Failure mechanism of tunnel lining joints and bolts with uneven longitudinal ground settlement

• A numerical model with 3D lining rings and bolts considering interactions was developed.
• The progressive failure of bolts and waterproofing measures was revealed.
• The evaluation of structural integrity of circumferential joints with three levels was proposed.

To simulate the failure mechanism of tunnel segmental lining joints and longitudinal bolts under uneven longitudinal ground settlement, a numerical model with 3D lining rings and bolts was established. The loads were divided into two parts: the soil pressure around the tunnel just after construction and a displacement loading according to field measurements of uneven longitudinal ground settlement. The interactions between the lining tenons, bolts and their holes, were determined. The results indicated that the deformation of the circumferential joints consisted of opening and dislocation, but the dislocation was dominant. The progressive failure of bolts and waterproofing measures were also revealed. The evaluation of structural integrity of circumferential joint and the mitigate measures were proposed in order to ensure the operational safety of a metro tunnel.