土石壩的評(píng)估和修復(fù)畢業(yè)設(shè)計(jì)外文翻譯

1、<p><b>　　中文2575字</b></p><p><b>　　附錄一 外文翻譯</b></p><p><b>　　英文原文</b></p><p>　　Assessment and Rehabilitation of Embankment Dams</p><

2、;p>　　Nasim Uddin, P.E., M.ASCE1</p><p>　　Abstract: A series of observations, studies, and analyses to be made in the field and in the office are presented to gain a proper understanding of how an embankme

3、nt dam fits into its geologic setting and how it interacts with the presence of the reservoir it impounds. It is intended to provide an introduction to the engineering challenges of assessment and rehabilitation of emban

4、kments, with particular reference to a Croton Dam embankment.</p><p>　　DOI: 10.1061/(ASCE)0887-3828(2002)16:4(176)</p><p>　　CE Database keywords: Rehabilitation; Dams, embankment; Assessment.<

5、;/p><p>　　Introduction</p><p>　　Many major facilities, hydraulic or otherwise, have become very old and badly deteriorated; more and more owners are coming to realize that the cost of restoring the

6、ir facilities is taking up a significant fraction of their operating budgets. Rehabilitation is, therefore, becoming a major growth industry for the future. In embankment dam engineering, neither the foundation nor the f

7、ills are premanufactured to standards or codes, and their performance correspondingly is never 100% predictable. Da</p><p>　　In spite of advances in related technologies, however, it is likely that the build

8、ing of embankments and therefore their maintenance, monitoring, and assessment will remain an empirical process. It is, therefore, difficult to conceive of a set of rigorous</p><p>　　assessment procedures fo

9、r existing dams, if there are no design codes. Many agencies (the U.S. Army Corps of Engineers, USBR, Tennessee Valley Authority, FERC, etc.) have developed checklists for field inspections, for example, and suggested fo

10、rmats and topics for assessment reporting. However, these cannot be taken as procedures; they serve as guidelines, reminders, and examples of what to look for and report on, but they serve as no substitute for an experie

11、nced, interested, and observant engi</p><p>　　Rehabilitation Measures</p><p>　　The main factors affecting the performance of an embankment dam are (1)seepage; (2)stability; and (3) freeboard. Fo

12、r 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

13、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 seep</p><p>　　may eliminate or reduce these co

14、ncerns. 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 g

15、iven 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 bee

16、n used with success in raisi</p><p>　　achieved by a single measure. Usually a combination of measures, such as the installation of a cutoff plus a pressure relief system, is used. In rehabilitation work, the

17、 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

18、 the existing dam must be an overriding concern. It is not uncommon for the dam to have suffered significant di</p><p>　　The dam may be in poor condition at the outset and may possibly be in a marginally sta

19、ble 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.

20、 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.</p><p>　　Case Study</p

21、><p>　　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 spillwa

22、y, and a concrete and masonry powerhouse. The earth embankments of this project were constructed of sand with concrete core walls. The embankments were built using a modified hydraulic fill method. This method consisted

23、of dumping the sand and then sluicing the sand into the desired location. Cro</p><p>　　the design earthquake shaking. The available strength was compared with expected maximum earthquake conditions so that t

24、he stability of the embankment during and immediately after an earthquake could be evaluated. The evaluation showed that the</p><p>　　embankment had a strong potential to liquefy and fail during the design e

25、arthquake. The minimum soil strength required to eliminate the liquefaction potential was then determined, and a recommendation was made to strengthen the embankment soils by insitu densification. </p><p>　　

26、Seismic Evaluation</p><p>　　Two modes of failure were considered in the analyses—namely, loss of stability and excessive deformations of the embankment. The following analyses were carried out in succession:

27、 (1) Determination of pore water pressure buildup immediately following the design earthquake; (2) estimation of strength for the loose foundation layer during and immediately following the earthquake; (3) analysis of th

28、e loss of stability for postearthquake loading where the loose sand layer in the embankment is comple</p><p>　　Liquefaction Impact Assessment</p><p>　　Based on the average of the corrected SPT v

29、alue and cyclic stress ratio (Tokimatsu and Seed 1987), a total settlement of the 4.6 m(15 ft) thick loose embankment layer due to complete liquefaction was found to be 0.23 m (0.75 ft).</p><p>　　Permanent D

30、eformation Analysis</p><p>　　Based on a procedure by Makdisi and Seed (1977), permanent deformation can be calculated using the yield acceleration, and the time history of the averaged induced acceleration.

