<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="./chapitre3_fichiers/filelist.xml"> <link rel=Edit-Time-Data href="./chapitre3_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>758</o:TotalTime>   <o:LastPrinted>2000-02-09T08:24:00Z</o:LastPrinted>   <o:Created>2001-02-22T14:30:00Z</o:Created>   <o:LastSaved>2001-02-22T14:30:00Z</o:LastSaved>   <o:Pages>13</o:Pages>   <o:Words>2323</o:Words>   <o:Characters>13242</o:Characters>   <o:Company> </o:Company>   <o:Bytes>99328</o:Bytes>   <o:Lines>110</o:Lines>   <o:Paragraphs>26</o:Paragraphs>   <o:CharactersWithSpaces>16262</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:""; 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ou &nbsp;Mauvais&nbsp; soutirage&nbsp;?</span></b><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'><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;text-transform: uppercase'><![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";text-transform:uppercase'>1.P</span></b><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"'>roblmatique<span style='text-transform:uppercase'><o:p></o:p></span></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>Comme nous lavons constat sur ltude prcdente, que la technique du soutirage est<span style="mso-spacerun: yes"> </span>pratique, mais mal matrise<span style="mso-spacerun: yes"> </span>sur lensemble des barrages en Algrie. Il est  rappeler 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'><span style='mso-tab-count:1'> </span>-dans certains barrages, aucune opration de soutirage na t effectue durant la priode des crues, qui est justement favorable  la formation des courants de densit;<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 dautres, des soutirages ont t oprs durant la saison sche (sans apports de crues);<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-spacerun: yes"> </span>-de nombreuses oprations de soutirage ont t pratiques au hasard, sans mme que soit mesure la<span style="mso-spacerun: yes"> </span>densit de l'eau, sauf dans la retenue du barrage dIGHIL EMDA o des rsultats trs encourageants ont t enregistres: plus de 55<b style='mso-bidi-font-weight:normal'> %</b> de la quantit des apports solides ont t soutires durant la priode 1984-1992 . <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>Ces facteurs ont conduit  des consquences dramatiques tel que: <o:p></o:p></span></p>  <p class=MsoNormal style='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>lacclration de lenvasement dans la retenue.<o:p></o:p></span></p>  <p class=MsoNormal style='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>l'obturation des pertuis de<span style="mso-spacerun: yes"> </span>vidange du barrage comme ctait le cas de OUED EL FODDA en 1948,<span style="mso-spacerun: yes"> </span>FOUM EL GHERZA en 1982 et ZARDEZAS durant les annes quatre vingt.<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>Faisant suite  ces constations, nous avons mis en vidence deux types de soutirage,  savoir un &nbsp;bon&nbsp; et un &nbsp;mauvais&nbsp; 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'><![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.<span style='text-transform: uppercase'> </span>Le<span style='text-transform:uppercase'> &nbsp;</span>Bon&nbsp; soutirage</span></b><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'>(fig. 37 a, b et c)<b style='mso-bidi-font-weight:normal'> :<o:p></o:p></b></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>A l'arrive du courant de densit au voisinage du pied du barrage, et une fois la densit de la suspension prleve est situe dans la zone optimale du soutirage, on ouvre la vanne de fond (ou la vannette de dvasement). <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>Il est  signaler que louverture de cette dernire est trs dlicate, et conduit obligatoirement soit  un dpt de sdiments (du  une faible ouverture) (fig. 38 a et b), soit  une perte d'eau claire (du  une grande ouverture) (fig. 38 a et c ). Cest pour cette raison quen dbut de lopration de soutirage, on assiste  des variations<span style="mso-spacerun: yes"> </span>de densit de la mixture. Donc aprs rglage de la vanne, il faudra un certains temps pour que la densit se stabilise et que lcoulement de la suspension devienne permanent. Une fois la stabilit de la densit de la mixture obtenue (gnralement, elle oscille entre des valeurs situes dans la zone optimale du soutirage) (fig. 39 a et b), on essaye de la maintenir le plus longtemps possible en manoeuvrant les vannes avec beaucoup de prudence jusqu ce lcoulement de la suspension devienne pratiquement<span style="mso-spacerun: yes"> </span>permanent. Dans ce cas pratiquement, tout le courant de densit sera vacu, lvolution temporelle de la vase soutire devient linaire (fig. 39 b) et la variation temporelle de la densit de la mixture devient  peu prs<span style="mso-spacerun: yes"> </span>constante (fig. 39 a).