BIM (Building information modeling) is used in the construction of 3D model to adjust the 3D positions of the material and is being utilized as a database for design, construction planning and maintenance by recording the construction procedure and member specifications. Initially it was mainly applied for the construction of building structures. In recent times the wide application of BIM to civil engineering structures has begun to get progressed for utilizing in general infrastructures such as roads, bridges and tunnels. However BIM has not been applied to port facilities in Japan yet. This report presents the result of applying BIM in the construction work of liquefied natural gas (LNG) receiving pier.
Pier construction site is located in the northeastern part of Japan, at Soma port in Fukushima prefecture. In order to overcome the energy depletion immediately after the Great East Japan earthquake 2011, it was necessary to secure diverse energy sources. In order to advance the import of liquefied natural gas, a petroleum resource company has proceeded with the construction of mooring pier for the LNG import terminal in last 2 years. During initial stage of construction, there were few concerns such as, the abundant rise and fall in bearing layer under the seabed that drives the foundation pier, the facilities making up the pier were close to each other and the equipment installation of the platform was complicated.
In this pier construction, we aimed at achieving the following three points by applying BIM.
1. To predict and ensure whether the pile foundation certainly attains the bearing layer.
2. To confirm that the structures do not interfere with each other before construction and to explain the workaround to the workers in advance.
3. To calculate the vessel position where the pier could be constructed safely and to decide appropriate anchor placement position in advance.
By applying BIM in this construction work, we achieved the objectives by overcoming the problems by the following procedures.
1. At first the depth of the bearing layer is represented by the 3D model from the boring data. During driving a pile, the electric resistance value of the piling installation is then measured and the elevation of the bearing layer of the 3D data is corrected sequentially. As a result of repeating measurement and correction of 3D data as well as completely ascertaining the correct bearing layer height, we realized the necessary embedded depth that is required for all piles.
2. By inserting a jacket model into the reproduced pile shaped model in BIM, we confirmed that there was no conflicts between jacket and pile. In addition a surveillance camera was installed inside jacket sheath pipe to properly guide the jacket to the pile position.
A drone equipped with the digital camera flew and captured the shape of the wave dissipating concrete blocks under the bridge position. By superimposing the model of the bridge on this, we confirmed that these two do not interfere.
The reinforcing bars of the slab concrete of the platform of the pier were reproduced on the model and the embedded metal fittings of the equipment were superimposed on this and confirmed that both did not interfere. In case of interfering, we moved the rebar before attaching the anchor. Showing these work procedures in a 3D model enabled the workers to have a deep understanding of the construction procedures.
3. According to the work process, the vessel position during construction is reproduced on the model and the anchor position was reproduced at the same time. We confirmed that the crane ship can enter the installation position by hanging the jacket while the anchor of the work vessel can be placed in the required position beforehand. An illustration of the procedure was used to explain to the vessel operator. By applying advanced technology, the construction was implemented safely and smoothly through the procedure.
As described above, the construction site using BIM equipped with a built-in monitoring camera, equipment to measure the electric resistance of the pile and aerial photography for shape confirmation, was concurrently carried out. As a result, the construction was ensured to complete with high accuracy. In addition, the complex operation can be easily understood by the 3D model combining the BIM model and the field verification results. Thus, it is very effective in giving work instructions to the operator.
On the other hand, it is also a fact that the data input into BIM needs time and experience. In case of civil engineering work, it is necessary to combine the construction ground data and the surrounding landscape data with the structure model. Therefore, the number of programs to be handled becomes large which leads to the time requirement to learn the program operation. Moreover since the number of operator expertise in BIM operations are still few in the country, it is mandatory to train within the company for the time-being. While consensus on the application of BIM is progressing within the construction industry, the secured human resource is an urgent issue.