<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns="http://www.w3.org/TR/REC-html40">  <head> <meta http-equiv=Content-Type content="text/html; charset=windows-1252"> <meta name=ProgId content=Word.Document> <meta name=Generator content="Microsoft Word 9"> <meta name=Originator content="Microsoft Word 9"> <link rel=File-List href="./chapitre2_fichiers/filelist.xml"> <link rel=Edit-Time-Data href="./chapitre2_fichiers/editdata.mso"> <!--[if !mso]> <style> v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} </style> <![endif]--> <title>&#9;V.8. Zone optimale du soutirage                  </title> <!--[if gte mso 9]><xml>  <o:DocumentProperties>   <o:Author>Remini Boualem</o:Author>   <o:Template>Normal</o:Template>   <o:LastAuthor>rafed</o:LastAuthor>   <o:Revision>2</o:Revision>   <o:TotalTime>755</o:TotalTime>   <o:LastPrinted>2000-02-09T08:24:00Z</o:LastPrinted>   <o:Created>2001-02-22T14:23:00Z</o:Created>   <o:LastSaved>2001-02-22T14:23:00Z</o:LastSaved>   <o:Pages>5</o:Pages>   <o:Words>1902</o:Words>   <o:Characters>10846</o:Characters>   <o:Company> </o:Company>   <o:Bytes>99328</o:Bytes>   <o:Lines>90</o:Lines>   <o:Paragraphs>21</o:Paragraphs>   <o:CharactersWithSpaces>13319</o:CharactersWithSpaces>   <o:Version>9.2812</o:Version>  </o:DocumentProperties> </xml><![endif]--><!--[if gte mso 9]><xml>  <w:WordDocument>   <w:HyphenationZone>21</w:HyphenationZone>   <w:DrawingGridHorizontalSpacing>6 pt</w:DrawingGridHorizontalSpacing>   <w:DrawingGridVerticalSpacing>6 pt</w:DrawingGridVerticalSpacing>   <w:DisplayVerticalDrawingGridEvery>0</w:DisplayVerticalDrawingGridEvery>   <w:UseMarginsForDrawingGridOrigin/>   <w:Compatibility>    <w:SpaceForUL/>    <w:BalanceSingleByteDoubleByteWidth/>    <w:DoNotLeaveBackslashAlone/>    <w:ULTrailSpace/>    <w:DoNotExpandShiftReturn/>    <w:UsePrinterMetrics/>    <w:WW6BorderRules/>    <w:FootnoteLayoutLikeWW8/>    <w:ShapeLayoutLikeWW8/>    <w:AlignTablesRowByRow/>    <w:ForgetLastTabAlignment/>    <w:AutoSpaceLikeWord95/>    <w:LayoutRawTableWidth/>    <w:LayoutTableRowsApart/>   </w:Compatibility>  </w:WordDocument> </xml><![endif]--> <style> <!--  /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal 	{mso-style-parent:""; 	margin:0cm; 	margin-bottom:.0001pt; 	mso-pagination:widow-orphan; 	mso-layout-grid-align:none; 	punctuation-wrap:simple; 	text-autospace:none; 	font-size:10.0pt; 	font-family:"Times New Roman"; 	mso-fareast-font-family:"Times New Roman";} @page Section1 	{size:21.0cm 842.0pt; 	margin:147.4pt 127.6pt 155.95pt 127.6pt; 	mso-header-margin:36.0pt; 	mso-footer-margin:36.0pt; 	mso-paper-source:0;} div.Section1 	{page:Section1;}  /* List Definitions */ @list l0 	{mso-list-id:-2; 	mso-list-type:simple; 	mso-list-template-ids:1246390086;} @list l0:level1 	{mso-level-start-at:0; 	mso-level-text:*; 	mso-level-tab-stop:none; 	mso-level-number-position:left; 	margin-left:0cm; 	text-indent:0cm;} @list l0:level1 lfo1 	{mso-level-start-at:1; 	mso-level-number-format:bullet; 	mso-level-numbering:continue; 	mso-level-text:\F0B7; 	mso-level-tab-stop:none; 	mso-level-number-position:left; 	mso-level-legacy:yes; 	mso-level-legacy-indent:14.15pt; 	mso-level-legacy-space:0cm; 	margin-left:14.15pt; 	text-indent:-14.15pt; 	font-family:Symbol;} ol 	{margin-bottom:0cm;} ul 	{margin-bottom:0cm;} --> </style> <!--[if gte mso 9]><xml>  <o:shapedefaults v:ext="edit" spidmax="1103"/> </xml><![endif]--><!--[if gte mso 9]><xml>  <o:shapelayout v:ext="edit">   <o:idmap v:ext="edit" data="1"/>  </o:shapelayout></xml><![endif]--> </head>  <body lang=FR style='tab-interval:35.4pt'>  <div class=Section1>  <p class=MsoNormal align=center style='text-align:center'><span style='font-size:16.0pt;mso-bidi-font-size:10.0pt;text-transform:uppercase'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal align=center style='text-align:center'><b style='mso-bidi-font-weight: normal'><span style='font-size:16.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman";text-transform:uppercase'>Zone optimale du soutirage</span></b><b style='mso-bidi-font-weight:normal'><span style='font-size:16.0pt;mso-bidi-font-size:10.0pt;font-family:Arial;mso-bidi-font-family: "Times New Roman"'><span style="mso-spacerun: yes"> </span><o:p></o:p></span></b></p>  <p class=MsoNormal align=center style='text-align:center'><span style='font-size:16.0pt;mso-bidi-font-size:10.0pt'><span style="mso-spacerun: yes"> </span><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>1. Problmatique<o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span></span></b><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt'>Le soutirage des sdiments par les vannes de fond peut rduire considrablement lenvasement des retenues en mettant  profit la prsence des courants de densit, phnomne favorable  lutilisation de cette technique. Il est mme possible daffirmer que dans les pays arides et semi arides, cette utilisation devrait tre la rgle. Or force est de constater que le soutirage est mal pratiqu en Algrie, malgr la prsence des courants de densit dans la majorit, sinon lensemble des retenues, ce qui a engendr des pertes considrables deau claire dans certains barrages, ou une volution rapide de lenvasement dans dautres provoquant ainsi leur abondons comme pour CHEURFAS I en 1966, ou le blocage de la vanne de fond comme pour OUED EL FODDA en 1948.