<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 &nbsp;bon&nbsp; soutirage&nbsp; dpend de deux paramtres importants : <o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><!--[if gte vml 1]><v:line id="_x0000_s1040"  style='position:absolute;left:0;text-align:left;z-index:1;  mso-position-horizontal-relative:text;mso-position-vertical-relative:text'  from="78.3pt,8.05pt" to="78.35pt,50.7pt" o:allowincell="f" strokeweight="2pt">  <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"   endarrowlength="short"/> </v:line><![endif]--><![if !vml]><span style='mso-ignore:vglayout'>  <table cellpadding=0 cellspacing=0 align=left>  <tr>   <td width=102 height=9></td>  </tr>  <tr>   <td></td>   <td><img width=5 height=62 src="./chapitre3_fichiers/image001.gif" v:shapes="_x0000_s1040"></td>  </tr> </table>  </span><![endif]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![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 style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><span style='mso-tab-count:2'> </span><span style="mso-spacerun: yes"> </span>- l'importance des dbits solides de la crue,<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:2'> </span><span style="mso-spacerun: yes"> </span>- la bonne manoeuvre des vannes. <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'><i style='mso-bidi-font-style: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Nous pouvons donc dfinir le &nbsp;bon soutirage&nbsp; comme tant un soutirage qui se pratique avec une densit de la mixture appartenant  la zone optimale du soutirage et qui (densit) sera maintenue constante (ou avec de faibles variations) pendant toute la dure de lopration.<o:p></o:p></span></i></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>La stabilit de la densit de la mixture au cours dune opration de soutirage prouve 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'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>  <p class=MsoNormal style='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>les sdiments vacues sont drains continuellement par les courants de densit dans la zone I,<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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>il ny a pas<span style="mso-spacerun: yes"> </span>de remous du courant de densit prs des vannes,<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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>lcoulement de la suspension par les pertuis de vidange est permanent.<o:p></o:p></span></p>  <p class=MsoNormal 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style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language: EN-GB'><span style='mso-tab-count:4'> </span><span style="mso-spacerun: yes"> </span>Densit<span style='mso-tab-count:3'> </span></span><b style='mso-bidi-font-weight:normal'><span lang=EN-GB style='font-size:14.0pt; mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><o:p></o:p></span></b></p>  </div>  <p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><span style='mso-tab-count:2'> </span><span style="mso-spacerun: yes"> </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><sub><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'>Y</span></span></sub><sub><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language: EN-GB'>I</span></sub><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size: 10.0pt;mso-ansi-language:EN-GB'><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><span lang=EN-GB style='font-size:14.0pt;mso-bidi-font-size:10.0pt; mso-ansi-language:EN-GB'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><span style='mso-tab-count:5'> </span>Z.O.S</span><b style='mso-bidi-font-weight:normal'><span lang=EN-GB style='font-size:14.0pt; mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"> </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><sub><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'>Y</span></span></sub><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:14.0pt;mso-bidi-font-size: 10.0pt'><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'><![if !supportEmptyParas]>&nbsp;<![endif]><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'>a) Variation de la densit<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'>de la suspension au cours</span><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'>dune opration de soutirage</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'><![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:8.