Change of Waterline and Water Depth at Izmit Bay Due to 1999 Kocaeli Earthquake in Turkey

The 1999 Kocaeli Earthquake of August 17,1999 hit the western part of Turkey causing very great damages. From a result of our investigation and survey, typical geotechnical damages on this earthquake were pointed up except structural damage due to inertia force. One was a settlement andfor tilting of buildings induced by the ground deformation such as soil liquefaction or bearing failure in Adapazari City. Another was a widespread land loss in the south of coast in Izmit Bay, induced by the fault movement. In this paper we deal with the widespread land loss around Izmit Bay. The authors check into the relationship between the submerged area and the rupture of the fault, and then carried out the measurement of water depth at several cross sections of offshore in Izmit Bay. In order to clarify the aspect of loss of the coastal land, the topography of the seabed before and after the earthquake were compared. And then, some in-situ tests were conducted near the submerged area. From the result of the measurements, in-situ tests and the field survey, the causes of the loss of coastal land could be anticipated

Evaluation of Liquefaction Potential of Gravelly Soil Layer Based on Field Performance Data

In general, gravelly soil layers are considered to be less susceptible to liquefy during earthquakes than sandy soil layers. However, in 1995 Hyogoken-Nambu Earthquake, sand ejection due to liquefaction was observed in Port Island and Rokkco Island, which were man-made islands reclaimed by gravelly soils. In this paper, firstly, site investigation including sampling by freezing technique was conducted in Rokko Island where lots of ejected sand was not observed during the earthquake to know liquefaction strengths of the reclaimed deposits. Secondly, earthquake response analyses were conducted for a site in Rokko Island as well as a site in Port Island to evaluate maximum stress ratios which were generated in the reclaimed deposits during the earthquake. Finally, relationships between maximum shear stress ratios during earthquakes and penetration resistance were investigated for liquefied sites and nonliquefied sites in the man-made islands

Numerical Simulation of Shaking Table Test by Nonlinear Response Analysis Method

In this paper we described the results or numerical simulation or shaking table test on two dimensional soil-structure interation system to verify an application or newly developed nonlinear response analysis method. This code was a so-called U-W analysis method based on the deformation theory or saturated porous material proposed by Biot and constitutive relations to simulate the nonlinear characteristics or soils were induced by the elasto-plastic theory. Input material constants or soil were decided by referring the data or popular soil element test. Because the properties or soil were heavily dependent on confining pressure, then static and dynamic soil tests were carried out under an equal low pressure to the shaking table test. The results or numerical simulation by using the material constants obtained from soil element tests were in good agreement with those or shaking table test and the applicability or our analysis method to dynamic problems was verified with the considerable confirmation