Effects of soil heterogeneity on pile foundations under seismic loads

地震荷载作用下土体非均质性对桩基的影响

• 批准号: 203795-2006
• 负责人: Popescu, Radu
• 金额: $ 1.54万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2006
• 资助国家: 加拿大
• 起止时间: 2006-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=332143
• 关键词: Effects; soil; heterogeneity; pile; foundations

Seismic induced liquefaction of saturated soil is still a major cause of earthquake damage to deep foundations, in spite of relatively large safety margins used in design. This proposal outlines a combined experimental and numerical study aimed at addressing a series of questions regarding failure mechanisms and interaction forces for piles in liquefying soil that have not been answered yet, and at providing the industry with a reliable tool and guidelines for seismic design of deep foundations. It is well understood today that soil properties vary from one point to another even within geologically distinct layers. The effects of this natural soil heterogeneity on soil liquefaction and soil pile interaction will also be addressed. In this respect, recent theoretical research identified a very interesting behaviour of such natural soils subjected to seismic loads that is likely to have significant influence on design practices in earthquake geotechnical engineering. To date, there is no experimental verification available to the practicing engineering community to help in recognizing, quantifying and accepting the above-mentioned behavior of heterogeneous soils.   A series of original centrifuge experiments for seismic analysis of pile foundations in randomly heterogeneous soil are proposed in this research program to investigate the atypical soil behaviour identified in theoretical studies and to quantify its effects on deep foundations. A state-of-the-art finite element code for dynamic effective stress analysis of soil-structure systems will be calibrated based on the experimental results and used to expand the scope of the experimental program. Both experimental and numerical results will then be used to develop, calibrate and validate a computationally effective tool for seismic analysis of pile foundations, readily available for current design applications. Finally, the new tool will be used in a systematic numerical study to provide design guidelines for a wide range of field situations and seismic loads. The soil materials for experiments and the examples for theoretical developments will be selected from the Fraser River Delta in British Columbia, a densely populated region highly vulnerable to earthquake hazards and soil liquefaction.

尽管在设计中使用了相对较大的安全边缘，但地震诱导的饱和土壤液化仍然是对深层地震损害的主要原因。该提案概述了一项合并的实验和数值研究，旨在解决有关液化土壤中桩的故障机制和相互作用力的一系列问题，这些问题尚未得到解决，并为该行业提供了可靠的工具和深层地震设计的准则。如今，即使在地质上不同的层中，土壤特性也从一个点到另一点不等。这种天然土壤异质性对土壤液化和土壤桩相互作用的影响也将得到解决。在这方面，最近的理论研究确定了这种天然土壤受到地震载荷的非常有趣的行为，这可能会对地震岩土工程工程中的设计实践产生重大影响。迄今为止，实践工程界还没有实验验证来帮助识别，量化和接受异质土壤的上述行为。在本研究计划中提出了一系列针对随机异质土壤中桩基础的地震分析的原始离心机实验，以研究理论研究中发现的非典型土壤行为，并量化其对深层基础的影响。根据实验结果，将校准用于土壤结构系统的动态有效应力分析的最新有限元代码，并用于扩大实验程序的范围。然后，实验结果和数值结果均应用于开发，校准和验证一种计算有效的工具，用于对桩基础的地震分析，该工具很容易用于当前的设计应用。最后，新工具将用于系统的数值研究中，以为广泛的现场情况和地震载荷提供设计指南。将从不列颠哥伦比亚省的Fraser River Delta中选择实验的土壤材料和理论发展的实例，这是一个被人们群体的人口稠密的地区，极易受到地震危害和土壤液化的影响。