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Cette ide nest pas nouvelle, et DESSOLIERS H. avait ds 1908 parfaitement dfini ce quil fallait faire:&nbsp;Au lieu de laisser les vases saccumuler, se tasser, se durcir, puis sacharner  les extraire, ce qui sera dautant plus coteux que lon aura attendu plus longtemps, il faut aprs chaque crue, pendant quelles sont encore semi fluides, les vacuer immdiatement par un gout de fond&nbsp;. Il est  noter qu cette poque lauteur<span style="mso-spacerun: yes"> </span>na pas trouv audience. <o:p></o:p></span></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;border:none;mso-border-top-alt: solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Allant dans le mme sens, DUQUENNOIS H. (1954), a montr que les soutirages qui ne se font pas ds larrive du courant de densit auront un rendement plus lev mais que la quantit totale des sdiments sera infrieure  celle du soutirage immdiat. Il a affirm aussi quil nest pas ncessaire de soutirer des mlanges trs denses, au risque de ne pas vacuer le maximum possible de la vase. <o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Le mme auteur avait, ds 1949<span style="mso-spacerun: yes"> </span>estim que si on pratique louverture des vannes de fond lorsque la consolidation est avance, on vacue de largile et de la vase de densit leve (plus de 1,350) mais en faible quantit; on arrive rapidement  leau claire.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>2. Influence de la concentration en lments fins sur le &nbsp;Facteur de pression&nbsp;.<o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Le facteur de pression est dfini comme tant le rapport entre la variation de la densit (</span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 68 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> = </span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><sub>m </sub>- </span><!--[if supportFields]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>) et la densit de la suspension (</span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 68 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> /</span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><sub>m </sub>=(</span><!--[if supportFields]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><sub>m</sub>-</span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>) / </span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><sub>m</sub>). Il est caractris comme la force motrice du courant de densit et comme paramtre principal du soutirage. <o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Plus<b style='mso-bidi-font-weight:normal'> </b></span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 68 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>/ </span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><sub>m</sub> est lev, plus l'vacuation des sdiments sera importante et la perte d'eau sera faible, et il ne doit pas dpasser une valeur limite de la concentration qui dpend de la nature et de la granulomtrie de la vase.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Selon DUQUENNOIS H. (1944) si les vases restent accumules pendant de longs mois sous leau, leur densit augmente en tendant vers une limite. Leur viscosit augmente trs sensiblement et bien quil sagisse encore de fluide, la viscosit est telle que lcoulement ne peut se faire quavec de trs fortes pertes de charge&nbsp;. Cette hypothse a t confirm par DROUHIN et al. (1951).<span style="mso-spacerun: yes"> </span><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify;tab-stops:241.0pt'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;tab-stops:241.0pt;border:none; mso-border-top-alt:solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style="mso-spacerun: yes"> </span>Nous avons tudi lvolution du &nbsp;facteur de pression&nbsp; en fonction de la concentration des sdiments sur des chantillons de vase vacue par les pertuis de vidange des barrages de GHRIB, OUED EL FODDA, ZARDEZAS et FOUM EL GHERZA. Les rsultats obtenus sont reprsents sur la figure<span style="mso-spacerun: yes"> </span>33 (a  d): on constate que le &nbsp;facteur de pression&nbsp; </span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 68 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>/ </span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 114 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><sub>m</sub><span style="mso-spacerun: yes"> </span>volue linairement dans une premire phase,  partir d'une valeur critique de la concentration, il y a ralentissement de ce facteur, la fonction prenant une forme parabolique.<o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Les valeurs critiques de concentrations (ou densits) sont consignes dans le tableau 8 .