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count:3'> </span><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'><span style="mso-spacerun: yes"></span>0<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'><span style='mso-tab-count:2'> </span><span style="mso-spacerun: yes"> </span>1000<span style='mso-tab-count: 4'> </span>Temps</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;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'>(heure)<span style='mso-tab-count:4'> </span><span style="mso-spacerun: yes"> </span>Vase cumule (m<sup>3</sup>)</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'><![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'><![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'><![if !supportEmptyParas]>&nbsp;<![endif]><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'>b) Evolution 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'>(cumule) soutire au cours</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'>dune opration de soutirage</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'><![if !supportEmptyParas]>&nbsp;<![endif]><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'><span style='mso-tab-count:3'> </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'><span style='mso-tab-count:3'> </span><span style="mso-spacerun: yes"> </span>0<span style='mso-tab-count:4'> </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'><span style='mso-tab-count:3'> </span><span style="mso-spacerun: yes"> </span>0<span style='mso-tab-count:4'> </span>Temps (heure)</span><b style='mso-bidi-font-weight:normal'><span style='font-size: 14.0pt;mso-bidi-font-size:10.0pt'><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'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal align=center style='text-align:center'><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 align=center style='text-align:center'><b style='mso-bidi-font-weight: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Fig. .Cas dun &nbsp;bon&nbsp; soutirage</span></b><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><![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"'><span style="mso-spacerun: yes"></span>3. Le &nbsp;Mauvais&nbsp; soutirage</span></b><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'>&nbsp;</span></b><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>(fig. 40 a, b et c)<b style='mso-bidi-font-weight:normal'><o:p></o:p></b></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>En labsence de soutirage, le courant de densit arrivant dans la zone I de la retenue, butte<span style="mso-spacerun: yes"> </span>contre le pied du barrage et revient en sens inverse jusqu' ce qu'il se stabilise (fig. 40 a). Nous sommes donc en prsence de deux couches liquides superposes de densits diffrentes (fig. 40 b). <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'>La dcantation des particules fines sera suivie d'une consolidation, ce qui<span style="mso-spacerun: yes"> </span>entranera une augmentation rapide de la densit. L'ouverture tardive de la vanne de fond (fig. 40 c) laisse vacuer une faible quantit de suspension de densit trs leve. On cre dans les dpts un entonnoir dont la forme ne dpend que du degr de consolidation, et il est absolument indpendant du dbit des vannes .<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'><i style='mso-bidi-font-style: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><span style='mso-tab-count:1'> </span>Nous dfinissons alors le &nbsp;mauvais soutirage&nbsp; comme un soutirage qui se pratique:<o:p></o:p></span></i></p>  <p class=MsoNormal style='text-align:justify'><i style='mso-bidi-font-style: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></i></p>  <p class=MsoNormal style='text-align:justify'><i style='mso-bidi-font-style: normal'><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>-avec une densit de mixture nappartenant pas  la zone optimale de soutirage (fig. 41 a et b).<o:p></o:p></span></i></p>  <p class=MsoNormal style='text-align:justify'><i style='mso-bidi-font-style: normal'><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></i></p>  <p class=MsoNormal style='text-align:justify'><i style='mso-bidi-font-style: normal'><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>-avec des variations importantes de la densit de mixture, mme si elle appartient  la zone optimale de soutirage (fig. 41 c).<o:p></o:p></span></i></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'><!