Determination of Soil Properties for In-Flight Models Using Bender Elements

使用 Bender Elements 确定飞行模型的土壤特性

• 批准号: 9728860
• 负责人: Xiangwu Zeng
• 金额: $ 7.88万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2000-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9728860&HistoricalAwards=false
• 关键词: Determination; Soil; Properties; Flight; Models

One method to simulate approximately the effects of earthquake loading on a full-size earth structure, such as an earth dam or a retaining wall, is to shake a physical model of the soil structure in-flight on a geotechnical centrifuge. The various physical simulation methods available are all approximations to reality, and it is important to understand clearly what these approximations are.Data from centrifuge experiments can be used to study the physical mechanisms involved in complex problems, as well as to verify numerical procedures, and to evaluate new design approaches. However centrifuge modeling is a complex experimental method. There are some uncertainties in modeling techniques that need further study so as to establish confidence in the accuracy of the simulation. One of the most significant uncertainties involves the soil properties in a model during the flight (rotation) of the centrifuge. It has been accepted practice to measure the properties prior to or after flight, which can be significantly different from the properties that exist during flight. It is also generally assumed that the soil samples are uniform and isotropic, basically because of the difficulty in measuring the actual degree of uniformity and isotropy. There are other approximations, which also need to be examined.The principal investigator is addressing the accuracy of the simulation by using "bender" elements (a relatively new technique) to measure the shear modulus of soil. This is a very promising approach that is expected to lead to an improved understanding of the approximations inherent in simulating on a centrifuge the earthquake loading on an earth structure.

一种近似模拟地震荷载对全尺寸土结构（如土坝或挡土墙）影响的方法是在土工离心机上摇动飞行中的土结构物理模型。 现有的各种物理模拟方法都是对现实的近似，清楚地理解这些近似是很重要的。离心实验的数据可以用来研究复杂问题中涉及的物理机制，也可以用来验证数值程序，并评估新的设计方法。 然而，离心模型是一种复杂的实验方法。 建模技术中存在一些不确定性，需要进一步研究，以建立对模拟准确性的信心。 最重要的不确定性之一涉及离心机飞行（旋转）期间模型中的土壤特性。 在飞行前或飞行后测量性能是公认的做法，这些性能可能与飞行期间存在的性能显著不同。 一般还假定土样是均匀的和各向同性的，这基本上是因为难以测量均匀性和各向同性的实际程度。 还有其他的近似方法也需要检验。主要研究人员正在通过使用“弯曲”元素（一种相对较新的技术）来测量土壤的剪切模量，从而解决模拟的准确性。 这是一个非常有前途的方法，预计将导致在离心机上模拟地球结构上的地震荷载的固有的近似值的更好的理解。