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首页> 外文学位 >Empirical modeling of piping along Mississippi River levees in southwestern Illinois.
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Empirical modeling of piping along Mississippi River levees in southwestern Illinois.

机译：伊利诺伊州西南部密西西比河堤防沿线管道的经验模型。

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摘要

Piping beneath levees within the Middle Mississippi River, MMR, has been well documented for 78 years, when the Mississippi River Commission initiated geological investigations into underseepage following a substantial flood in 1937. The United States Army Corps of Engineers (USACE) defines a levee as an embankment designed to supply flood protection from seasonal high water. Piping is the "active erosion of sand or other soil from the top stratum as a result of substratum pressure and concentration of seepage in localized channels" (USACE, 1956a). The geological investigations beginning in 1937, and still continuing today, have consistently listed two conditions necessary for piping to occur: 1) a pervious substratum overlain (2) by a semi- to impervious top stratum (Fisk, 1945; Turnbull and Mansur, 1959). The phrase "conducive environment" is used for this type of environment. Where these factors are present during the time when a levee is subjected to water loading, the force exerted by the weight of water on the riverside of the levee can be transferred through the pervious substratum to the landside, resulting in a hydrostatic imbalance between strata and the surface landside of the levee (Turnbull and Mansur, 1959; USACE, 2000).;Innumerable miles of levee along the MMR and other rivers meet the "conducive environment" susceptible to piping and merit maintenance and piping prevention measures. Several secondary factors were identified in previous studies resulting in detailed geological investigations of all known levee districts meeting the "conducive environment". However, limited funding complicates data management and therefore, adequate piping prevention measures, along these levees. Using the Glynn and Kuszmaul (2004) database for PDR and FTC, several datasets were defined for regression analysis to develop a model that improves the efficiency of vulnerability assessments of the vast lengths of levees managed by the USACE. Single-variable regression analysis, to determine significance of each independent variable, and multi-variable regression analysis, to determine the final models for the datasets, were conducted during model building. Several possible models for each dataset were created using a modified forward stepwise regression procedure, also called a stepwise regression procedure, as suggested by Le (2010). Model selection was based on the chi-square statistic value and each models performance under thresholds discussed in subsection 4.3.1.;The model building process presented in this study proved to be a successful method for developing regression models meant to predict the potential for piping given the availability, or lack, of geologic and flood specific data. The final selected model, Limited Previous Model A, significantly predicted areas of high, medium, and low potential for piping along three levee districts; Prairie du Rocher Levee District (PDR), Fort Chartres Levee District (FTC), and East Cape Girardeau Levee District (ECG). The high significance of this model is largely attributed to the inclusion of previous piping events and interaction terms.
机译：MMR在密西西比河中部的堤防下进行管道铺设已有78年的记录，当时密西西比河委员会在1937年发生大水灾后对下渗进行了地质调查。美国陆军工程兵团（USACE）将堤防定义为旨在为季节性高水位提供防洪保护的堤防。管道是“由于地下压力和局部渠道渗流的集中而从上层开始对砂或其他土壤的积极侵蚀”（USACE，1956a）。从1937年开始并一直持续到今天的地质调查一直列出了发生管道发生的两个必要条件：1）透水层覆盖在上层（2）到半透水层（Fisk，1945； Turnbull和Mansur，1959） ）。短语“有益的环境”用于这种类型的环境。如果在堤坝受水期间存在这些因素，则由堤坝河边的水的重量所施加的力可能会通过透水的地下层转移到土地上，从而导致地层和地层之间的静水力失衡。堤防的表层陆地（Turnbull和Mansur，1959； USACE，2000）。沿MMR和其他河流无数英里的堤防符合“有利环境”，易于进行管道运输，并应进行维护和管道预防措施。在先前的研究中确定了几个次要因素，从而对符合“有利环境”的所有已知堤防区进行了详细的地质调查。但是，有限的资金使数据管理复杂化，因此，沿这些堤防采取了适当的管道预防措施。使用针对PDR和FTC的Glynn和Kuszmaul（2004）数据库，定义了几个数据集进行回归分析，以开发模型，从而提高了USACE管理的大范围堤防脆弱性评估的效率。在模型构建过程中，进行了单变量回归分析（以确定每个自变量的重要性）和多变量回归分析（确定数据集的最终模型）。根据Le（2010）的建议，使用改进的正向逐步回归程序（也称为逐步回归程序）为每个数据集创建了几种可能的模型。模型的选择基于卡方统计值，并且每个模型在第4.3.1节中讨论的阈值下的性能；该研究提出的模型构建过程被证明是开发用于预测管道潜在潜力的回归模型的成功方法考虑到地质和洪水特定数据的可用性或缺乏性。最终选择的模型，即“有限先前模型A”，显着预测了沿三个堤防区的管道的高，中和低潜力区域；大草原上的罗彻河堤防区（PDR），沙特尔斯堡堡垒堤防区（FTC）和东开普吉拉多堤防区（ECG）。该模型的高度意义很大程度上归因于先前管道事件和相互作用项的包含。

著录项

  • 作者

    Shields, Rebecca.;

  • 作者单位

    The University of Mississippi.;

  • 授予单位 The University of Mississippi.;
  • 学科 Geological engineering.;Civil engineering.;Geology.
  • 学位 M.S.
  • 年度 2015
  • 页码 120 p.
  • 总页数 120
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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