--[if gte vml 1]><v:group  id="_x0000_s1041" style='position:absolute;left:0;text-align:left; 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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;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'>Y</span></span></sub><sub><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language: EN-GB'>I</span></sub><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size: 10.0pt;mso-ansi-language:EN-GB'><o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><span style='mso-tab-count:6'> </span><span style="mso-spacerun: yes"> </span>Z.O.S<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:12.0pt;mso-bidi-font-size:10.0pt;mso-ansi-language:EN-GB'><span style='mso-tab-count:4'> </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><sub><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'>Y</span></span></sub><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:14.0pt;mso-bidi-font-size: 10.0pt'><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'>a) Densits de la suspension </span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'><span style="mso-spacerun: yes"> </span>soutire au dessus de la zone </span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><span style="mso-spacerun: yes"> </span>optimale de soutirage.</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><![if !supportEmptyParas]>&nbsp;<![endif]><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'><span style='mso-tab-count:6'> </span><span style="mso-spacerun: yes"> </span>Temps (heure)<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'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><!--[if gte vml 1]><v:group id="_x0000_s1073"  style='position:absolute;left:0;text-align:left;margin-left:149.3pt; 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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;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'>Y</span></span></sub><sub><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>I</span></sub><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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-spacerun: yes"> </span><span style='mso-tab-count:7'> </span><span style="mso-spacerun: yes"></span>Z.O.S</span><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><o:p></o:p></span></b></p>  <p class=MsoNormal style='text-align:justify'><span style='font-size:12.0pt; 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mso-bidi-font-size:10.0pt'>densit de la suspension<span style="mso-spacerun: yes"> </span>soutire.</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><![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'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></b></p>  <p class=MsoNormal style='text-align:justify'><!--[if gte vml 1]><v:group id="_x0000_s1086"  style='position:absolute;left:0;text-align:left;margin-left:149.3pt;  margin-top:25.85pt;width:191.75pt;height:128.85pt;z-index:5' coordorigin="46"  coordsize="19175,20000" o:allowincell="f">  <v:line id="_x0000_s1087" style='position:absolute' from="1111,0" to="1116,20000">   <v:stroke startarrow="block" startarrowwidth="narrow" startarrowlength="short"    endarrowwidth="narrow" endarrowlength="short"/>  </v:line><v:line id="_x0000_s1088" style='position:absolute;flip:x' from="46,18518"   to="18686,18525">   <v:stroke startarrow="block" startarrowwidth="narrow" startarrowlength="short"    endarrowwidth="narrow" endarrowlength="short"/>  </v:line><v:line id="_x0000_s1089" style='position:absolute' from="46,3702"   to="19221,3710" strokeweight=".5pt">   <v:stroke dashstyle="1 1" startarrowwidth="narrow" startarrowlength="short"    endarrowwidth="narrow" endarrowlength="short"/>  </v:line><v:line id="_x0000_s1090" style='position:absolute' from="46,8886"   to="19221,8894" strokeweight=".5pt">   <v:stroke dashstyle="1 1" startarrowwidth="narrow" startarrowlength="short"    endarrowwidth="narrow" endarrowlength="short"/>  </v:line><v:line id="_x0000_s1091" style='position:absolute' from="1111,9624"   to="2711,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1092" style='position:absolute;flip:y' from="2711,9624"   to="4311,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1093" style='position:absolute' from="4311,9624"   to="5381,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1094" style='position:absolute;flip:y' from="5371,9624"   to="6971,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1095" style='position:absolute' from="6966,9624"   to="8036,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1096" style='position:absolute;flip:y' from="8031,9624"   to="9631,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1097" style='position:absolute' from="9631,9624"   to="10701,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1098" style='position:absolute' from="10696,10376"   to="12826,10384" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1099" style='position:absolute;flip:y' from="12831,9624"   to="13901,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1100" style='position:absolute' from="13896,9624"   to="14431,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1101" style='position:absolute;flip:y' from="14421,9624"   to="14956,10369" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line><v:line id="_x0000_s1102" style='position:absolute' from="14956,9624"   to="18156,18510" strokeweight="1pt">   <v:stroke startarrowwidth="narrow" startarrowlength="short" endarrowwidth="narrow"    