Assessing ground interaction effects and potential damage on existing tunnels before and after new excavation works
The research project sought primarily to investigate the effect of tunnelling on existing tunnels with a focus on the behaviour of grey cast iron segmental linings. This was achieved through field measurements, laboratory testing and numerical analysis.
Extensive field instrumentation was installed within the Central Line tunnels and the ground in their vicinity where the new 7.1-m diameter Crossrail tunnels passed beneath them. In the structures laboratory various tests were performed on half-scale segments and a ring using load and displacement control to assess stress and bending moment distributions within the lining as it was distorted to shapes observed in the ground. Numerous numerical analyses were performed of both the structural testing and the field conditions using ICFEP with its state of the art constitutive models and boundary conditions. Advanced laboratory testing of high quality samples of London Clay taken during installation of the field instrumentation (at Hyde Park) provided refined soil parameters for the numerical analysis.
The work has provided great insight into the behaviour of existing grey cast iron segmentally lined tunnels under field and controlled laboratory displacement fields.
More information can be found by reference to some of the publications that have emerged from the project:
Fearnhead N., Maniscalco K., Standing J.R. and Wan M.S.P. (2014). Deep excavations: monitoring mechanisms of ground displacement. Proc. ICE - Geotechnical Engineering, Vol. 167, GE 2, pp 117-129. (Link to paper)
Wan M. S. P. and Standing J. R. (2014). Lessons learnt from installation of field instrumentation to monitor ground response to tunnelling. Proc. ICE - Geotechnical Engineering, Vol. 167, No. GE5, pp 491 – 506. (Link to paper)
Wan M. S. P. and Standing J. R. (2014). Field measurement by fully grouted vibrating wire piezometers Proc. ICE - Geotechnical Engineering, (http//dx.doi.org/10.1680/geng.13.00153). (Link to paper)
Yu J., Standing J.R., Vollum R., Potts D. M. and Burland J.B. (2014). Stress and strain monitoring at Tottenham Court Road Station, London, UK. Proc. ICE – Structures and Buildings, (http//dx.doi.org/10.1680/stub.14.00012). (Link to paper)
Hauswirth D., Puzrin A. M., Carrera A., Standing J.R. and Wan M.S.P. (2014). Application of fibre optic sensors for simple assessment of ground surface displacements during tunnelling. Géotechnique, (Accepted for publication July, 2014).
J. Yu. (2014) Assessing ground interaction effects and potential damage on existing tunnels before and after new excavation works PhD Thesis, (Jessica Yu PhD Abstract).
EPSRC (Grant No. EP/G063486/1) and Crossrail with collaboration from Morgan Sindall and LUL.
Jessica Yu, Michael Wan, Vasilis Avgerinos, Katerina Tsiampousi, Ramtin Hosseini, Sheida Afshan,Khalid Al Haj