A project Alan Auld Engineering (AAE) have been involved with since 2005, is a 1.1km tunnel owned by Sembcorp Utilities Ltd. running under the River Tees. The 3m, steel segmental tunnel is used to transport various chemicals such as feed stocks, gas, fuel oils, and brine between a chemical plant located on either side of the River Tees.
As a consequence of dredging operations carried out to deepen the navigable shipping channel in the river, an imbalanced load was placed on the tunnel walls resulting in distortion and cracking in the lining plates. In 2005, AAE carried out an initial visual inspection of the cast iron tunnel lining which identified significant movement. In order to ascertain the full extent of movement and distortion, further detailed surveying was completed over the following years to establish a pattern of movement. In conjunction with the surveying a suite of real time remote monitoring equipment was proposed by AAE.
AAE arranged the installation of the monitoring instrumentation which included crack gauges, strain gauges and tilt-meters to monitor on-going movement in the tunnel. The monitoring data was communicated to a data logger with facilities to monitor the live data and trend information via a web browser. AAE further completed structural design analysis, design drawing and detailing of additional steel support hoops which have since been installed as a means to possibly extend the life of the tunnel.