Effects of tunnelling on a single pile: Three-dimensional design tool

In most tunnelling projects in urban areas, a preliminary assessment is often required of the impact of a tunnel excavation on foundations adjacent to the tunnel. Despite the significant recent advances in computer hardware and commercial software, a full 3-D analysis is still relatively costly, especially if it is to be employed as a preliminary assessment tool to ascertain the impact of tunnel excavation on existing foundations. This paper provides a convenient and cost-effective design tool, in the form of design charts, that will allow an economical preliminary assessment of the 3-D effects of tunnelling on a single pile. The method adopted to develop these design charts will be briefly described and their use in practice will be illustrated by application of the design charts to several published case histories.