<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:8.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:11.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span><i style='mso-bidi-font-style:normal'>Tableau 8. Valeurs critiques de la concentration de la vase<o:p></o:p></i></span></b></p>  <p class=MsoNormal align=center style='text-align:center'><b style='mso-bidi-font-weight: normal'><i style='mso-bidi-font-style:normal'><span style='font-size:11.0pt; mso-bidi-font-size:10.0pt'>(REMINI B., 1998)</span></i></b><i style='mso-bidi-font-style: normal'><o:p></o:p></i></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:8.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <table border=0 cellspacing=0 cellpadding=0 style='margin-left:31.85pt;  border-collapse:collapse;mso-padding-alt:0cm 3.5pt 0cm 3.5pt'>  <tr>   <td width=132 valign=top style='width:99.25pt;border:solid windowtext .75pt;   border-bottom:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"> </span>Vases des <o:p></o:p></b></p>   </td>   <td width=274 colspan=2 valign=top style='width:205.55pt;border:solid windowtext .75pt;   border-left:none;mso-border-left-alt:solid windowtext .75pt;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"> </span>Valeurs critiques de la   concentration<o:p></o:p></b></p>   </td>  </tr>  <tr>   <td width=132 valign=top style='width:99.25pt;border:solid windowtext .75pt;   border-top:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"> </span>barrages<o:p></o:p></b></p>   </td>   <td width=133 valign=top style='width:99.95pt;border-top:none;border-left:   none;border-bottom:solid windowtext .75pt;border-right:solid windowtext .75pt;   mso-border-top-alt:solid windowtext .75pt;mso-border-left-alt:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"></span>Densit (</b><!--[if supportFields]><b   style='mso-bidi-font-weight:normal'><span style='mso-element:field-begin'></span>SYMBOL   114 \f &quot;Symbol&quot;</b><![endif]--><!--[if supportFields]><b   style='mso-bidi-font-weight:normal'><span style='mso-element:field-end'></span></b><![endif]--><b   style='mso-bidi-font-weight:normal'><sub>m</sub>)<o:p></o:p></b></p>   </td>   <td width=141 valign=top style='width:105.6pt;border:solid windowtext .75pt;   border-left:none;mso-border-left-alt:solid windowtext .75pt;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"></span>Concentration (g/l)<o:p></o:p></b></p>   </td>  </tr>  <tr>   <td width=132 valign=top style='width:99.25pt;border:solid windowtext .75pt;   border-top:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>GHRIB</p>   <p class=MsoNormal style='text-align:justify'>OUEDEL FODDA</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>IGHIL EMDA</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>ERRAGUENE</p>   </td>   <td width=133 valign=top style='width:99.95pt;border-top:none;border-left:   none;border-bottom:solid windowtext .75pt;border-right:solid windowtext .75pt;   mso-border-top-alt:solid windowtext .75pt;mso-border-left-alt:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,096</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,083</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,140</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,087</p>   </td>   <td width=141 valign=top style='width:105.6pt;border-top:none;border-left:   none;border-bottom:solid windowtext .75pt;border-right:solid windowtext .75pt;   mso-border-top-alt:solid windowtext .75pt;mso-border-left-alt:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>140</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>137</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>200</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>156</p>   </td>  </tr> </table>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:8.0pt;mso-bidi-font-size:10.0pt'><span style="mso-spacerun: yes"> </span></span><o:p></o:p></b></p>  <p class=MsoNormal style='text-align:justify'><span style='mso-tab-count:1'> </span><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>La mme tude a t faite sur des donnes<span style="mso-spacerun: yes"> </span>de concentration<span style="mso-spacerun: yes"> </span>enregistres au cours de diffrentes oprations de soutirage dans les barrages de GHRIB, OUED EL FODDA, ERRAGUENE et IGHIL EMDA. Les mmes interprtations peuvent tre faites et les rsultats obtenus sont reprsents sur la figure 34 (a  d). Les valeurs critiques de concentration (ou densit) sont donnes sur le tableau 9.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:8.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:11.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"> </span></span><i style='mso-bidi-font-style:normal'>Tableau 9.