endarrowlength="short"/>  </v:line></v:group><![endif]--><![if !vml]><span style='mso-ignore:vglayout; position:absolute;z-index:46;left:0px;margin-left:198px;margin-top:33px; width:259px;height:175px'><img width=259 height=175 src="./chapitre3_fichiers/image005.gif" v:shapes="_x0000_s1086 _x0000_s1087 _x0000_s1088 _x0000_s1089 _x0000_s1090 _x0000_s1091 _x0000_s1092 _x0000_s1093 _x0000_s1094 _x0000_s1095 _x0000_s1096 _x0000_s1097 _x0000_s1098 _x0000_s1099 _x0000_s1100 _x0000_s1101 _x0000_s1102"></span><![endif]><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><span style='mso-tab-count:6'> </span><span style="mso-spacerun: yes"> </span><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"></span></span></b><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>Temps (heure)</span><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><span style='mso-tab-count:4'> </span><span style="mso-spacerun: yes"> </span></span></b><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>Densit</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><span style='mso-tab-count:3'> </span><span style="mso-spacerun: yes"> </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><sub><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'>Y</span></span></sub><sub><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>I</span></sub><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'><![if !supportEmptyParas]>&nbsp;<![endif]><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'><span style='mso-tab-count:7'> </span>Z.O.S</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'><span style='mso-tab-count:3'> </span><span style="mso-spacerun: yes"> </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><sub><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'>Y</span></span></sub><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:14.0pt;mso-bidi-font-size: 10.0pt'><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'>c) Densits de la suspension</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'>soutire au dessous de la zone</span><b style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt;mso-bidi-font-size: 10.0pt'><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'>optimale de soutirage.<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'><![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'><span style='mso-tab-count:6'> </span><span style="mso-spacerun: yes"> </span><span style='mso-tab-count:1'> </span><span style="mso-spacerun: yes"></span></span></b><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'>Temps (heure)</span><b style='mso-bidi-font-weight: normal'><span style='font-size:14.0pt;mso-bidi-font-size:10.0pt'><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'><![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'><span style='mso-tab-count:2'> </span></span></b><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>Fig. . Cas dun &nbsp;mauvais&nbsp; soutirage<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'><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"'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></b></p>  <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'><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. Quelques exemples de types de soutirages pratiqus au niveau des barrages Algriens<u><o:p></o:p></u></span></b></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'><span style='mso-tab-count:1'> </span>Afin de mieux mettre en lumire et diffrencier les diffrents types de soutirages, nous avons trait des exemples d oprations de soutirages effectues dans les retenues des barrages dIGHIL EMDA, ERRAGUENE et KSOB .<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:12.0pt;mso-bidi-font-size:10.0pt;font-family: Arial;mso-bidi-font-family:"Times New Roman"'>a) <u>Barrage dIGHIL EMDA<o:p></o:p></u></span></b></p>  <p class=MsoNormal style='text-align:justify'><b style='mso-bidi-font-weight: normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></u></b></p>  <p class=MsoNormal style='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 9 au 15 Dcembre 1965</span></u></b><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'>(fig. 42)<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>Une crue est survenue<span style="mso-spacerun: yes"> </span>du 9 au 15 dcembre provoquant un dbit solide important, qui a conduit  la formation dun courant de densit dans la retenue. Le soutirage du courant a dur exactement 148 heures sans arrt avec une densit variant de 1,060  1,079 (situe  lextrieures de la zone optimale de Soutirage) (fig. 42).<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'>La mixture soutire ne se comporte plus comme liquide Newtonien mais plutt Bingham. La quantit de vase vacue est de 864. 