[文章]：后张预应力箱梁监理过程中应控制的要点

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后张预应力箱梁监理过程中应控制的要点


<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体; mso-bidi-font-weight: bold">关键词：预应力、箱梁、管道、定位、钢绞线、伸长值、弹性模量、设计、张拉。<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>   
<P class=MsoBodyTextIndent style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 28pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">序：预应力砼箱梁具有比普通钢筋砼桥梁优良的使用性能，提高了耐疲劳强度，充分利用了高强度钢材，但是对施工则提出了更高的要求：需要严格的施工作业程序，需要有较高技能的技术工人、特殊精密的施工测量设备以及高质量的材料。随着预应力混凝土桥梁在我国公路建设中被广泛采用，虽然随着社会科学技术水平的提高，施工技术水平也越来越高，但还是有一些问题经常出现，现就施工中经常发生的问题做一探讨。<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: -36pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-list: l1 level1 lfo2; tab-stops: list 36.0pt"><B><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体; mso-bidi-font-family: 仿宋_GB2312"><SPAN style="mso-list: Ignore">一、<SPAN style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </SPAN></SPAN></SPAN></B><B><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">管道敷设<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></B></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 28pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 2.0"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">后张预应力施工时，人们的注意力容易集中在预应力的施加阶段，如张拉顺序、张拉力大小与伸长量的比例关系等，但应该清醒地认识到管理成型阶段的重要性。预应力管道施工的成功在于预应力管道的位置和大小的准确，管道成型阶段的重要性在于不仅它决定了最终预应力的位置，而且对于最终预应力的大小有重要的影响，例如管道漏浆可能导致预应力损失增大而局部预应力不足。<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 28pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 2.0"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">预应力管道施工常遇到的通病有：定位不准、管道位置不牢、管道漏浆、预埋锚垫板。<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><B><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">1、定位不准确<o:p></o:p></SPAN></B></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp; </SPAN>一般用管道某点至模板的相对位置定位，从模板底向上测量确定高程，以模板端头的位置确定水平纵模坐标。施工过程中严格控制管道坐标的方法是将每根管道定位数据复核后列表，经批准后用于施工操作和施工检查。有时候预应力管道和钢筋位置的冲突，可能导致预应力管道“让位”于普通钢筋。这是错误的。正确操作方法是让钢筋给管道“让位”，保证管道坐标曲线位置的正确，符合表－1规定偏差。预应力结构中，预应力筋的位置比普通筋的远为重要。<o:p></o:p></SPAN></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><B><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">2、管道位置不牢<o:p></o:p></SPAN></B></P>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 28pt; mso-char-indent-count: 2.0"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">尽管施工时要采取措施尽量避免砼灌入和振捣时的冲击，但管道的牢固必须能够抵抗这种冲击。否则预应力管道会发生移位，有时甚至很严重。单放波纹管而不穿入钢束时，应考虑抵抗浮力。避免方法：选择优质预应力管道，适当缩短固定环的间距，严格遵守规范规定（直线段间距<SPAN lang=EN-US>1.0米，曲线段间距0.5米。）<SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN></SPAN><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312"><o:p></o:p></SPAN></P>   
<P class=MsoNormal style="MARGIN: 0cm 21pt 0pt 0cm; TEXT-INDENT: 350pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 25.0"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">表－<SPAN lang=EN-US>1<o:p></o:p></SPAN></SPAN></P>   
<TABLE class=MsoNormalTable style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; MARGIN: auto auto auto 5.4pt; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; mso-table-layout-alt: fixed; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext" cellSpacing=0 cellPadding=0 border=1>   
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<TR style="HEIGHT: 16pt; mso-yfti-irow: 0">   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 42pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 16pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt" vAlign=top width=56>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">项次<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 210pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 16pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=280 colSpan=2>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">检查项目<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 162pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 16pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=216>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">允许偏差值（<SPAN lang=EN-US>mm）<o:p></o:p></SPAN></SPAN></P></TD></TR>   
<TR style="HEIGHT: 21pt; mso-yfti-irow: 1; page-break-inside: avoid">   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 42pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 21pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=56 rowSpan=2>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">1<o:p></o:p></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 99.75pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 21pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=133 rowSpan=2>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">管道坐标<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 110.25pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 21pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=147>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">水平向<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 162pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 21pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=216>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">30<o:p></o:p></SPAN></P></TD></TR>   
<TR style="HEIGHT: 20pt; mso-yfti-irow: 2; page-break-inside: avoid">   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 110.25pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 20pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=147>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">竖向<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 162pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 20pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=216>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">10<o:p></o:p></SPAN></P></TD></TR>   
<TR style="HEIGHT: 19pt; mso-yfti-irow: 3; page-break-inside: avoid">   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 42pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 19pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=56 rowSpan=2>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">2<o:p></o:p></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 99.75pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 19pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=133 rowSpan=2>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">管道间距<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 110.25pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 19pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=147>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">同排<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 162pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 19pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=216>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">10<o:p></o:p></SPAN></P></TD></TR>   
<TR style="HEIGHT: 22pt; mso-yfti-irow: 4; page-break-inside: avoid; mso-yfti-lastrow: yes">   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 110.25pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 22pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=147>   
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">上下层<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>   
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 162pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 22pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=216>   
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3、管道漏浆