<span style="mso-spacerun: yes"> </span>Valeurs critiques de la concentration de la vase<o:p></o:p></i></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><i style='mso-bidi-font-style:normal'><span style="mso-spacerun: yes"> </span>(enregistres au cours de diffrentes oprations de soutirage</i><o:p></o:p></b></p>  <p class=MsoNormal align=center style='text-align:center'><i style='mso-bidi-font-style: normal'>(REMINI B., 1998)<o:p></o:p></i></p>  <p class=MsoNormal align=center style='text-align:center'><i style='mso-bidi-font-style: normal'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></i></p>  <table border=0 cellspacing=0 cellpadding=0 style='margin-left:38.95pt;  border-collapse:collapse;mso-padding-alt:0cm 3.5pt 0cm 3.5pt'>  <tr>   <td width=151 valign=top style='width:4.0cm;border:solid windowtext .75pt;   border-bottom:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"> </span>Vase des barrages <o:p></o:p></b></p>   </td>   <td width=246 colspan=2 valign=top style='width:184.3pt;border:solid windowtext .75pt;   border-left:none;mso-border-left-alt:solid windowtext .75pt;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"> </span>Valeur critique de   concentration<o:p></o:p></b></p>   </td>  </tr>  <tr>   <td width=151 valign=top style='width:4.0cm;border:solid windowtext .75pt;   border-top:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'><span style="mso-spacerun: yes"> </span><o:p></o:p></b></p>   </td>   <td width=113 valign=top style='width:3.0cm;border-top:none;border-left:none;   border-bottom:solid windowtext .75pt;border-right:solid windowtext .75pt;   mso-border-top-alt:solid windowtext .75pt;mso-border-left-alt:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>Densit(</b><!--[if supportFields]><b style='mso-bidi-font-weight:   normal'><span style='mso-element:field-begin'></span>SYMBOL 114 \f   &quot;Symbol&quot;</b><![endif]--><!--[if supportFields]><b style='mso-bidi-font-weight:   normal'><span style='mso-element:field-end'></span></b><![endif]--><b   style='mso-bidi-font-weight:normal'><sub>m</sub>)<o:p></o:p></b></p>   </td>   <td width=132 valign=top style='width:99.25pt;border:solid windowtext .75pt;   border-left:none;mso-border-left-alt:solid windowtext .75pt;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>Concentration(%)<o:p></o:p></b></p>   </td>  </tr>  <tr>   <td width=151 valign=top style='width:4.0cm;border:solid windowtext .75pt;   border-top:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span><span lang=EN-GB style='mso-ansi-language:EN-GB'>GHRIB<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=EN-GB   style='mso-ansi-language:EN-GB'><span style="mso-spacerun: yes">   </span>OUED EL FODDA<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=EN-GB   style='mso-ansi-language:EN-GB'><span style="mso-spacerun: yes">   </span></span><span lang=DE style='mso-ansi-language:DE'>IGHIL EMDA<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>ERRAGUENE<o:p></o:p></span></p>   </td>   <td width=113 valign=top style='width:3.0cm;border-top:none;border-left:none;   border-bottom:solid windowtext .75pt;border-right:solid windowtext .75pt;   mso-border-top-alt:solid windowtext .75pt;mso-border-left-alt:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span></span>1,096</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,082</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,059</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>1,070</p>   </td>   <td width=132 valign=top style='width:99.25pt;border-top:none;border-left:   none;border-bottom:solid windowtext .75pt;border-right:solid windowtext .75pt;   mso-border-top-alt:solid windowtext .75pt;mso-border-left-alt:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>14,7 %</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>14,0 %</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>10,5 %</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>11,5 %</p>   </td>  </tr> </table>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt'><span style="mso-spacerun: yes"> </span></span></b><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>52</span></b><b style='mso-bidi-font-weight: normal'><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt'><o:p></o:p></span></b></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;border:none;mso-border-top-alt: solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='mso-tab-count:1'> </span><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>En conclusion, nous pouvons dire que la valeur critique de la concentration correspondant  lapparition de la rigidit initiale soit au changement rhologique de la suspension: ceci veut dire que la suspension passe dun liquide Newtonien  un liquide non Newtonien.<o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>3. Vitesse de chute des particules fines dans une retenue <o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:14.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Nous avons tudi volution de la vitesse de chute des particules fines en fonction de leurs concentration sur des chantillons de vase vacue par les pertuis de vidange des barrages de GHRIB, OUED EL FODDA, IGHIL EMDA,<span style="mso-spacerun: yes"> </span>FOUM EL GHERZA, ZARDEZAS et HAMIZ.