Stability of a levee modelled in a geotechnical drum centrifuge.

在岩土转鼓离心机中模拟的堤坝稳定性。

基本信息

批准号：
60550342
负责人：
KUSAKABE Osamu
金额：
$ 1.28万
依托单位：
University of Utsunomiya
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550342/
关键词：
drum centrifuge model test stability of levee stability problems pipe flow パイプフロー相似則

项目摘要

The first drum centrifuge in Japan was designed and constructed to study the stability problems of long soil structures, such as embankments, levees. The drum has the diameter of 0.8 m , the width of 0.3 m and the depth of 0.1 m , and can be spinned up to 150 g, producing the prototype behaviour of a soil model of 377 m long, 45 m wide and 15 m deep. The achievement of this study can be summarized in the following points.1. Safety operation of the drum centrifuge has continued for over one thousand hours by the end of Feburary,1987, which gives us a confidence of utilizing a drum centrifuge as an useful experimental tool for modeling geotechnical problems.2. Experimental technique of production of a normally consolidated clay layer overlain by a levee of compacted soils in the drum has been established.3. Modeling technique of levee failures during flood has been sucessfully developed. A series of model tests with different soil type was carried out. Close observation suggests that the process of failure of a levee may be understood by using an analogy of stability of shallow tunnels. Observed process of failure was as follows:As the level of water raises, the first erosion is occurred at the surface of a levee slope, and that a pipe flow is created by hydraulic fracture and seeping water reaches at the surface of the levee slope on the inland side. As the result of flushing out the soil particles, the diameter of the pipe flow gradually widens. Our knowlegde of the stability of of a shallow tunnel tells us that the stability of the pipe is gorverned by the ratio of the cover of the pipe to the diameter of the pipe, and by the cohesion and the unit weight of the soil. For soils having higher cohesion, the pipe remains stable up to relatively larger diamter, whereas soils having less cohesion, the pipe collapes when the diamter becomes a certain value, resulting the total failure of the levee.

日本的第一个鼓离心设备是设计和构建的，以研究长土壤结构（例如路堤，堤防）的稳定性问题。鼓的直径为0.8 m，宽度为0.3 m，深度为0.1 m，可以旋转至150 g，从而产生377 m长，45 m宽和15 m深的土壤模型的原型行为。可以在以下几点中总结本研究的实现1。在1987年2月底之前，鼓离心的安全操作持续了一千多小时，这使我们有信心利用鼓离心作为建模岩土技术问题的有用的实验工具。2。已经建立了正常合并的粘土层生产的实验技术。洪水期间堤防故障的建模技术已成功地开发出来。进行了一系列具有不同土壤类型的模型测试。仔细观察表明，通过使用浅隧道稳定性的类比，可以理解堤防失败的过程。观察到的故障过程如下：随着水的升高水平，第一个侵蚀发生在堤防斜坡的表面，并且管道流是由液压裂缝和渗入水到达内陆侧面堤坝表面的水的产生的。由于冲出土壤颗粒的结果，管道的直径逐渐扩大。我们对浅隧道稳定性的知识告诉我们，管道的稳定性是由管道盖与管道直径的盖子之比，由土壤的凝聚力和单位重量的比例。对于具有较高内聚力的土壤，该管道保持稳定至相对较大的直径，而土壤的内聚力较小，当直径变为一定值时，管道倒塌，导致堤防的总失败。