Effectiveness and limitations of the existing modelling in application for thermohydromechanical evolution of clay bulkhead in tunnel

The Tunnel Sealing Experiment (TSX) was an international project developed by Japan, France, the United States of America and Canada. The TSX consisted of an 11.45-m-long sand-filled chamber between two bulkheads. At one end, a clay bulkhead was constructed of 9000 clay-sand blocks (each being 360 mm × 105 mm × 170 mm in dimension) and at the other end a 76 m3 concrete bulkhead was constructed using low-heat, high-performance concrete. The experiment was operated in two distinct phases. The first phase was the stepwise pressurization of the chamber to 4 MPa in order to investigate the ability of the two bulkheads to resist hydraulic flow. The second phase involved circulating heated water through the chamber raising the temperature of the sealing system in order to evaluate the influence of elevated temperature on the performance of the bulkheads. This paper focuses on discussing effectiveness and limitation of the existing numerical modelling in application for thermohydromechanical evolution of clay-based materials based on the comparison of measurements with numerical results of the hydromechanical evolution of the clay bulkhead under ambient conditions as well as during pressurization of the chamber and the coupled thermohydromechanical evolution of the clay bulkhead during heating. These numerical results were obtained from using the numerical modelling tools (MOTIF, COMPASS, CODE_BRIGHT and CLEO).