EAGER: Effect of Dimensionless Particle Weight on Maximum, Minimum, and Critical State Void Ratios

EAGER：无量纲颗粒重量对最大、最小和临界状态空隙率的影响

• 批准号: 1327233
• 负责人: Bruce Kutter
• 金额: $ 9.97万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1327233&HistoricalAwards=false
• 关键词: EAGER; Effect; Dimensionless; Particle; Weight

This EArly Grant for Exploratory Research (EAGER) award provides funding to test two hypotheses regarding the effect of dimensionless particle weight on maximum, minimum, and critical state void ratios. It has been established that van der Waals attractive forces between sand particles are approximately equal to the particle weights for very fine sands. For silt-sized particles van der Waals attractive forces can be much greater than the particle weight. The general hypothesis (Hypothesis 1) of this research is: if the attractive forces between soil particles are significant compared to the weight of the particles, the attractive forces will affect the densification and resultant void ratio of the particles. A more specific hypothesis (Hypothesis 2) is that the dimensionless particle weight, Wa = (particle weight)/(attractive force), can be used to characterize the importance of attractive forces with respect to their effect on void ratio and densification. These hypotheses will be tested by a series of experiments that vary the dimensionless particle weight while measuring the maximum, minimum and critical state void ratios of a selected idealized soil (glass spheres) and a real silica sand. The dimensionless weight due to van der Waals forces will be varied by 3 methods: changing the particle size, changing the pore fluid (air or water), and changing particle weight by spinning the soil in a geotechnical centrifuge. If the general hypotheses (Hypothesis 1) is proven true, then the maximum and minimum void ratios (common ASTM index tests used to calculate the Relative Density of soil) measured in the laboratory in earth's gravity would not be directly applicable to soils in other g-fields (e.g., geotechnical centrifuge model tests). It follows that the Relative Densities reported for hundreds of valuable geotechnical centrifuge test programs may need to be corrected or re-interpreted. If the specific hypothesis (Hypothesis 2) proves correct, a method for correcting or performing the re-interpretation may be illuminated. This project's work on this aspect of particle size effects could reshape our general understanding of the effect of particle size on the strength and dilatancy of geomaterials; this understanding is of fundamental importance in design of foundations for buildings, bridges and other infrastructure.

EARLY探索性研究奖（EAGER）提供资金来测试两个假设，即无量纲颗粒重量对最大、最小和临界状态空隙比的影响。 已经确定，砂粒之间的货车德瓦耳斯吸引力近似等于极细砂的颗粒重量。 对于粉粒级颗粒，货车范德华吸引力可能远大于颗粒重量。 本研究的一般假设（假设1）是：如果土颗粒之间的吸引力与颗粒的重量相比是显著的，则吸引力将影响颗粒的致密化和由此产生的孔隙比。 一个更具体的假设（假设2）是，无因次颗粒重量Wa =（颗粒重量）/（吸引力），可用于表征吸引力对孔隙比和致密化影响的重要性。 这些假设将通过一系列实验进行测试，这些实验改变无量纲颗粒重量，同时测量所选理想化土壤（玻璃球）和真实的硅砂的最大、最小和临界状态孔隙比。 货车德瓦尔斯力引起的无量纲重量将通过3种方法改变：改变颗粒尺寸、改变孔隙流体（空气或水）以及通过在土工离心机中旋转土壤来改变颗粒重量。 如果一般假设（假设1）被证明是正确的，那么在实验室中在地球重力下测量的最大和最小孔隙比（用于计算土壤相对密度的常见ASTM指数测试）将不直接适用于其他g场的土壤（例如，土工离心模型试验）。 因此，数百个有价值的土工离心试验程序报告的相对密度可能需要校正或重新解释。 如果特定假设（假设2）被证明是正确的，则可以阐明用于校正或执行重新解释的方法。 该项目在颗粒尺寸效应方面的工作可以重塑我们对颗粒尺寸对地质材料强度和粘性影响的一般理解;这种理解在建筑物，桥梁和其他基础设施的基础设计中具有根本的重要性。