在浇筑混凝土时，施工中对管道的碰撞和挤压是不可避免的。碰撞造成管道破损，导致漏浆。管道接头处理不当亦是漏浆的原因。由于钢筋结构复杂，直径小于1cm的漏洞不易被检查出来，尤其是管道的阴面。漏浆会导致穿束困难或预应力损失增加，严重的情况是使用联接器的长束在漏浆处被锚固，使局部预应力为零，而问题直到张拉时才被发现。防止漏浆的唯一办法是在浇筑之前由专门人员仔细检查。对于两端张拉的预应力筋，补救办法是在正式张拉前单向拉动预应力筋，如有漏浆即可发现。

4、预埋锚垫板

预埋钢垫板通常是被固定在端模板上的，但其轴线往往与钢绞线端部的轴线不一致，这种问题在工地上常常遇到。加工端模时，据设计准确计算出锚垫板上下端水平误差，逐个检查，保证锚垫板与钢绞线轴线垂直。

二、   张拉

施工中人们已经普遍注意千斤顶和压力表配套的标定工作，但其他一些细节常被忽视。

1、千斤顶轴线与预应力筋轴线不一致

    千斤顶轴线与预应力筋轴线不一致时出现的情形—锚板背面与千斤顶支脚端面形成夹角，千斤顶给油时处于下缘的钢丝束先受力，而上缘的钢丝束直到缝隙闭合才会受力，使得同一束内各根钢绞线的张拉力不均匀。当分级张拉时，如此重复几次，就会导致很大的误差积累。另外千斤顶开始给油前，工具锚上的夹片未被顶紧或被顶紧的程度不一，也会产生类似的结果。

2、弹性模量的影响

   钢绞线的理论伸长值应按照规范规定的计算公式来计算。对于钢绞线，应使用其实际的弹性模量值。国外和我国的预应力钢绞线产品标准对弹性模量的要求为195±10GPa。规范要求“实际值与理论伸长值得差值应控制在6%以内”，可见，若取钢绞线的理论弹性模量值（195GPa）,仅钢绞线实际弹性模量变化的影响已接近施工规范的要求值，再加上其他施工误差的影响，伸长值控制必定超出规范要求值。另外，气温队伸长值影响也较大，金水东路互通式立交桥箱梁张拉过程中发现夏季施工太阳直射面伸长是远远超过6%而背面符合要求，所以，我们规定张拉时间为上午5-10点之间。