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Les rsultats obtenus sont reprsentes sur la figures 35 (a  e): on constate que plus la densit (ou la concentration) est leve, plus la vitesse de chute des particules fines devient<span style="mso-spacerun: yes"> </span>faible.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"></span>Ce ralentissement<span style="mso-spacerun: yes"> </span>considrable de la dcantation aux densits assez leves explique qu'il se forme en amont des vannes une couche dense au fond de la retenue dont la consolidation n'est pas immdiate et qui, peut encore s'couler sur la pente du fond. La chose est particulirement vraie lorsque les dpts dans les parties avales des cuvettes tendent donc  garder leur surface horizontale.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Avec le temps, ces dpts finissent par se consolider et<b style='mso-bidi-font-weight: normal'> </b>DUQUENNOIS H. ds 1954 a affirm que le mlange est quasi immobile aux abords du barrage. La dcantation nest pas gne par la turbulence. Elle sexerce dautant plus rapidement que la concentration est plus faible. Les derniers apports se superposent aux premiers qui, par dcantation, librent un certain volume et ainsi de suite.<o:p></o:p></span></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;text-indent:35.4pt;border:none; mso-border-top-alt:solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Mais il y'a des vases qui sont restes fluides toute la vie de l'ouvrage. En Algrie c'est bien souvent le cas; le plus bel exemple est celui des CHEURFAS I, un ouvrage compltement envas, qui aprs 70 ans d'existence prsente toujours une vase non consolide. La vitesse avec laquelle les dpts se consolident est fonction de la nature des matriaux transports et de leur granulomtrie. <o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Si les lments sableux (ou silteux) reprsentent une forte proportion du dpt, la consolidation se fera beaucoup plus rapidement et la vase pourra prendre une consistance telle quil faudra lattaquer  la pioche pour la dsagrger. DROUHIN et al<b style='mso-bidi-font-weight:normal'> </b><span style="mso-spacerun: yes"></span>ont affirm que les dpts se consolident assez vite dans la retenue de FERGOUG et les dpts nont pas toujours une consistance trs fluide. Mais cependant au barrage de lOUED EL FODDA, la vase se consolide rapidement sous leau, ce qui a dj rendu la vanne de fond<span style="mso-spacerun: yes"> </span>non manoeuvrable depuis 1948.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>4. Flux solide dans une retenue</span></b><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt;font-family:Arial;mso-bidi-font-family:"Times New Roman"'> <o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Dans un milieu solide, la dcantation est caractrise par un flux solide (dbit massique par unit de surface) symbolis par la lettre </span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 89 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> et qui est obtenu par la relation :<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><!--[if gte vml 1]><v:rect id="_x0000_s1027"  style='position:absolute;left:0;text-align:left;margin-left:149.3pt;  margin-top:4.1pt;width:78.15pt;height:28.45pt;z-index:1;  mso-position-horizontal-relative:text;mso-position-vertical-relative:text'  o:allowincell="f" filled="f"/><![endif]--><![if !vml]><span style='mso-ignore: vglayout'>  <table cellpadding=0 cellspacing=0 align=left>  <tr>   <td width=199 height=5></td>  </tr>  <tr>   <td></td>   <td><img width=105 height=39 src="./chapitre2_fichiers/image001.gif" v:shapes="_x0000_s1027"></td>  </tr> </table>  </span><![endif]><b style='mso-bidi-font-weight:normal'><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <br style='mso-ignore:vglayout' clear=ALL>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style="mso-spacerun: yes"> </span><span style="mso-spacerun: yes"></span></span></b><!--[if supportFields]><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 89 \f &quot;Symbol&quot;</span></b><![endif]--><!--[if supportFields]><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'><span style='mso-element:field-end'></span></span></b><![endif]--><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> = C. W<sub>s</sub><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Pour diffrentes valeurs de la concentration , on mesure la vitesse de chute des sdiments. Les rsultats obtenus permettent dtablir lallure de la fonction Ln Ws = f (Lne) qui est une droite d'quation : <o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:11.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:11.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;border:none;mso-border-top-alt: solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='font-size:11.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count: 1'> </span></span><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>Ln W<sub>S</sub> = n Ln(e) + Ln W<sub>P</sub> , do :<span style="mso-spacerun: yes"> </span>Ws/Wp = e<sup>n</sup>. <o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>Cest  dire : </span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span>SYMBOL 89 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>=C.W<sub>P </sub>. e<sup>n </sup>. Le flux dpend uniquement de la porosit &nbsp;e&nbsp;.