with pea gravel or mortar according to the ground conditions. Due to the operational procedure an unfavorable bedding situation of the annular gap often leads to ovalization and accompanying damages of the segmental lining. With voluminous stress induced failure and the lack of necessary relaxation space local overstressing also leads to a damaged segmental lining. Based on a concept study a yielding element has been developed to improve the bedding situation. The basic idea of this concept is the yielding potential in radial direction. A clamping mechanism guaranteeing the load transfer between yielding elements and segmental lining has proven to be simple and efficient.