Stability of underground tunnelling using relaxation techniques

Abstract

This project involves the investigation, development and verification of two numerical models aimed at predicting the settlement profiles caused by the process of underground tunnelling in soft cohesion less soils using the computer program Fast Lagrangian Analysis of Continua (FLAC). The numerical models created will investigate the settlement profiles caused by the tunnelling process from a transverse and longitudinal cross sectional view using a relaxation process employed in FLAC. Any major problems that arose during the model development will be analysed, discussed any the possible remedies will either be discussed for future work or applied where possible. The basic approach of this project was to research the two situations under investigation, develop the appropriate models in FLAC, verify these models though comparison with reputable published paper and analyse the results from a series of parametric studies. The main focus of the investigation was to develop new models for the two problems utilising a relaxation technique employed in FLAC. Few problems were encountered in the development of these models – mainly from the ability of FLAC to accurately model cohesion less soil structures. The completion of this project has adequately demonstrated that FLAC is able to be utilized to develop models for the two different tunnel heading profiles. However, it was recognised that the circular tunnel heading was model would require further development to accurately model cohesion less soil structures.