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>Le flux maximum est obtenu pour une valeur de &nbsp;e&nbsp; comprise entre 0 et 1. Il est dterminer par:<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"> </span></span><span lang=DE style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'>d</span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span></span><span lang=DE style='font-size:12.0pt;mso-bidi-font-size: 10.0pt;mso-ansi-language:DE'>SYMBOL 89 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span lang=DE style='font-size:12.0pt; mso-bidi-font-size:10.0pt;mso-ansi-language:DE'>/de= Wp [ne<sup>n</sup> (1-e) + e<sup>n</sup> (-1)]=0 <o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><span style="mso-spacerun: yes"></span><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><span style="mso-spacerun: yes"></span>do;<span style='mso-tab-count:3'> </span><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><!--[if gte vml 1]><v:rect id="_x0000_s1036"  style='position:absolute;left:0;text-align:left;margin-left:128pt;  margin-top:3.2pt;width:85.25pt;height:35.55pt;z-index:3;  mso-position-horizontal-relative:text;mso-position-vertical-relative:text'  o:allowincell="f" filled="f"/><![endif]--><![if !vml]><span style='mso-ignore: vglayout'>  <table cellpadding=0 cellspacing=0 align=left>  <tr>   <td width=171 height=4></td>  </tr>  <tr>   <td></td>   <td><img width=114 height=49 src="./chapitre2_fichiers/image002.gif" v:shapes="_x0000_s1036"></td>  </tr> </table>  </span><![endif]><span lang=DE style='font-size:12.0pt;mso-bidi-font-size:10.0pt; mso-ansi-language:DE'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <br style='mso-ignore:vglayout' clear=ALL>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><span style="mso-spacerun: yes"> </span><span style='mso-tab-count: 3'> </span>e= n/(1+n)<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><span style='mso-tab-count: 1'> </span></span><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>De la mme manire, nous pouvons dterminer la valeur de l'indice de porosit &nbsp;e&nbsp; correspondant au point d'inflexion (point critique) de la courbe </span><!--[if supportFields]><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-element:field-begin'></span>SYMBOL 89 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>= f(e)<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"> </span></span><span lang=NL style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:NL'>d</span><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-begin'></span></span><span lang=NL style='font-size:12.0pt;mso-bidi-font-size: 10.0pt;mso-ansi-language:NL'>SYMBOL 89 \f &quot;Symbol&quot;</span><![endif]--><!--[if supportFields]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-element: field-end'></span></span><![endif]--><span lang=NL style='font-size:12.0pt; mso-bidi-font-size:10.0pt;mso-ansi-language:NL'>/de = Wp [n (n-1) e<sup>n-1</sup> -n (n-1) n e<sup>n-2</sup>]=0<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=NL style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:NL'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'>dou;<span style="mso-spacerun: yes"> </span><span style="mso-spacerun: yes"></span><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><!--[if gte vml 1]><v:rect id="_x0000_s1028"  style='position:absolute;left:0;text-align:left;margin-left:128pt;  margin-top:8.45pt;width:92.35pt;height:28.45pt;z-index:2;  mso-position-horizontal-relative:text;mso-position-vertical-relative:text'  o:allowincell="f" filled="f"/><![endif]--><![if !vml]><span style='mso-ignore: vglayout'>  <table cellpadding=0 cellspacing=0 align=left>  <tr>   <td width=171 height=11></td>  </tr>  <tr>   <td></td>   <td><img width=124 height=39 src="./chapitre2_fichiers/image003.gif" v:shapes="_x0000_s1028"></td>  </tr> </table>  </span><![endif]><span lang=DE style='font-size:12.0pt;mso-bidi-font-size:10.0pt; mso-ansi-language:DE'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <br style='mso-ignore:vglayout' clear=ALL>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><span style='mso-tab-count: 4'> </span>e=(n-1)/(n+1)<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=DE style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:DE'><span style='mso-tab-count: 1'> </span></span><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>Nous avons tudi l'influence de la concentration en lments fins sur le flux solide pour des vases soutires au niveau des barrages de GHRIB, OUED EL FODDA, ZARDEZAS, IGHIL EMDA, FOUM EL GHERZA et HAMIZ. <o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Nous constatons, daprs les rsultats consigns sur la figure 36 (a  f),<span style="mso-spacerun: yes"> </span>que le flux solide suit une loi polynomiale du troisime degr en fonction de la concentration (densits) en sdiments dans la suspension, prsentant ainsi un maximum et un point dinflexion.