Mechanics mechanism of slab-type short bolt composite structure for repairing cracked lining under compression shear

Abstract

In order to repair the tunnel linings with compression-shear cracks under small eccentric compression, the use of slab-type short bolt composite structure to repair tunnel cracks is proposed in this paper through the method of model test and numerical simulation. From the perspective of the component, the mechanics mechanism of repairing the lining with shear cracks in the slab-type short bolt composite structure is studied. The model tests for repairing small eccentric compressive components with the slab-type short bolt composite structure were designed and carried out, and the ultimate bearing capacity and load-strain curves of the components were obtained, which were matched in the numerical simulation. The form of the slab-type short bolt composite structure is determined, and the model is established by using ABAQUS finite element software to study the design parameters. The influence laws and recommended values of three design parameters, namely, the thickness of repairing steel plate, the strength grade of the short bolt, and the bolted depth of short bolt, on the ultimate bearing capacity of components are obtained. The issue of repair timing during the field application of slab-type short bolt composite structure is studied, and the difference in component load-deformation curve between “pre-peak repair” and “post-peak repair” of the composite structure is clarified to give the suggested latest repair time.