There is strong demand to improve the functions of existing infrastructure and use them effectively as possible. Requests include measures to handle increasing cargo volume and larger ships and vessels, diversification of airport functions, and countermeasures to deal with existing facilities which can no longer be used due to increased external forces and other reasons. In addition, regarding waste disposal sites at ports which accept industrial and non-industrial waste, there is social demand for the highly effective use of them. On the other hand, it has become difficult to secure disposal sites which accept soil dredged from water channels for shipping routes. Accordingly, it is necessary to prolong the life of soil disposal sites.

Therefore, we will develop the following: techniques to improve the functions of existing infrastructure and to renew and efficiently change the intended use of existing infrastructure; techniques to reduce or effectively utilize construction byproducts; and techniques to effectively utilize waste disposal sites at ports.

As there were no effective methods for checking the status of improved objects underground in 3D in cases where the risk of soil liquefaction is addressed by injecting chemical grout into grounds with ununiform fine contents, we started examining methods for evaluating the quality of improved soils through geophysical exploration, and studied their effectiveness with the aim of establishing a suitable construction work management method. If such a method can be established, it will be likely to enable more sophisticated quality management during and after each construction work project and also promote i-construction. To this end, we combined indoor tests, on-site experiments, and numerical simulations to study the relation between the physical characteristics of improved soils and the datum measured during the geophysical explorations.

We conducted scale model experiments to observe the plastic behavior of steel pipe piles and their bending behavior underground in order to obtain basic data for high definition of performance regulation of piers. In addition, we made a flowchart indicating the basic concept of design for improving sheet-pile-type mooring wharves.

To visualize the microstructural features of original underground soils on site, we developed and produced a compact X-ray CT scanner and a special drilling machine that could capture underground images in situ on site.

We conducted numerical analyses for typical cross sections to examine how increasing the height of a bank would alter deformation of its body, by changing conditons such as the height of raised dredged soil, distance between the temporary partition wall of raised bank and the sea wall, structural and mechanical properties of the temporary partition wall of the raised bank, countermeasures implemented on the seawall itself, etc. To achieve the aforementioned objective, we conducted a centrifugal test to verify simulation results and formulated a study method for raising a bank directly behind the seawall.