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Field measurements of the linear and nonlinear shear moduli of cemented alluvium using dynamically loaded surface footings.

机译：使用动态加载的表面基础对胶结冲积层的线性和非线性剪切模量进行现场测量。

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摘要

In this dissertation, a research effort aimed at development and implementation of a direct field test method to evaluate the linear and nonlinear shear modulus of soil is presented. The field method utilizes a surface footing that is dynamically loaded horizontally. The test procedure involves applying static and dynamic loads to the surface footing and measuring the soil response beneath the loaded area using embedded geophones. A wide range in dynamic loads under a constant static load permits measurements of linear and nonlinear shear wave propagation from which shear moduli and associated shearing strains are evaluated. Shear wave velocities in the linear and nonlinear strain ranges are calculated from time delays in waveforms monitored by geophone pairs. Shear moduli are then obtained using the shear wave velocities and the mass density of a soil. Shear strains are determined using particle displacements calculated from particle velocities measured at the geophones by assuming a linear variation between geophone pairs.;The field test method was validated by conducting an initial field experiment at sandy site in Austin, Texas. Then, field experiments were performed on cemented alluvium, a complex, hard-to-sample material. Three separate locations at Yucca Mountain, Nevada were tested. The tests successfully measured: (1) the effect of confining pressure on shear and compression moduli in the linear strain range and (2) the effect of strain on shear moduli at various states of stress in the field. The field measurements were first compared with empirical relationships for uncemented gravel. This comparison showed that the alluvium was clearly cemented. The field measurements were then compared to other independent measurements including laboratory resonant column tests and field seismic tests using the spectral-analysis-of-surface-waves method. The results from the field tests were generally in good agreement with the other independent test results, indicating that the proposed method has the ability to directly evaluate complex material like cemented alluvium in the field.
机译：本文提出了一种研究方法，旨在开发和实现一种直接测试方法来评估土壤的线性和非线性剪切模量。现场方法利用水平动态加载的表面基础。测试程序包括对地面基础施加静态和动态载荷，并使用嵌入式地震检波器测量载荷区域下方的土壤响应。在恒定静载荷下的宽动态载荷范围允许测量线性和非线性剪切波传播，从中可以评估剪切模量和相关的剪切应变。线性和非线性应变范围内的剪切波速度是根据地震检波器对所监测波形的时间延迟来计算的。然后使用剪切波速度和土壤的质量密度获得剪切模量。剪切应变是通过假设在检波器对之间的线性变化，使用由在检波器处测量的粒子速度计算出的粒子位移来确定的。现场测试方法通过在德克萨斯州奥斯汀的沙地进行初始现场实验而得到验证。然后，对胶结冲积层进行了现场试验，胶结冲积层是一种复杂的，难以采样的材料。对内华达州尤卡山的三个不同地点进行了测试。测试成功地测量出：（1）在线性应变范围内，围压对剪切模量和压缩模量的影响；（2）在现场各种应力状态下应变对剪切模量的影响。首先将现场测量结果与未胶结砾石的经验关系进行比较。该比较表明，冲积层明显胶结。然后将现场测量结果与其他独立测量结果进行比较，包括实验室共振柱测试和使用表面波频谱分析方法进行的现场地震测试。田间试验的结果通常与其他独立试验结果吻合良好，这表明所提出的方法具有直接评估田间胶结冲积层等复杂材料的能力。

著录项

  • 作者

    Park, Kwangsoo.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Geophysics.;Engineering Civil.;Engineering Geophysical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 383 p.
  • 总页数 383
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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