<o:p></o:p></span></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;border:none;mso-border-top-alt: solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style="mso-spacerun: yes"> </span>La densit (concentration) de la mixture calcule par la relation de lindice de porosit<span style="mso-spacerun: yes"> </span>e = n/(1+n) = (1-c) correspondant exactement  celle du flux solide maximum, ce qui veut dire quen ce point, la dcantation des particules fines est importante et quil y aura mme risque de blocage des vannes de fond, en labsence de soutirage. <o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Par contre la densit (ou la concentration) de la mixture calcule par la relation de lindice de porosit e=(n-1)/(n+1)=1-c<span style="mso-spacerun: yes"> </span>correspond  celle du point dinflexion flux solide. Les valeurs obtenues pour les vases des six retenues tudies sont donnes dans le tableau 10.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><i style='mso-bidi-font-style:normal'><span style='font-size:8.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></i></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><i style='mso-bidi-font-style:normal'>Tableau 10.<span style="mso-spacerun: yes"> </span>Concentrations correspondantes au valeurs critiques du flux solide.<o:p></o:p></i></b></p>  <p class=MsoNormal align=center style='text-align:center'><i style='mso-bidi-font-style: normal'>(REMINI B., 1998)<o:p></o:p></i></p>  <p class=MsoNormal align=center style='text-align:center'><i style='mso-bidi-font-style: normal'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></i></p>  <table border=0 cellspacing=0 cellpadding=0 style='margin-left:3.5pt;  border-collapse:collapse;mso-padding-alt:0cm 3.5pt 0cm 3.5pt'>  <tr>   <td width=123 valign=top style='width:92.15pt;border:solid windowtext .75pt;   border-bottom:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>Vases des barrages<o:p></o:p></b></p>   </td>   <td width=161 valign=top style='width:120.5pt;border-top:solid windowtext .75pt;   border-left:none;border-bottom:none;border-right:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>Densit (ou concentration) <o:p></o:p></b></p>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>du flux maximum<o:p></o:p></b></p>   </td>   <td width=161 valign=top style='width:120.5pt;border-top:solid windowtext .75pt;   border-left:none;border-bottom:none;border-right:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>Densit (ou concentration) <o:p></o:p></b></p>   <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight:   normal'>du point<span style="mso-spacerun: yes"> </span>dinflexion<o:p></o:p></b></p>   </td>  </tr>  <tr>   <td width=123 valign=top style='width:92.15pt;border:solid windowtext .75pt;   border-right:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'>FOUM EL GHERZA</p>   <p class=MsoNormal style='text-align:justify'>GHRIB</p>   <p class=MsoNormal style='text-align:justify'><span lang=EN-GB   style='mso-ansi-language:EN-GB'>OUED EL FODDA<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=EN-GB   style='mso-ansi-language:EN-GB'>ZARDEZAS<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'>IGHIL EMDA<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'>HAMIZ<o:p></o:p></span></p>   </td>   <td width=161 valign=top style='width:120.5pt;border:solid windowtext .75pt;   border-right:none;padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 100 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 75 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span><span style="mso-spacerun:   yes"></span>C= 67 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 78,7 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span></span><span   style='font-family:Symbol;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:   "Times New Roman";mso-char-type:symbol;mso-symbol-font-family:Symbol'><span   style='mso-char-type:symbol;mso-symbol-font-family:Symbol'>r</span></span><sub><span   lang=DE style='mso-ansi-language:DE'>m</span></sub><span lang=DE   style='mso-ansi-language:DE'>= 1,030<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 110 g/l<o:p></o:p></span></p>   </td>   <td width=161 valign=top style='width:120.5pt;border:solid windowtext .75pt;   padding:0cm 3.5pt 0cm 3.5pt'>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 200 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 145 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span>C= 137 g/l<o:p></o:p></span></p>   <p class=MsoNormal style='text-align:justify'><span lang=DE style='mso-ansi-language:   DE'><span style="mso-spacerun: yes"> </span></span>C=   156 g/l</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span><span style='font-family:Symbol;mso-ascii-font-family:   "Times New Roman";mso-hansi-font-family:"Times New Roman";mso-char-type:symbol;   mso-symbol-font-family:Symbol'><span style='mso-char-type:symbol;mso-symbol-font-family:   Symbol'>r</span></span><sub>m</sub>= 