3、张拉顺序

设计通常会给出张拉顺序或张拉先后原则，具体每次张拉哪一

束仍学做出明确的安排，而且应获得批准，这是避免张拉过程中出现局部应力过大的有效措施。

4、理论伸长值与实测伸长值差值较大的原因有：

（1）     锚固端松弛，伸长值增大；

（2）     预应力筋在混凝土浇筑之前放入管道，如果管道漏浆会造成预应力损失偏大，造成实测伸长量偏小；

（3）     管道固定不牢固，管道变形，位置不准，预应力损失过大或者过小；

（4）     计算理论伸长量时，未按实际的预应力筋弹性模量计算而造成的误差；

（5）     预应力筋截面面积的偏差可能导致理论伸长计算误差；

（6）     千斤顶和压力表配套使用时间较长或发生意外造成测定拉力不准，此时应及时标定。

表－2列出了后张法施工时应检查的项目，供施工时参考。

<table>
  <TBODY>
<TR style="HEIGHT: 16pt; mso-yfti-irow: 0">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 70.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 16pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt" vAlign=top width=94>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 7.5pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">阶 段<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 351pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 16pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=468>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 7.5pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">检<SPAN lang=EN-US><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>查<SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>内<SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>容<o:p></o:p></SPAN></SPAN></P></TD></TR>
<TR style="HEIGHT: 60pt; mso-yfti-irow: 1">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 70.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 60pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=94>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">材料<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">制造<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 351pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 60pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=468>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">锚头的清洁、防锈保护是否恰当<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">夹片、螺母的防锈保护是否恰当<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">管道是否用合格的钢材制成，是否具有足够的刚度<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">预应力钢材储存、保护是否防锈、防污染<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD></TR>
<TR style="HEIGHT: 78pt; mso-yfti-irow: 2">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 70.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 78pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=94>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">预应力管道及预力筋安装<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 351pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 78pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=468>
<p align=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">管道中心的高点和低点是否在正确的高度上<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">管道的外形是否平滑，参考点之间的形状（抛物线、圆曲线、直线）是否正确<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">管道是否有变形，是否妨碍预应力筋变位<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">承压板是否固定在模板上，位置及斜度是否准确，螺纹钢筋是否符合要求<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">如果浇筑砼须注意某些事项，是否已落实<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></a></b></TD></TR>
<TR style="HEIGHT: 78pt; mso-yfti-irow: 3; mso-yfti-lastrow: yes">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 70.5pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 78pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=94>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">预应力<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">张拉<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #ece9d8; WIDTH: 351pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 78pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=468>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">锚头、夹片和螺母有无锈蚀，是否合适、清楚<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-pagination: widow-orphan" align=left><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">伸长值测量的初终读数的标志是否合适、清楚<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">张拉设备的保养是否良好，标志是否有效<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">使用设备是否符合操作规程<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">张拉后夹片、垫片、螺母的固定是否正确<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">封锚是否适当<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P></TD></TR></TBODY></TABLE>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><B style="mso-bidi-font-weight: normal"><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">5、</SPAN></B><B><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">测量伸长值的方法<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></B></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp; </SPAN><SPAN style="mso-spacerun: yes">&nbsp;</SPAN></SPAN><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">对于钢束实际伸长值的测量，建议应用量测预应力筋绝对伸长值的方法，而不能使用量测千斤顶活塞伸出量的方法，后者测得的伸长值需考虑工具锚、工作锚处钢束回缩的影响，尤其在分级张拉时，比较繁琐，否则偏差很大。使用正确简便的测量方法，如：使用一个标尺固定在两根相邻的钢绞线上，不论经过几个行程均以次来量测分级张拉的伸长量，累计的结果即为初应力与终应力之间的实测伸长值。<B style="mso-bidi-font-weight: normal">三、<SPAN style="mso-bidi-font-weight: bold">设计的问题</SPAN></B><SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.5"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">预应力施工不仅对施工技术提出了较高的要求，同时有些问题实在设计时容易被忽视的。如果平弯桥的弯曲半径小于<SPAN lang=EN-US>170米，腹板内的水平弧形纵向束张拉时产生的径向力可能导致超过腹板钢筋混凝土的承受能力，导致混凝土破坏。<o:p></o:p></SPAN></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 28pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 2.0"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312; mso-hansi-font-family: 宋体">再如，锚块处弯曲的预应力筋径向力很大，而如果不配有足够的箍筋可能导致混凝土被崩开，同时锚块与非预应力区交界处可能由于配筋的不足而导致在混凝土浇筑后即发生收缩开裂，或者张拉预应力后开裂。<SPAN lang=EN-US>45度箱梁端头处出现“三角”地带图纸未绘出配筋图，这就需要增加箍筋且沉“三角”布置，另外，锚垫板内侧人为增加双向网片。还有要重视端头板砼振捣和养生。<o:p></o:p></SPAN></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.5"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">还有大跨连续梁梁底竖向弧形曲线预应力钢束导致的开裂。由于底板内预应力束过密（中距小于<SPAN lang=EN-US>20cm），而且布置在底板横向的跨中,底板横向抗弯度小于弯曲预应力束产生的弯矩使得底板纵向开裂。<o:p></o:p></SPAN></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 28pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly; mso-char-indent-count: 2.0"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">对以上这些问题，审图时要多加注意，必要时在设计交底时提出，避免施工时发生意外，造成不可挽回的损失。<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312"><o:p>&nbsp;</o:p></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN lang=EN-US style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312"><o:p>&nbsp;</o:p></SPAN></P>        
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 23pt; mso-line-height-rule: exactly"><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: 仿宋_GB2312">参考文献：<SPAN lang=EN-US><SPAN style="mso-spacerun: yes">&nbsp; </SPAN>公路桥涵施工技术规范<SPAN style="mso-spacerun: yes">&nbsp;&nbsp; </SPAN>（JTJ041－2000）<o:p></o:p></SPAN></SPAN></P>        
<table>