Ground Behavior during Earthquake and its effect on Foundation Piles

The violent ground shaking during the Hyogoken-Nambu earthquake caused landfills in the port area to liquefy leading to widespread occurrence of ground deformation including settlement and lateral spreading. As a result of the ground distortion, various types of damage were incurred by infrastructure such as lateral shifting of quay walls, breakage of gas and water mains. The landfills in the several affected areas were first reclaimed around 1953 by transporting soil from borrow areas at the foothill of the Rokko Mountains. Large amount of the soils was transported by a long-distance belt conveyer system to the sites of reclamation along the old shoreline. Several islands north of Rokko Island were constructed during this period. The second phase of land reclamation began in 1968 to construct two large man-made islands further offshore to the south. Port Island with an area of 436 hectare was constructed during the period from 1966 to 1980 by transporting soils from Suma which were carried in bottom dump-barges and placed under water at the site of reclamation. The 580 hectare Rokko Island was constructed between 1972 and 1990 by excavating soil materials from Suma and also from other sites in the Rokko Mountains. The grain size distribution of the materials used for the reclamation of Port and Rokko Islands are shown in Fig. 1.1 Fig. 1.1 Grain size distribution of the materials used for land reclamation: Two panel graphs compare particle size distribution for land reclamation materials. The left graph represents data from the ship oil supply site in Port Island. The right graph represents data from Rokko Island. Both graphs plot particle size in millimetres on the x-axis and % finer by weight on the y-axis. Each graph shows a solid line with dotted lines indicating variability or uncertainty. The particle size ranges from 0.001 millimetres to 100 millimetres. The percent finer by weight ranges from 0 to 100 %. The graphs illustrate how the grain size distribution differs between the two locations. https://www.w3.org/1999/xlink" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003762058/d377c2d5-2b9c-462f-ab5f-fe435ea190fc/content/pg16_1.tif "/> (a) Ship oil supply site in Port Island; (b) Rokko Island