Construction methods developed for "Diver Street™", next generation road concept
Construction of underground space using steel sheet piles to reduce costs and construction period
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Technologies
Obayashi Corporation, in collaboration with Toyota Frontier Research Center, and Toyota Central R&D Labs, Inc. have created the next- generation road concept, Diver Street. In addition, we have developed a new method for constructing underground space, which is necessary to realize this concept.
Diver Street has underground space, which can contribute to the advancement of logistics systems and efficient infrastructure layout, such as eliminating roadside utility poles and ditches. It can also be used for BCP measures such as rainwater storage during heavy rain. In addition, the highly functional road surface can contribute to the integration of next-generation mobility by enabling road-to-vehicle communication for automatic driving and power supply while driving.
The construction method developed for the Diver Street can create underground spaces in a short period of time and at low cost. By utilizing digital mockups and applying civil engineering design technologies, structural analysis during vehicle travel and vibration/noise analysis were conducted to confirm the effectiveness and feasibility of the underground space construction.
Underground space is used for distribution by Automated Guided Vehicles
In the conventional method, the underground space is constructed with precast box culverts (PCa box culverts). First, temporary steel sheet piles are installed for underground space work. Next, the factory-made PCa box culverts are transported to the construction site by trailer and installed by a large crane. Then, PCa box culverts are connected and the temporary steel sheet piles are pulled out after backfilling the sides of box culverts. For this series of work, a distance of at least 1.5 meters from surrounding buildings, roads, and other site boundaries had to be secured as the construction area, making the construction period and cost an issue.
The newly developed method eliminates the need to pull out temporary steel sheet piles by using steel sheet piles in the main construction. Therefore, only factory-made precast slabs are needed to be installed, enabling cost reduction, shortening of construction period, and reduction of excavation area.
The features of the developed method are as follows
Reduction of construction costs
Works pulling out steel sheet piles and framing side walls are no longer required. In addition, since only the deck slabs are precast components manufactured at the factory, the manufacturing and transportation costs for these components are greatly reduced. As a result, construction costs can be reduced by approximately 40% compared to conventional construction methods.
Shortening of construction periods
The process of pulling out steel sheet piles and building side walls is eliminated. In addition, since only the floor slabs are precast, assembly of each precast part such as the upper and lower parts is not required, significantly reducing the amount of work. As a result, the construction period can be shortened by approximately 20% compared to conventional methods.
Reduction of excavation area
The excavation area can be reduced by eliminating the need for workspace between temporary steel sheet piles and the side walls of the structure. Steel sheet piles can be placed at the boundary of the site, even in close proximity to buildings.
Load supported by steel sheet piles
Steel sheet piles are used as support structures in addition to their conventional earth retaining function. By employing precast deck slabs and other lightweight road surface structures, vertical and horizontal loads transmitted from the road surface are supported by the sidewall friction force (*1) of the steel sheet pile and other factors.
Toward the realization of "Diver Street," Obayashi will conduct research and development of high performance road surface functions that can be updated as the city and roads evolve, and will also promote research on how roads should integrate mobility and infrastructure. In addition, by developing and providing new road construction methods that take into account economic efficiency, such as shortened construction periods and reduced costs, we will contribute to the construction of the infrastructure for future smart cities.
- *1 Sidewall friction force
Upward resistance force when the contact surfaces of the ground and the steel sheet pile rub against the load acting downward on the steel sheet pile