10<sup>6</sup> m<sup>3</sup> avec un volume deau claire gale  6,6.10<sup>6</sup> m<sup>3</sup> soit un rapport de 13 % quivalent  1 litre de vase pour 7,6 litres deau. Ce cas peut tre class comme &nbsp;mauvais&nbsp;&nbsp; soutirage.<o:p></o:p></span></p>  <p class=MsoNormal style='text-align:justify'><u><span style='font-size:12.0pt; mso-bidi-font-size:10.0pt'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></u></p>  <p class=MsoNormal style='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 22 au 25 dcembre 1966</span></u></b><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'>(fig. 43)<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>La crue survenue du 22 au 25 dcembre 1966 dans la retenue dIGHIL EMDA a donn&nbsp; naissance  un courant de densit. Daprs la figure 43 a, reprsentant la variation de la densit en fonction du temps, la densit de la mixture prleve le 22 dcembre 1966  10 heures tait de 1,0405, ce qui justifie larrive du courant de densit dans la zone basse (prs des vannes). <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'>Aussitt, la vanne a t ouverte et lopration de soutirage a dure environ 63 heures avec une densit de la suspension<span style="mso-spacerun: yes"> </span>variant entre 1,040 et 1,055, ce qui a donn un volume de vase gal  55.10<sup>3</sup><span style="mso-spacerun: yes"> </span>m<sup>3</sup> pour une proportion deau gale  662 10<sup>3</sup> m<sup>3</sup>,<span style="mso-spacerun: yes"> </span>soit un rapport de 8,3 % (quivalent  1 litre de vase pour 12 litres deau). Ce soutirage peut tre class comme &nbsp;bon&nbsp; soutirage puisque la densit de la suspension a t grade presque constante dans la zone optimale du soutirage (1,030&lt; densit &lt; 1,060) durant plus de 60 heures, et que lvolution de la quantit de vase (cumule) vacue est presque linaire dans le temps (fig. 43 b).<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='margin-top:0cm;margin-right:14.2pt;margin-bottom: 0cm;margin-left:14.15pt;margin-bottom:.0001pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 18 Octobre 1983</span></u></b><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'> (fig. 44 (a et b)<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>La crue du 18 Octobre a donn &nbsp;naissance&nbsp;  un courant de densit. Le soutirage de ce dernier a dur environ 20 heures avec une densit variante de 1,025  1,036 (plus ou moins dans la zone optimale de soutirage) ce qui a donn un volume de vase vacu gal  14.10<sup>6</sup> m<sup>3</sup> pour une proportion deau gale  316.10<sup>6</sup> m<sup>3</sup>, soit un rapport de 4,4 %, ce qui est quivalent  1 litre de vase pour 22 litres deau 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'><span style='mso-tab-count:1'> </span>La stabilit de la densit de la mixture (fig. 44 a) qui a engendr une volution<span style="mso-spacerun: yes"> </span>presque linaire du volume de vase (cumul) en fonction du temps (fig. 44 b), prouve que le soutirage a t bien pratiqu. Nanmoins, il faut noter que le courant a une faible densit. Ce cas peut tre class comme &nbsp;bon soutirage&nbsp;.<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'><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"'>b) <u>Barrage dERRAGUENE</u></span></b><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"'> <o:p></o:p></span></b></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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 01 au 08 Dcembre 1969</span></u></b><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'>(fig. 45 ( a et b))<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>La crue a dur exactement 08 jours par contre, on assiste  trois soutirages :<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 premier qui a t excut et a dur 72 heures sans interruption du 01 dcembre  16 h au 04 dcembre  16h. La densit de la mixture est reste dans lintervalle 1,045 - 1,056 pendant plus de 52 heures (fig. 45 a), ce qui confirme que le soutirage a t bien excut. Le graphe du volume de vase cumule en fonction du temps est une droite linaire (fig. 45 b). Ce cas peut tre considr comme &nbsp;bon&nbsp; 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>Le courant de densit a t compltement puis le 4 dcembre 1969  16 heures. Les vannes tant fermes, mais, on contrle toujours la densit de leau. La rouverture de la vanne a eu lieu le 05 dcembre  10 heures. Le soutirage a dur environ 10 heures et la densit de la suspension na pas dpasse 1,025. Aprs trois jours de fermeture des vannes, une densit de 1,065 a t mesure le 8 dcembre  8 heures. Aussitt, la vanne a t ouverte et la densit a chut en 4 heures pour atteindre 1,000. Nous pensons que ce dernier cas, peut tre soit un courant de densit de faible intensit, soit  une rosion des derniers dpts de vases dans la zone basse<span style="mso-spacerun: yes"> </span>non encore consolids.<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>Un volume total de vase gal  18,4. 