Tunnelling-induced settlement damage to masonry structures: Centrifuge testing and computational modelling

In the United Kingdom, and throughout the world, tunnelling in urban environments is essential to provide necessary infrastructure. Further, major infrastructure projects, many of which will require tunnelling, will be likely to increase with continued urbanization. However, tunnelling can place buildings at risk. Therefore, reliable assessment tools to predict tunnelling-induced damage are essential to determine whether protective measures are necessary. Useful models exist for predicting tunnelling-induced damage, but these methods need refinement, making use of new and existing data and increasing computational resources.

The primary aim of this proposal is to obtain the necessary experimental data to improve analytical and computational methods of predicting tunnelling-induced settlement damage. Specifically, this will be achieved through three primary steps. First, centrifuge testing, in which small scale models can be used to investigate full scale structures, will be used to evaluate the interaction of the soil and the structure during the tunnelling process. In particular, realistic scale models will be 3D printed and the tunnelling process directly simulated. Second, these physical tests will be simulated computationally, to evaluate and improve computational methods. Third, additional simulations will allow extension of experimental results to a wide range of tunnelling scenarios.

The experimental and computational results will be directly used to create improved analytical and computational guidelines for predicting tunnelling-induced settlement damage. These guidelines will be evaluated with respect to existing field data. It is envisioned that these results will have an immediate impact on the tunnelling industry in the UK and around the world.

Global plans for infrastructure expansion are substantial, and will play a significant role in the global economic recovery. Due to urbanization, tunnelling will play a vital role in infrastructure development. Tunnelling in urban areas poses a significant risk to existing infrastructure, particularly older buildings. Tunnelling-induced damage has huge economic implications, both in direct damage repair and related insurance premiums.

Thus, better methods of predicting damage could have a significant impact by reducing costs and litigation related to tunnelling-induced damage, and by informing appropriate damage prevention measures. Specifically, the engineering community would benefit from procedures which can be used to better predict damage. Further, contractors, insurers, and property owners would benefit from improved certainty related to the effect of tunnelling on nearby buildings. There are also significant societal benefits in having better defined methodologies for prediction and prevention of building damage due to tunnelling projects. Public confidence in the engineering assessment of potential building damage is important, and must not be neglected.

These benefits are directly relevant to the UK, where underground infrastructure is expanding. This is evident in the Crossrail project (to be completed by 2018), for which 21 km of twin bored tunnels are planned under central London. Similarly, for the Thames Tunnel project, 25 km of bored tunnel is also proposed along the Thames River. Furthermore, the planned HS2 high speed rail project, and expected high speed rail expansion in coming years, will continue demand for tunnelling and excavation in urban areas. Therefore, the need to better predict the building damage which may be caused by these (and future) major construction projects is paramount.

In addition, international expansion of infrastructure will affect the UK economically. UK companies have an established expertise in tunnelling and excavation work, which is continually being sought by rapidly expanding countries in Eastern Asia and around the world. Globally, current and future tunnelling projects total an estimated $220 billion of work, through which the tunnelling industry will play a significant part in global economic recovery. It is crucial that this UK expertise is not just maintained, but continually expanded.

Significant past research has been conducted in this field, providing a solid foundation on which to interpret new results. Thus, unlike many research studies, impacts on industry practice are foreseen in a relatively short timescale.

In summary, this work would have an immediate impact for planned construction projects in the UK, but also for expected future infrastructure expansion in the UK and around the world.