Department of experimental system for soil-water-structure coupled models by using a drum centrifuge

本研究的主要目标是开发一套滚筒离心机中波浪现象的模拟系统，使我们能够对土-水-结构系统的耦合现象进行物理模拟。设计了一个安装在现有直径为0.8m的转鼓离心机中的系统。考虑到合理的相似性，所设计的变速电机驱动的波形发生器的冲程为15 mm，频率为5.7赫兹。系统上还安装了一台CCD摄像机，用于可视化跟踪离心场作用下的波的作用。实验证明，该系统在高达100G的离心力作用下运行良好。研究发现，桨叶的形状对所产生的波浪特性有很大的影响，为了找到最佳的桨叶形状，制作了四个桨叶并对其进行了试验。进行了一系列生产性试验，观察了波浪作用下砂层中孔压的响应，结果表明，在波浪作用下，砂层中产生了高达1.2kPa超孔隙水压力，导致了液化现象。本文所建立的试验系统可用于检验在波浪作用下建造在砂土层中或其上的结构物的稳定性。这项研究的成果将出现在两篇论文中，一篇是将在里约热内卢举行的《土力学和路面力学的最新进展》中的《小型离心机的发展和几个初步试验》，另一篇是日本中部地区土力学和基础工程国内会议。

The main target in this research is to develop a system for simulating a wave phenomenon in a drum centrifuge, which enables us to perform physical modeling of coupled phenomena of soil-water-structure systems. A system was designed to be housed in the existing drum centrifuge of 0.8m in diameter. By consideration of proper similitude, the designed wave generator has a capacity of 15mm stroke and 5.7Hz by a variable motor. A CCD camera was also mounted on the system to trace visually wave actions under centrifugal field. It was proved that the system successfully functions under as much as 100G centrifugal acceleration. It was found that the shape of paddle plays an important role to determine the characteristics of wave generated and four paddles were made and tested to find the best shape. A series of productive tests was carried out to see the responses of pore water pressure in a sand layr due to wave action, revealing that excess pore water pressure of as much as 1.2 kPa was generated, leading a liquefaction phenomenon. The test system established in this study could be applied to examine the stability of structure constructed in or on a sandy layr during wave actions. The outcomes of this research are to appear in two papers, one is "Development of minidrum centrifuges and a few initial tests" in the Proceeding of Recent Development of Soil Mechanics and Pavement Mechanics" to be held in Rio de Janeiro, the other is a domestic meeting of Chugoku Region on Soil Mechanics and Foundation Engineering.