Abstract

This presentation will discuss how a number of monitoring instruments were installed within two sections of an existing grey cast iron segmental tunnel lining (the Post Office Tunnel) before the works of Crossrail and London Underground pass beneath, in a parallel and perpendicular configuration respectively. The monitoring instruments were made up of displacement transducers, vibrating wire strain gauges and distributed optical fibre strain sensing. Results from these sensors have started to shed new light on the response of these existing cast iron structures to ground movement.

Now using this observed data to calibrate the boundary conditions in a detailed structural FE model, the method of developing the model, with empirically calculated imposed ground movement will be presented, and from this, the mechanisms of the tunnel lining displacements under these conditions can be interrogated; with the overall goal of better understanding the structural performance, and improving the methods by which these assets are routinely assessed.