2008 年 48 巻 6 号 p. 755-770
This paper presents a piezocone penetration test (CPTu) method for evaluating soil liquefaction potential covering a wider range of soil types than previous approaches and using simplified stress-based procedures. In the approach, the adjusted cyclic stress ratio is calculated with a recent formula created by Idriss and Boulanger, and the cyclic resistance ratio is determined as a function of both adjusted cone tip resistance (qt1N) and soil behavior type index (Ic). The new method is established through artificial neural network learning of documented cases. One unique feature of this method is the inclusion of excess porewater pressure ratio (Bq) in the formulation of Ic as per Jefferies and Davies. The proposed method is shown to be more applicable to a wider range of soils, including geomaterials that were previously considered “too clay-rich to liquefy.” The ability of this method to delineate liquefied cases from non-liquefied cases is clearly depicted with 3-D and 2-D graphs. Case studies of selected ground failure sites in Adapazari using the proposed method yield results that agree well with field observations in the 1999 Kocaeli earthquake.
