Investigating the mechanical performance of contact point in bolted segments by laboratory tests

Abstract

As normal and tangential stiffness of contact points in segmental linings remarkably depends on normal stress in contact locations and this issue has not been investigated in the previous studies on bolted connections, the present study tried to develop a precise contact model based on experimental direct shear test results. By selecting the normal stress between 0.25 and 2 MPa, about 70 tests were performed on the grooved cubic samples of contact points of segments with and without bolt. As practical outcome of this study, the contact shear and normal reaction moduli k_s and k_n were related to contact normal stress via two linear regression equations considering R² of 99%. To estimate the applicability range of the proposed relations, finite element models of an urban tunnel liner were developed using the concept of beam on elastic foundation considering the proposed contact model of the present study. Finally to access the sliding and bolt acting conditions of contact points, some sensitive analyses were conducted.

Keywords:

• mechanised tunnelling
• segmental lining
• longitudinal joints
• bolted connections
• direct shear test (DST)
• reaction modulus

Disclosure statement

No potential conflict of interest was reported by the authors.