Simplified approach to the design of segmental tunnel linings

A new simplified approach to the hyperstatic reaction method (HRM) for the analysis of segmental tunnel linings is introduced. The influence of segmental joints on the lining behaviour is taken into account by considering opening/rotation of the joints under external loads, which cause a reduction in the contact surface area between two segments at the joint location and certain surrounding zones. Consequently, a decrease in the inertial modulus and cross-sectional area at these sections of the lining ring is expected. A specific implementation was developed using a finite-element method framework in which an iterative procedure was applied with the height of the joint section as the unknown parameter. The results obtained using the new simplified HRM (SHRM) were compared with those obtained using the existing complex HRM, which takes joints directly into account, and a three-dimensional numerical model. The results obtained show that the SHRM can be used to estimate the behaviour of a segmental tunnel lining effectively.