Study on the Damage Due To Sloshing of Liquefied Ground in Chiba City During the Great East Japan Earthquake

Abstract eng:
The Great East Japan Earthquake on March 11, 2011 caused severe damage, particularly to the strip of land along the Pacific Ocean from the Tohoku Region to the Kanto Region. In the Tokyo Bay Area, widespread liquefaction destroyed a large number of wooden houses, pushed up road pavements, and damaged water and gas pipes and manholes. The liquefied ground shook repeatedly and the duration of shaking was long—the Great East Japan Earthquake lasted 3–4 minutes. After the earthquake, a field survey was conducted, targeting the liquefied areas at landfill land with low soil strength such as the landfill of the Tokyo Bay area to correlate ground motion intensity and damage severity. Liquefaction at the bottom layers occurred in inclined or irregular ground surfaces and buckling are common near this boundary. To investigate the mechanism of sloshing, twodimensional seismic response analysis was conducted for areas where damage has occurred in Chiba using FLUSH, a two-dimensional FEM analysis. The shear modulus was reduced to 1/50, 1/100, and 1/200 of typical values. Consequently, the large compressive and tensile strains in the horizontal direction at shallow depth near the road buckling were reproduced at low G values, i.e., 1/100 and 1/200 of typical values. Large compressive and horizontal strain were observed near the boundaries of areas that were not affected by liquefaction within the liquefaction-affected area. Because of the long duration of ground shaking, the nonliquefied and liquefied layers repeatedly collide; consequently, large strains in the horizontal direction occurred.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket