Pipe Jacking Through A Rail Embankment

Pipe jacking through rail embankments inevitably causes ground movements during excavation and construction. Excessive ground movements can lead to embankment instability and rail track distortions which could result in train derailment. Therefore, ground and track movements must be closely monitored during construction in accordance with the respective rail authority standards and geotechnical assessment. This paper presents the project overview, construction method, prediction of ground movements associated with pipe jacking, track deformation design criteria and construction performance for the Gerringong Bypass Belinda Street Culvert where seven 1500mm diameter reinforced concrete pipes needed to be constructed beneath the existing South Coast Line railway embankment. Extensive instrumentation and real time monitoring were undertaken during construction to ensure safety of the rail operation. The measured ground movements were back analysed and the assumptions were calibrated for the prediction of future movements due to subsequent pipe jacking. A contingency plan was implemented to ensure that the settlement criteria and operational safety were met.