Osamu Okamoto

Application of RTK-GPS to immersion of caisson

In the construction of a huge bridge, a caisson for a pier construction must be set very accurately at a predetermined position in the water. The authors applied real-time kinematic GPS (RTK-GPS) positioning to the immersion of a caisson in the construction of Ohshima Great Bridge. The caisson was transported and set in place with a floating crane. On the caisson were installed two GPS antenna in order to measure the position and the attitude. They were at the corners opposite to the operating crane vessel so as to minimize interference by the booms of the crane. The reference station was set on the land 370 m away from the site. The position and the attitude were displayed for the crane operator in the vessel.

Experiment on Mitigation Effects of On-Land Buildings Caused by Tsunami and Storm Surges

The reduction effect of buildings for tsunami and storm surge in coastal area was verified with a hydraulic model test in a flat water basin.Water forces among the buildings and water levels and velocities at their backside were measured modifying their allocation of buildings in order to identify the causes of reduction of water level and velocity of wave run-up in the test. It was confirmed that the reduction effect by the allocation of building is varied according to the effect of energy loss by eddies generated around the buildings and the most effective one was a plover allocation pattern.Comparing the maximum run-up distance with the numbers of a regular allocation pattern, the reduction effect was confirmed at two lines in solitary wave and one line in long period wave.

NUMERICAL SIMULATION BY THE GROUNDHEIGHT MODEL ABOUT MITIGATION OF DISASTER BY FACILITIES OF PORT AND HARBOUR

Disasters caused by coastal hazards such as tsunami and storm surge tend to exceed protection targets for structural design. Such disasters, whose frequency of occurrence is very low, cause severe damage. In case of considering countermeasure for preventing disasters, mitigation of disasters by facilities of port and harbor is important. Therefore, this paper describes the results of two-dimensional simulation by ground height model . This results suggest a possibility of mitigation of disasters by facilities of port and harbor.