Project title: Wireless Sensor Network Monitoring and Modelling of Dublin Tunnel
Researcher: Chao Wang
Research purposes and aims: It is widely observed that civil infrastructures inevitably deteriorate with time. After being in service for more than a decade, Dublin Port Tunnel is found to show some structural and hydraulic deterioration and deformation, which might pose a threat to tunnel serviceability and even safety if lack of a long-term monitoring scheme to evaluate the condition of these deteriorations on a regular basis. Therefore, in this research project, it is aimed to assess and evaluate the structural health condition of Dublin Port Tunnel using an innovative monitoring technology and numerical simulation. The monitoring method to be used is wireless sensor network which features wireless data transmission and low cost due to elimination of costly cablings. It is expected that the deformation mode and deterioration propagation of Dublin Port Tunnel can be revealed by adopting this long-term monitoring approach. Besides, it is hoped that the application of this WSN method can provide some guidance on future civil infrastructures, wherever during construction or maintenance stage. Apart from the monitoring, a series of finite element analyses also would be conducted to first help validate the monitoring results, and also eventually to assess and evaluate the structural health conditions of this tunnel in the long term.
Research hypotheses: Even decades after construction, tunnel structure still deforms with time subject to concrete deterioration, time-varying ground condition and etc. The long-term tunnel deformation at some critical locations can be monitored by a wireless sensor network over a number of years, and the gathered field measurements will be able to depict the tunnel deformation mode in a quantitative manner. Furthermore, the field measurements can be used to validate an advanced finite element tunnel model, aiming to reveal ground-tunnel interaction comprehensively and predict the time-dependent tunnel behaviour for the next decades. In terms of the hypotheses adopted in this project, some assumptions may be made for implementing numerical simulations, including: 1) no displacements were allowed at bottom boundary, top boundary was set to be free, and the other four vertical sides were fixed in displacement that is perpendicular to their side faces; 2) the initial pore water pressure distribution profile was considered to be hydrostatic; 3) detailed excavation procedures were simplified as several main steps with the emphasis on long-term behaviour of this tunnel; (4) deterioration of the tunnel is modelled by linear variation in hydraulic properties.