10<sup>3</sup> m<sup>3</sup> a t vacu avec une proportion deau gale  2,6. 10<sup>6</sup> m<sup>3</sup>. Soit un rapport de 7%. Un volume gal  29. 10<sup>6</sup> m<sup>3</sup> deau a t apport par la crue, soit un rapport de 1/10 entre leau perdue et lapport.<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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 25 au 28 Septembre 1973</span></u></b><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> (fig. 46)<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>La crue du 25 au 28 Septembre 1973 a donn naissance  un courant de densit qui a drain des sdiments dont la concentration est 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'><![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>Louverture des vannes a eu lieu le 25 Septembre  6 heures aprs avoir dtect une densit de leau turbide gale  1,030. le soutirage<span style="mso-spacerun: yes"> </span>a dur plus de 76 heures durant lesquelles, la densit de la mixture est reste constante gale  1,060 pendant 16 heures et 1,045 durant 28 heures (fig. 46) ce qui explique bien que les vannes ont t bien manoeuvres et le courant de densit a t bien soutir. Ce cas peut etre un &nbsp;bon&nbsp; soutirage&nbsp;.<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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 24 au 25 Aot 1981</span></u></b><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'> (fig. 47 ( a et b))<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>Lopration du soutirage a dur environ 16 heures ( soit du 24 aot  15 heures au 25 aot  7 heures), avec des densits de la suspension vacue trs<span style="mso-spacerun: yes"> </span>variables dans le temps (presque chaque heure)<span style="mso-spacerun: yes"> </span>allant de 1,020  1,040 (fig. 47 a), ce qui a pu favoriser le dpt, et en mme temps une perte deau considrable. Il en est rsulte une variabilit de dbit des sdiments, ce qui a conduit  une volution non linaire de la vase (cumule) soutire (fig. 47 b). Ce type de soutirage peut etre considr comme &nbsp;mauvais soutirage&nbsp;. Le volume de vase vacu est gal  28.10<sup>3</sup> m<sup>3</sup><span style="mso-spacerun: yes"> </span>pour une quantit deau<span style="mso-spacerun: yes"> </span>5  6 fois suprieure.<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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 15 au 18 Novembre 1990</span></u></b><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> (fig. 48)<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>Durant cette cure, le soutirage du courant de densit<span style="mso-spacerun: yes"> </span>a dur 72 heures, sans interruption et durant plus de 48 heures, la mixture a gard une densit variable entre 1,035 et 1,055 (fig. 48) qui est comprise dans la zone optimale de soutirage. Lcoulement de la couche turbide est presque permanent avec videmment absence de remous prs des vannes. <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'>Lensemble des sdiments drains par ce courant ont t soutirs. Les manoeuvres des vannes ont t bien excutes do lobtention dun &nbsp;bon&nbsp;&nbsp;soutirage.<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;font-family: Arial;mso-bidi-font-family:"Times New Roman"'><![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'><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"'>c) <u>Barrage de KSOB</u><o:p></o:p></span></b></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='margin-left:14.15pt;text-align:justify;text-indent: -14.15pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size: 12.0pt;mso-bidi-font-size:10.0pt;font-family:Symbol'><span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><![endif]><b style='mso-bidi-font-weight:normal'><u><span style='font-size:12.0pt;mso-bidi-font-size:10.0pt'>Soutirage du 01 au 02 Octobre 1985</span></u></b><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt'> (fig. 49 )<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>Le soutirage a dur environ 31 heures sans arrt, et la vanne de fond a t ouverte le premier octobre  15 heures, aprs prlvement dune densit de la mixture gale  1,250, valeur qui laisse supposer<span style="mso-spacerun: yes"> </span>que le courant de densit est arriv dans la zone<span style="mso-spacerun: yes"> </span>basse<span style="mso-spacerun: yes"> </span>de la retenue bien avant 15 heures, puisque cette forte valeur est obtenue  la suite dune dcantation rapide des particules fines draines par les courants de densit acclre par<span style="mso-spacerun: yes"> </span>la fermeture de la vanne de fond pendant un temps assez long. <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>Durant les trois premires heures du soutirage, la densit de la mixture a chut de 1,250  1,120 pour ensuite se maintenir entre 1,050 et 1,100 durant environ 21 heures. La vanne a t ferme le 02 Octobre  21 heure (fig. 49). Le soutirage a t ffectu pour des concentrations nettement superieure  celle situe dans la &nbsp;zone optimale du soutirage&nbsp;, le fluide nest plus newtonnien mais plutot binghamien. Ce cas peut etre class comme &nbsp;mauvais&nbsp; soutirage. Durant cette opration, un volume de 47. 