PENTA-OCEAN CONSTRUCTION CO., LTD. We have been jointly developing a 'batch-type in-situ mixing method for calcia-improved soil' that enables surface layer improvement of submarine soil.
Based on the data obtained from the construction test (Fig. 1) in the actual sea area conducted from July to
Calcia-improved soil is made by mixing soft dredged soil (2) with a calcia-improving material (3) made from steelmaking slag to improve its physical and chemical properties. (Fig. 3). The dredged soil can be used effectively without being disposed of, because it has the characteristics of solidifying when it is strong and suppressing the impact (turbidity) on the marine environment during construction. In addition to being used as a landfill material, it can also be used as a construction material for shallow waters, tidal flats, seaweed beds, etc. for the restoration of marine environments, and is a material that contributes to the creation of a blue carbon ecosystem (4).
The current method is pre-mixing, which transports the calcia-improved soil prepared in advance in a barge (5) or soil tank to a designated construction area and throws it into the sea. In contrast, the newly developed batch-type in-situ mixing method uses a closed bucket (Fig. 4) attached to a special ship for the sand compaction pile method (6), which is an existing offshore ground improvement method. In this method, clay and calcia-improved soil are mixed in a bucket to improve the soft submarine surface layer with calcia-improved soil on the spot (in situ) (Fig. 5). Since the series of construction work is carried out near the seabed, the construction method was also evaluated in this review as having no adverse effects on the water quality of the surrounding sea area.
The development of this construction method has enabled the construction of submerged earth retaining embankments necessary for creating shallows and tidal flats (Fig. 6), construction of embankments to prevent the inflow of sediment into navigation routes (Fig. 7), and scouring around quays and breakwaters (7). ), it is possible to expand the use of calcia-improved soil for preventive measures. We will proceed with the commercialization of this construction method and promote the spread and expansion of calcia-improved soil.
We will continue to contribute to the realization of a sustainable society by focusing on the development of environmentally friendly products and construction methods.
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