Estimation of tunnelling induced ground movements in soft ground – Part 1: Methodology

Accurately estimating tunnelling-induced deformation is important in assessing the effects of tunnelling on nearby structures and facilities. The consequences of inaccurate estimates can also be costly. Any method that provides greater accuracy in the assessment of tunnelling-induced ground movements, thereby providing a design tool to mitigate potential risk to third party property, has the potential to reduce the number of unwarranted incidents and insurance claims. At present, there are no well-accepted methods available to tunnel designers to calculate tunnelling induced ground loss values and ground deformations from the first principles. Instead, designers are required to rely on empirical assumptions derived from past experience and the outcomes of similar projects. However, as no two tunnelling projects are the same, the complexity and risk estimations and the consequences of failure seem to increase with every new project. This paper describes a methodology to assess ground loss values and closed-form formulae for the prediction of tunnelling-induced ground movements.