31、Since the factor of safety against flow failure immediately following the</p><p>　　earthquake falls well short of that required by FERC, the Newmark type deformation analysis is unnecessary. Therefore, it ca

32、n be concluded that the embankment will undergo significant permanent deformation following the earthquake, due to slope failure in excess of the liquefaction-induced settlement of 0.23 m (0.75ft).</p><p>　　

33、Embankment Remediation</p><p>　　Based on the foregoing results, it was recommended to strengthen the embankment by in situ densification. An analysis was carried out to determine the minimum soil strength re

34、quired to eliminate the liquefaction potential. The analysis was divided into three parts, as follows. First, a slope stability analysis @using the computer program PCSTABL (Purdue 1988)# of the downstream slope of the l

35、eft embankment was conducted. Strength and geometric parameters were varied in order to determine the min</p><p>　　resistance value (N1) of 60. From this value, a backcalculation was performed to determine t

36、he minimum field measure standard penetration resistance N values (blows per foot). Third, liquefaction potential was reevaluated based on the minimum zone of strengthening and minimum strength in order to show that if t

37、he embankment is strengthened to the minimum value, then the liquefaction potential in the downstream slope of the left embankment will, for all practical purposes, be eliminated.</p><p>　　Conclusion</p&g

38、t;<p>　　Key factors to be considered in dam assessment and rehabilitation are the completeness of design, construction, maintenance and monitoring records, and the experience, background, and competence of the ass

39、essing engineer. The paper presents a recently completed project to show that the economic realization of this</p><p>　　type of rehabilitation inevitably rests to a significant degree upon the expertise of t

40、he civil engineers.</p><p>　　References</p><p>　　Duncan, J. M., Seed, R. B., Wong, K. S., and Ozawa, U. (1984). ‘‘FEADAM: A computer program for finite element analysis of dams.’’ Geotechnical

41、 Engineering Research Rep. No. SU/GT/84-03,Dept. of Civil Engineering, Stanford Univ., Stanford, Calif.</p><p>　　FERC. (1993). ‘‘Engineering guidelines for the evaluation of hydropower projects.’’ 0119-2

42、.</p><p>　　Makdisi, F. I., and Seed, H. B. (1977). ‘‘A simplified procedure forestimating</p><p>　　earthquake induced deformations in dams and embankments.’’ Rep. No. EERC 77-19, Univ. of Califo

43、rnia, Berkeley, Calif.</p><p>　　Purdue Univ. (1988). ‘‘PCSTABL: A computer program for slope stability analysis.’’ Rep., West Lafayette, Ind.</p><p>　　Schnabel, P. B., Lysmer, J, and Seed, H. B.

44、 (1972). ‘‘SHAKE: A computer program for earthquake response analysis of horizontally layered site.’’ Rep. No. EERC 72-12, Univ. of California, Berkeley, Calif.</p><p>　　Seed and Harder. (1990). ‘‘An SPT-bas

45、ed analysis of cyclic pore pressure generation and undrained residual strength.’’ Proc., H. Bolton Seed Memorial Symp., 2, 351–376.</p><p>　　Tokimatsu, K., and Seed, H. B. (1987). ‘‘Evaluation of settlements

46、 of sands due to earthquake shaking.’’ J. Geotech. Eng., 113(8), 861–878.</p><p><b>　　中文翻譯</b></p><p><b>　　土石壩的評(píng)估和修復(fù)</b></p><p>　　摘要：在野外實(shí)地、辦公室里已進(jìn)行的一系列的觀察，研究，

47、分析，使本文獲得了對(duì)石壩如何適應(yīng)其地質(zhì)環(huán)境，以及如何與水庫(kù)相互影響的正確的認(rèn)識(shí)。本文旨在通過對(duì)克羅頓堤壩進(jìn)行的的案例分析，介紹大壩評(píng)估和修復(fù)過程中會(huì)遇到的技術(shù)難題。</p><p><b>　　引言</b></p><p>　　水利或其他工程上的許多大型設(shè)備，已經(jīng)非常陳舊且磨損嚴(yán)重；更多的業(yè)主逐漸意識(shí)到維護(hù)設(shè)施的費(fèi)用在運(yùn)營(yíng)成本里所占的比重越來越大。因此，未來修復(fù)產(chǎn)業(yè)將

48、會(huì)蓬勃發(fā)展。在土石壩建設(shè)工程上，無論是地基還是填土質(zhì)量都不能在生產(chǎn)前達(dá)到標(biāo)準(zhǔn)或規(guī)范，并且也不能100%預(yù)測(cè)出他們的性能表現(xiàn)。大壩建造工程，尤其是土質(zhì)結(jié)構(gòu)工程，在許多方面已經(jīng)取得進(jìn)步并將繼續(xù)改進(jìn)，特別是在節(jié)約資源和可接受風(fēng)險(xiǎn)水平的測(cè)定方面更是需要改進(jìn)。因此在該領(lǐng)域，仍存在多種改進(jìn)意見和實(shí)踐方法。因?yàn)樵擃I(lǐng)域沒有公認(rèn)的標(biāo)準(zhǔn)或唯一的施工程序，設(shè)計(jì)和建造大壩過程中可能會(huì)遇到一些工程建設(shè)上的問題。盡管相關(guān)技術(shù)有所進(jìn)步，但是這些技術(shù)很大一部分是關(guān)于大