10<sup>3</sup> m<sup>3</sup> de vase a t soutir. <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"'>5. Propositions pratiques pour<span style="mso-spacerun: yes"> </span>un &nbsp;bon&nbsp;&nbsp; soutirage</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"'> </span></b><span style='font-size:12.0pt;mso-bidi-font-size: 10.0pt;font-family:Arial;mso-bidi-font-family:"Times New Roman"'>( fig. 50)<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>Ds l'arrive dune crue dans la retenue dun barrage, on commence  faire des mesures de densit de leau (prs des vannes) par la prise systmatique dchantillons (avec une bouteille) ou par lemploi dun appareillage spcial constitu par un ensemble de tubes de faible diamtre (fig. ) qui dtermine limportance de la distribution verticale des densits des matires solides aux abords de la prise deau. A notre connaissance, les barrages d'IGHIL EMDA et d'ERRAGUENE sont les seuls  tre quips dun tel appareillage.<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>Ds que la densit se rapproche de celle de la zone optimale du soutirage (par exemple, pour le barrage dIGHIL EMDA, DUQUENNOIS H. a propos la valeur de 1,020 qui est infrieure  la valeur minimale (1,030) de la zone optimale du soutirage), on ouvre une vannette (ou la vanne de fond <span style="mso-spacerun: yes"> </span>1/4 pour les barrages non quips dun dispositif de soutirage) pour amorcer l'coulement des couches infrieures et viter le remous du courant de densit et l'accumulation de vase concentre devant les vannes, ce qui rendrait par la suite plus difficile le rglage du dbit.<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>On mesure toute les heures ( ventuellement toutes les<span style="mso-spacerun: yes"> </span>deux heures) la densit de la suspension soutire; tant qu'elle ne dpasse pas la valeur de la densit correspondant  l'apparition de la rigidit initiale de la suspension ( tableau 29), il n'ya pas lieu d'ouvrir d'autres vannettes (ou bien d'ouvrir<span style="mso-spacerun: yes"> </span>la vanne de fond  1/2 ou plus). Il est  noter que DUQUENNOIS H.<span style="mso-spacerun: yes"> </span>a propos pour le cas d'IGHIL EMDA l'intervalle de densit 1,040-1,050. Si au contraire, la densit dpasse cette valeur du point dinflexion du flux solide, on ouvre dautres vannettes (ou la vanne de fond  1/2 ou 3/4) jusqu ce que la densit se stabilise  une valeur de la zone optimale du soutirage. Puis, on essaye de garder le plus longtemps possible lcoulement 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'><![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>Enfin ds que la densit commence  diminuer, on ferme les vannettes une par une (ou progressivement la vanne de fond) et on arrte les oprations lorsque la densit tombe  des valeurs infrieures  celle du flux solide maximum, mais on continue  faire des mesure de la densit jusqu la fin de la crue.<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>Il est  noter que les variations de densit sont assez lentes et des manoeuvres de vannes trop<span style="mso-spacerun: yes"> </span>rapproches risquent de donner des rsultats trs divergents.<span style="mso-spacerun: yes"> </span>Selon DUQUENNOIS H.: &nbsp;la manoeuvre d'une vannette par heure suffit gnralement  rgler correctement la densit&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'><span style='mso-tab-count:1'> </span>Lorsqu'il ne reste plus qu'une vannette ouverte et que la densit descend au dessous de celle du flux solide maximum, il est prfrable de laisser ouverte cette vannette (ou la vanne de fond ouverte  <b style='mso-bidi-font-weight:normal'>1/4</b>) jusqu' une valeur beaucoup plus faible (<b style='mso-bidi-font-weight:normal'>1,020</b> par exemple) pour sassurer que le courant de densit soit compltement soutir. Une ouverture de courte dure pourra se faire aprs quelques heures de la fin de lopration.<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'><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"'>6. Conclusion<o:p></o:p></span></b></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'><span style='mso-tab-count:1'> </span>Nous distinguons deux types de soutirages: les &nbsp;bon&nbsp; et &nbsp;mauvais&nbsp; soutirages montrent chacun des diffrences dans la densit de la suspension soutire, ce qui a pour consquence une influence sur le rgime (permanent ou non permanent) de lcoulement de la suspension  travers les pertuis de vidange.<o:p></o:p></span></p>  </div>  </body>  </html> 
