Immersed tube tunnel

This is a kind of undersea tunnels, that is constructed by placing several pieces of watertight structures prepared at other places transported, installed and connected altogether into the excavated ditch prepared at the sea bottom.


Phenomenon of soft saturated sandy ground showing behavior like liquid by remarkable drop down of the shearing strength of the ground caused by earthquake and seepage pressure. This phenomenon is triggered by floating of soil particles coming off the connection between them.


This is a pass way excavated vertically used for transportation and ventilation. Control facilities such as exhaust systems and control room of the Niigata Minato tunnel are encased in the shaft.

Cement Deep Mixing processed ground

The ground improved by the Cement Deep Mixture method. This Cement Deep Mixture method is the work method to create rigid pillar shaped, block shaped or wall shaped stable processed soil ground reaching to deep ground layer of the same location by supplying massive, powder shaped or slurry conditioned caustic lime or cement to underground to mix forcedly with soft soil at the same site.

Finite element analysis of Liquefaction Program

This is the liquefaction analysis program based on effective stress analysis developed and opened by the public of Ministry of Transport Institute for Technical Research of Ports and Harbors (Current executive agency Harbor Airport Technical Research Institute).

Excessive pore water pressure

Pore water pressure is the pressure of underground water filled at the space between soil particles and the pressure deduction static water pressure from Pore water pressure is called as Excessive pore water pressure. Underground pore water pressure increases when the soil filled with water is pressurised.


Gasket is thin watertight sealing staff to be placed between connections such as pipes and flanges.


The gal is a unit of acceleration, which is defined as 1 Gal=1cm/sec2.