49、壩建造的，而對(duì)其維護(hù)，監(jiān)測(cè)和評(píng)估方面的技術(shù)都處在實(shí)驗(yàn)階段。因此，如果沒有統(tǒng)一的設(shè)計(jì)規(guī)范，很難制定出一套嚴(yán)格的對(duì)建成大壩的評(píng)估制度。許多機(jī)構(gòu)（美國(guó)陸軍工程兵團(tuán)，田納西流域管理局，聯(lián)邦能源監(jiān)管委員會(huì)等）已經(jīng)開發(fā)出用于實(shí)地檢測(cè)的核對(duì)表，例如，可行的評(píng)估報(bào)告和主題。但是這些不能被當(dāng)做固定程序，只能充當(dāng)指導(dǎo)，參考，或作為需要觀察，記錄之處的范例。這種核對(duì)表決不能代替一個(gè)有經(jīng)驗(yàn)的，觀察力極強(qiáng)的工程師。在業(yè)主同意施工后，工程師應(yīng)</p>

50、<p><b>　　修復(fù)措施</b></p><p>　　影響堤壩性能的主要因素有：(1)滲流( 2)穩(wěn)定性 （3）超高。 對(duì)于一個(gè)堤壩來說，所有這些因素都是相關(guān)聯(lián)的，滲流會(huì)導(dǎo)致腐蝕和管道滲漏，使大壩失穩(wěn)。失穩(wěn)則會(huì)導(dǎo)致壩體開裂，反過來會(huì)導(dǎo)致滲漏和腐蝕。為提高大壩的穩(wěn)定性，防止?jié)B漏管涌所采取的措施取決于溢出點(diǎn)位置（地基還是壩體），滲流量及其臨界值。加高路堤邊坡穩(wěn)定性通常要通過填平斜

51、坡或是加重壓腳。這種斜坡加固工程通常會(huì)結(jié)合下游坡腳的排水措施。如果擔(dān)心快速水位下降情況下的上流坡面的穩(wěn)定性會(huì)下降，那么深入分析或監(jiān)測(cè)產(chǎn)生的孔隙水的壓力或微調(diào)水庫(kù)的操作方式會(huì)消除（對(duì)于失穩(wěn)）的顧慮。最后加高土壩通常是相對(duì)簡(jiǎn)單的填充操作，尤其是加高程度相對(duì)較小的填充操作更為簡(jiǎn)單。新舊填充物的接觸面必須在設(shè)計(jì)和建造時(shí)被給予足夠的關(guān)注以確保防水層和相關(guān)過濾器是一個(gè)連貫的整體。相對(duì)較新的材料，如防水的土工膜和加固土已被成功運(yùn)用于大壩的加高工程。然

52、而，單靠這一解決措施，大壩修復(fù)程度收效甚微。通常，需結(jié)合多種解決措施，如安裝一個(gè)帶減壓系統(tǒng)的截流器。在修復(fù)工程中，維護(hù)的效果是很難預(yù)測(cè)的。通常，在修復(fù)過程中進(jìn)行階段性的監(jiān)測(cè)和儀器的評(píng)估是很必要的。在大壩修復(fù)過程中，必須高度重視建成大壩的</p><p>　　在開始修復(fù)的時(shí)候，大壩或許處于非常糟糕的狀況或極不穩(wěn)定的條件。因此，修復(fù)工作進(jìn)展的如何會(huì)改變現(xiàn)有的大壩情況，無論是從大壩建設(shè)期或是長(zhǎng)遠(yuǎn)來看，得一直進(jìn)行對(duì)其評(píng)估

53、和修復(fù)。接下來的文章里，將對(duì)克羅頓大壩工程維護(hù)案例進(jìn)行分析，以此來介紹大壩修復(fù)過程中可能遇到的問題。</p><p><b>　　案例研究</b></p><p>　　克羅頓大壩工程坐落于密歇根州境內(nèi)的馬斯基根河上。工程的經(jīng)營(yíng)權(quán)和管理權(quán)歸消費(fèi)者電力公司所有。工程結(jié)構(gòu)包括兩座土石壩，一座有閘溢洪道，一座以混凝土和漿砌石修建的電站。工程中的土石壩屬于砂石混凝土心墻壩。土石

