Non-Linear Analysis of Precast Concrete Segment Joints under High Compressive Loads

When a precast concrete tunnel lining is loaded, the joints rotate as the lining deforms leading to varying contact lengths. This paper presents a numerical study on a precast concrete segment joint subjected to a high compressive loading, using nonlinear finite element analysis. The precast concrete segment joint was idealised as a two-dimensional (2D) prismatic block and subjected to a 6000kN compressive load. The varying contact lengths due to deformation of the linings and joint rotation under loading was represented as varying load widths in the idealised model. The Mohr Coulomb model was used to approximate the non-linear behaviour of concrete in tension and compression with an introduction of tension cut-off to the Mohr Coulomb model to represent the tensile capacity of concrete based on mean tensile strength. The transverse tensile bursting stresses in the idealised block was analysed for different load width ratios (a/d) and compressive strengths of concrete and presented as proportions of the uniformly distributed basic stress on the idealised block. The tensile bursting stress distributions for varying load widths and characteristics concrete strengths was developed into design charts for use by engineers in industries to eliminate the need for extensive finite element analysis and use of empirical relations. The area under the bursting stress distribution curve is the total bursting force and was found to decreases with increase in load width ratio.