Simulation of stresses around tunnels from measurements of convergence and Overcoring Method

Abstract: During the excavation of the tunnel Morro Alto in the federal highway BR-101/RS was encountered faults along the longitudinal axis of the tunnel. After stabilization of deformations, the final convergence was less than 10 mm in the section close to the fault zone. Even with the apparent stability of the massive, cracks appeared in sprayed concrete line. From further research, it was identified that the failure was near the inner wall of the excavation, on the pillar between the two tunnels. Based on measures of Overcoring and displacements measured, a numerical model has been constructed and calibrated. Back analysis was identified by the strain relationship between horizontal and vertical tension was 2.5. So, it was concluded that there would be a need for new interventions in the excavation support system, the fact that even with k0 greater than 1, no new developments would occur that could damage the structure.