Developed by Ruhr-Universität Bochum and SimPlan AG.
Problem Definition
Construction of a tunnel with a tunnel boring machine (TBM) is usually a long-lasting project with complex interdependent processes and a comprehensive supply chain. Monetary losses due to equipment breakdowns and insufficient supply chains can range around 20% of the whole project cost, and that often means millions of dollars. The cost of one hour of down time is very high and project managers have to do their best to avoid unnecessary delays. The aim of the simulation project, which was carried out at Ruhr University Bochum in Germany, was to create a simulation model that would be capable of determining the bottlenecks in the established processes in order to minimize the possible monetary losses.
Solution
Construction of a tunnel with a TBM is determined by the process-related excavation of soil and the construction of the tunnel itself. Furthermore, a steady flow of excavated soil must be propagated through the machine. However, the construction process is often disturbed for many reasons and then the processes must be suspended or delayed.
Since AnyLogic software makes it possible to combine several simulation techniques, the modelers were able to reflect all the peculiarities of the system by simulating the process-related works with the help of state-charts (Discrete Event Modeling), and the continuous propagation of soil with System Dynamics. The System Dynamics method was also used to memorize the current status of the excavation in case of a disturbance. The multimethod approach also enabled the modelers to easily simulate disturbances of certain machine components.
The assembly elements of the TBM were modeled separately in Active Object Classes in order to provide a flexible and reusable simulation model.
Besides the TBM, other works were simulated (back up system, tunnel works, on-ground construction site, and external supply chain) which allowed the model to be completely aligned with real-life and its uncertainties.
Outcome
The developed simulation model can illustrate and quantify the impact of disturbances on the progression of a specific tunneling project. The simulation of on-site processes and external logistics will also allow a project manager to reduce weak spots and plan required back-up stock. The minimization of unnecessary standstills and performance losses will shorten the duration of a tunneling project and optimize its budget.
See the video of Tobias Rahm from Ruhr University Bochum presenting this project at The AnyLogic Conference 2012 or download his presentation.