54、壩的填筑采用改進(jìn)的水力沖填方法。這種方法包括傾倒沙子，然后泄水將沙子沖到所需的位置?？肆_頓大壩被列為一個(gè)“高度危險(xiǎn)”的大壩，大壩所在地震區(qū)為1區(qū)。對(duì)克爾頓壩左側(cè)下游斜坡進(jìn)行的震后穩(wěn)定性評(píng)估是聯(lián)邦能源監(jiān)管委員會(huì)的1993年的監(jiān)測(cè)項(xiàng)目第12部分中的一部分。按以下方式對(duì)克羅頓堤壩進(jìn)行分析。土壤參數(shù)選擇基于標(biāo)準(zhǔn)貫入值（N）和實(shí)驗(yàn)室試驗(yàn)數(shù)據(jù)，并對(duì)大壩進(jìn)行了抗震研究以獲得設(shè)計(jì)地震烈度。采用所選擇的土壤特性,以靜態(tài)有限元方法進(jìn)行研究，來評(píng)估堤壩現(xiàn)有的

55、應(yīng)力狀態(tài)。然后進(jìn)行一維動(dòng)態(tài)分析，以確定設(shè)計(jì)地震烈度引起的應(yīng)力。將堤壩的現(xiàn)有強(qiáng)度與預(yù)期最大地震影響進(jìn)行比較，這樣就可以對(duì)堤壩在地震期間以及震后瞬時(shí)的穩(wěn)定性進(jìn)行評(píng)估。評(píng)估結(jié)果表明，在設(shè)計(jì)地震影響下，堤壩很有可能會(huì)發(fā)生液化和潰壩。土體的最低強(qiáng)度要求消除土體中潛在的液化影響，并且建議通過現(xiàn)場(chǎng)壓實(shí)來提高堤壩土體的強(qiáng)度。</p><p><b>　　抗震評(píng)價(jià)</b></p><p&g

56、t;　　在分析中考慮了兩種失敗模式，即大壩失穩(wěn)和大壩過度變形，緊接著又進(jìn)行了如下分析：（1）震后瞬時(shí)的孔隙水壓力測(cè)定；（2)震后松散地基表面評(píng)估；（3）震后對(duì)大壩填土中的疏松砂巖層的液化程度分析；（4）震后砂巖層液化產(chǎn)生的影響。 </p><p><b>　　液化影響評(píng)價(jià)</b></p><p>　　根據(jù)修正的后的標(biāo)準(zhǔn)貫入試驗(yàn)值的平均值和循環(huán)應(yīng)力比，在總共沉降的4.6

57、m（15英尺）松散圖層中，由于液化產(chǎn)生的沉降為0.23m（0.75英尺）。</p><p><b>　　永久變形分析</b></p><p>　　基于Makdisi和Seed（1977）的程序，永久變形可以使用屈服加速度計(jì)算，還可以用平均感應(yīng)加速度的時(shí)間歷程來計(jì)算。由于針對(duì)流量損失的安全系數(shù)隨地震影響而變化，且聯(lián)邦能源管制委員會(huì)在這方面的規(guī)定較缺乏，因此紐馬克型變形分

58、析并不是必要的。因此，可以得出結(jié)論：在地震發(fā)生后由于液化引起的沉降超過0.23m（0.75英尺），將引起邊坡的失穩(wěn)，最終將導(dǎo)致堤壩發(fā)生顯著的永久變形。</p><p><b>　　堤防整治</b></p><p>　　基于上述分析結(jié)果，建議通過現(xiàn)場(chǎng)壓實(shí)的方法加固大壩。通過分析，已經(jīng)測(cè)定了能消除砂礫液化可能性的最小砂礫表面張力。這項(xiàng)分析如下所述分為三部分。第一，進(jìn)行對(duì)大

59、壩下游左側(cè)斜坡的穩(wěn)定性測(cè)試。使用不同的強(qiáng)度和幾何參數(shù)以確定最小剪力強(qiáng)度和最小的土壤加強(qiáng)帶。第二，對(duì)標(biāo)準(zhǔn)貫入試驗(yàn)進(jìn)行了修正。最小的殘余剪切強(qiáng)度對(duì)應(yīng)于一個(gè)規(guī)范化的貫入阻力值（N1)。根據(jù)這個(gè)值，進(jìn)行反算來確定最小慣入標(biāo)準(zhǔn)值。第三，基于最小土壤加強(qiáng)帶和最大土壤加強(qiáng)帶的數(shù)值重新評(píng)估沙礫的液化潛能，以顯示假設(shè)大壩加固到最低值，那時(shí)在壩體左側(cè)下游坡面的潛在液化危險(xiǎn)是否被消除。</p><p><b>　　結(jié)論<