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Construction Site Simulation
Mega-projects, like digging large tunnels, are associated with constructions sites of almost incredible size and complexity. In order to cope with this complexity and to check the impact of different possible scenarios regarding the building progress, simulation models are applied. For instance, logistics and the required working power and raw materials can be evaluated.
The Koralm railway will connect the cities of Graz and Klagenfurt at the beginning of the next decade with a high speed railway line. Part of this route will go through the Koralm tunnel which will measure 32.9 kilometers. In 2010, the STRABAG company, with more than 76.000 employees one of the largest construction companies in Europe, was awarded the contract for building the central tunnel segment. Until 2018 two parallel, single track tunnel tubes will be constructed. In doing so, 8.5 million tons of excavation material will have been moved and about 1 million cubic meters of concrete will have been used. Since the access to the underground construction site is through a building shaft of 60 meters depth, a large variety of logistic problems have to be solved in this area. For this purpose, an AnyLogic simulation model which was developed by acp-IT in close cooperation with the Bau Prozess Management (BPM) of STRABAG is applied. Here is a detailed description of the construction site simulation.
The building shaft is the center of the tunnel construction site. It is connected via bidirectional conveyor belts to other buildings and facilities. The concrete segments for the inner shell of the tunnel (tubbings) are kept right next to the building shaft in two storage places. Above these storage places in each case a tubbing production, silos and a concrete plant are located. The material supply and removal mainly takes place by the use of trains.
Overview Koralm Tunnel Construction Site (Source: STRABAG, edited)
The complexity of the material flows necessary for servicing the construction site is highlighted in the next picture. Cement, gravel and steel are further processed after the train and truck delivery in the tubbing productions and concrete plants. Pea gravel and mortar in contrast are directly used within the tunnel. The excavation material from the tunnel is transported to the recycling plant or is temporarily stored at disposal sites. Unusable material has to be removed.
Material Flows for Servicing the Construction Site (Source: STRABAG, edited)
In order to be able to apply the simulation model as a planning tool during construction site operation, a realistic modeling of all material flows was needed. For this purpose, especially the train transport, the conveyor belts located on the construction site, the concrete plants, the tubbing productions, the silos, the recycling plant, the disposal sites as well as the underground construction site had to be considered. The progress below ground, which means the speed of the tunnel drilling, essentially determines how much excavation and raw material has to be removed and delivered, respectively. In order to be able to compare several scenarios without substantial effort, the expected speed below ground is described in an Excel file that can simply be imported into the simulation.
The highest level of the model hierarchy is depicted in the next diagram and important model elements as well as applied building blocks of the acp-IT InFrame Synapse Simulation Suite are highlighted. It can be recognized how the gravel and the recycled excavation material are transported to the concrete plants via conveyor belts. The cement which is also needed is kept in silos directly located at the concrete plants. The concrete is reinforced with steel in the downstream tubbing productions. The construction site below ground (or more precisely, the corresponding icon) is equipped with a larger number of import ports through which the different materials are passed down to the dedicated elements in the model hierarchy. The excavation material from the tunnel is removed through the output port of the tunnel element.
Top Level of the Model Hierarchy (Extract Snapshot AnyLogic, Edited)
The model execution outputs a comparison of the planned and the "actual" building progress, and several other statistics. For instance, the traffic processed over the rail network, the loading and the throughput of the conveyors and the utilization of the different disposal sites can be analyzed. The following snapshot of a model execution shows a situation in which all storages and silos are well filled. Two locomotives are currently in the construction zone.
Model Execution (Extract Snapshot AnyLogic)