Takehiro Tsuchida
Study on the Validity of Drainage Methods in the Liquefaction Countermeasure Constructions of Sandy Soils
Satoru Ohtsuka
Liquefactions have been ccaused by a number of earthquakes. In the past, they were been confirmed in the Kobe earthquake and the Niigata Chuetsu-Oki earthquake. In the Great East Japan Earthquake they occurred in recent years, ground deformations due to liquefactions in artificial grounds and coastal areas are well known. Knowledge of liquefactions are widely used in civil engineering and construction. Moreover, a number of liquefaction countermeasure construction methods have been devised. However, liquefaction countermeasure constructions which were utilized in damede reduction have remained in a very limited fields, such as large-scale public works and large-scale buildings. In particular, small buildings that individuals owned are hardly executed liquefaction countermeasure construction methods, hence they are damaged by the ground deformation due to liquefaction during earthquakes. Therefore, there is "the drainage pipe construction method" as the method of construction that can be executed at low cost in narrow space.
This study was performed model experiments focusing on the drainage pipe for the establishment of the design method. Furthermore, the estimated formula for drainage distance was proposed from these results, the validity of the formula was confirmed by comparing model experiments and full-scale experiments. Specifically,ĦĦit was verified in terms of the difference between the inside diameter of pipes, the aperture ratio of side of pipes, and the incidence of liquefaction by depth. Then, it was found each of correction factors. By using correction factors, it was shown the relationship between the drainage distance and excess pore water pressure ratio of the drainage pipe in two equations of logarithmic model and bilinear model. Therefore, the estimated formula was confirmed to be effective.
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