ABSTRACT
The limited availability of space at the surface makes the need for underground space for the public and private use increasingly evident. Notwithstanding the need, in particular in urban environments, onerous criteria are enforced on the development of underground schemes. The increasing demand for underground space in the past decades initiated the development of tunnel mining techniques that allow the construction of large underground openings in soft ground with only limited surface disruption. During the development of the design for large tunnels, the whole range of engineering skills from the appreciation of the ground conditions to the knowledge of, and familiarity with state of the art materials and technologies in tunneling has to be employed. Codes and requirements imposed by tenants, utility owners, environmental concerns and public safety add to the limitations before the designer commences with the development of a constructable scheme within this tight fence of criteria. The development of new techniques or novel combinations of known methods is often triggered by such stringent conditions.
