土石壩的評估和修復(fù)畢業(yè)設(shè)計(jì)外文翻譯-其他專業(yè)-文庫吧
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【正文】 ion of such things and furthermore has demonstrated his/her understanding and experience. Rehabilitation Measures The main factors affecting the performance of an embankment dam are (1)seepage。 (2)stability。 and (3) freeboard. For an embankment dam, all of these factors are interrelated. Seepage may cause erosion and piping, which may lead to instability. Instability may cause cracking, which, in turn, may cause piping and erosion failures. The measures taken to improve the stability of an existing dam against seepage and piping will depend on the location of the seepage (foundation or embankment), the seepage volume, and its criticality. Embankment slope stability is usually improved by ?attening the slopes or providing a toe berm. This slope stabilization is usually bined with drainage measures at the downstream toe. If the stability of the upstream slope under rapid drawdown conditions is of concern, then further analysis and/or monitoring of resulting pore pressures or modi?cations of reservoir operations may eliminate or reduce these concerns. Finally, raising an earth ?ll dam is usually a relatively straightforward ?ll placement operation, especially if the extent of the raising is relatively small. The interface between the old and new ?lls must be given close attention both in design and construction to ensure the continuity of the impervious element and associated filters. Relatively new materials, such as the impervious geomembranes and reinforced earth, have been used with success in raising embankment dams. Rehabilitation of an embankment dam, however, is rarely achieved by a single measure. Usually a bination of measures, such as the installation of a cutoff plus a pressure relief system, is used. In rehabilitation work, the effectiveness of the repairs is difficult to predict。 often, a phased approach to the work is necessary, with monitoring and instrumentation evaluated as the work proceeds. In the rehabilitation of dams, the security of the existing dam must be an overriding concern. It is not unmon for the dam to have suffered significant distress—often due to the deficiencies that the rehabilitation measures are to address. The dam may be in poor condition at the outset and may possibly be in a marginally stable condition. Therefore, how the rehabilitation work may change the present conditions, both during construction and in the long term, must be assessed, to ensure that it does not adversely affect the safety of the dam. In the following text, a case study is presented as an introduction to the engineering challenges of embankment rehabilitation, with particular reference to the Croton Dam Project. Case Study The Croton Dam Project is located on the Muskegon River in Michigan. The project is owned and operated by the Consumer Power Company. The project structures include two earth embankments, a gated spillway, and a conc
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