1,058</p>   <p class=MsoNormal style='text-align:justify'><span style="mso-spacerun:   yes"> </span>C= 213 g/l</p>   </td>  </tr> </table>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></b></p>  <p class=MsoNormal style='text-align:justify'><span style='mso-tab-count:1'> </span><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>En comparant les valeurs des densits du tableau 10 avec celles correspondant au changement de la fonction du &nbsp;facteur de pression&nbsp; ( </span><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt;font-family:Symbol;mso-ascii-font-family:"Times New Roman"; mso-hansi-font-family:"Times New Roman";mso-char-type:symbol;mso-symbol-font-family: Symbol'><span style='mso-char-type:symbol;mso-symbol-font-family:Symbol'>D</span></span><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol; mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"; mso-char-type:symbol;mso-symbol-font-family:Symbol'><span style='mso-char-type: symbol;mso-symbol-font-family:Symbol'>r</span></span><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt'>/</span><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt;font-family:Symbol;mso-ascii-font-family:"Times New Roman"; mso-hansi-font-family:"Times New Roman";mso-char-type:symbol;mso-symbol-font-family: Symbol'><span style='mso-char-type:symbol;mso-symbol-font-family:Symbol'>r</span></span><sub><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>m</span></sub><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> </span></b><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>) donnes dans les tableaux 8 et 9, nous remarquons quelles sont identiques. Nous pouvons ainsi admettre que le point dinflexion de la fonction flux solide correspond exactement au point critique dapparition de la rigidit initiale.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Signalons enfin que DUQUENNOIS H., ds 1954<span style="mso-spacerun: yes"> </span>affirmait que la vase de la retenue dIGHIL EMDA ne se comporte plus comme un liquide Newtonien si sa densit dpasse la valeur de 1.060. Nos rsultats vont ainsi dans le mme sens, puisque la valeur critique du dbut de changement rhologique du liquide est pour nous de 1.059.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <div style='border:none;border-top:solid windowtext .75pt;padding:1.0pt 0cm 0cm 0cm'>  <p class=MsoNormal style='text-align:justify;border:none;mso-border-top-alt: solid windowtext .75pt;padding:0cm;mso-padding-alt:1.0pt 0cm 0cm 0cm'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count: 1'> </span>Allant dans le mme sens, MIGNIOT C. et VALEMBOIS J. ont tudi linfluence de la concentration en lments fins sur la rigidit de la vase de HAMIZ. La valeur de la concentration dapparition de la rigidit (240 g/l) se rapproche de la<span style="mso-spacerun: yes"> </span>notre<b style='mso-bidi-font-weight:normal'> </b>(213 g / l).<o:p></o:p></span></p>  </div>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>5. Conclusion </span></b><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family:Arial;mso-bidi-font-family: "Times New Roman"'><span style="mso-spacerun: yes"></span><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>De la prsente tude, il rsulte que:<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>-dans le cas ou le soutirage est excut pour des densits (ou concentrations) infrieures  la densit du flux maximum, une quantit de matire solide sera vacue, avec une proportion deau claire beaucoup plus leve;<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>-par contre, si le soutirage est plus excut pour des densits suprieures  celle du point dinflexion, cest  dire que les vases sont restes accumules pendant un temps assez long sous leau, leurs densits augmentent trs sensiblement. la suspension nest plus un liquide Newtonien, mais plutt plastique. La viscosit augmente aussi de telle sorte que lcoulement ne peut se faire quavec de trs fortes pertes de charges, dans ce cas une faible quantit de vase sera vacue, mais galement un faible volume deau.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span><i style='mso-bidi-font-style:normal'>Donc, nous pouvons dfinir la zone optimale de soutirage comme tant une zone comprise entre la<span style="mso-spacerun: yes"> </span>valeur de la densit du flux solide maximum et celle du point d'inflexion du flux solide.<o:p></o:p></i></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Sil est ainsi possible daffirmer que la technique du soutirage des sdiments dans les pays arides et semi arides est une ncessit, elle doit tre utilise efficacement. <o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>En effet<span style="mso-spacerun: yes"> </span>pour avoir un bon rendement au niveau du soutirage, en vacuant le maximum de vase et un minimum deau claire, nous avons montr quil existe une zone optimale de soutirage (Z.O.S), cest  dire que lvacuation des sdiments doit se faire avec des densits comprises dans cette zone.<o:p></o:p></span></p>  </div>  </body>  </html> 
