不同轴压下悬挂式防渗墙堤基渗透坡降试验
水利水电科技进展,2016,36(3)一Tel :025********一E-mail :jz @https://www.wendangku.net/doc/e711719665.html, 一http ://https://www.wendangku.net/doc/e711719665.html,
第36卷第3期Vol.36No.3水利水电科技进展
Advances in Science and Technology of Water Resources
2016年5月May 2016
基金项目:国家自然科学基金(51579078,51474204)
作者简介:詹美礼(1959 ),男,教授,主要从事渗流力学二地下水污染及控制技术研究三E-mail:zhanmeili@https://www.wendangku.net/doc/e711719665.html,
DOI:10.3880/j.issn.10067647.2016.03.008
不同轴压下悬挂式防渗墙堤基渗透坡降试验
詹美礼1,闫一萍1,尹江珊1,唐一健1,踪金梁2,盛金昌1,罗玉龙1
(1.河海大学水利水电学院,江苏南京一210098;2.江苏省设备成套有限公司,江苏南京一210009)
摘要:为了研究含悬挂式防渗墙的强透水堤坝坝基在不同轴压状态下的渗透特性,分别开展了3种不同高度防渗墙在不同轴向应力状态下的渗流应力耦合管涌试验三结果表明:防渗墙端部位置渗透流速较大,更易发生渗透破坏;坝基平均渗透坡降随防渗墙高度增加而减小,防渗墙渗流轮廓线上,防渗墙端部的渗流梯度最大,应力状态对悬挂式防渗墙砂砾石地基渗透坡降影响显著,管涌临界渗透坡降与轴压呈抛物线关系,防渗墙端部的渗透破坏坡降随轴压增大而线性增大三在此基础上,建立了用轴压表示的防渗墙端部渗透破坏坡降线性经验公式三关键词:堤基;防渗墙;渗透破坏;出砂量;渗透坡降
中图分类号:TV139.16一一一文献标志码:A一一一文章编号:10067647(2016)03003605
Experimental study on seepage gradient of embankment foundations with suspended cut-off walls under different axial pressures //ZHAN Meili 1,YAN Ping 1,YIN Jiangshan 1,TANG Jian 1,ZONG Jinliang 2,SHENG Jinchang 1,LUO Yulong 1(1.College of Water Conservancy and Hydropower Engineering ,Hohai University ,Nanjing 210098,China ;2.Jiangsu Complete Equipment Co.,Ltd.,Nanjing 210009,China )
Abstract :In order to study the permeability of highly permeable embankment foundations with suspended cut-off walls,a series of seepage-stress coupling experiments with cut-off walls of three different heights in different axial stress states were carried out.Results show that seepage failure is more likely to occur at the bottom of cut-off walls because of high seepage velocity there,the average seepage gradient of the embankment foundation decreases with the increase of the height of cut-off walls,and the seepage gradient at the bottom of cut-off walls is always maximum along the seepage contour line.Stress states have large effects on the seepage gradient of sand gravel foundations with suspended cut-off walls.There is a parabolic relationship between critical seepage gradient of piping and axial pressure.The seepage gradient causing seepage failure at the bottom of cut-off walls increases linearly with the increase in axial pressure.Based on these results,a linear empirical formula for the seepage gradient causing seepage failure at the bottom of cut-off walls,denoted by the axial pressure,is established.
Key words :embankment foundation;seepage failure;cut-off wall;amount of sand production;seepage gradient
一一在水利工程中,堤基的渗透变形严重影响着堤防工程的稳定性和大坝的安全运行,这其中又以管涌破坏形式最为常见[1-4]三对堤基渗透破坏及防渗处理的研究一直是个重要的课题三毛昶熙等[5]通过试验研究提出了堤基渗流的无害管涌概念,认为管涌有害与否与沿程承压水头分布的不断调整和渗流量变化密切相关三刘杰等[6-7]将复杂的堤基归纳概化为3种类型,分别进行了模拟试验,指出砂基的抗渗强度主要决定于砂土本身的抗渗强度,并对堤基砂砾石层的管涌破坏危害性进行了试验研究,指出在发生管涌破坏后,土骨架的结构不会产生明显变化,但渗透系数会显著增大三陈建生等[8]利用室内试验模拟得出,双层堤基发生管涌破坏后砂层破坏位置主要位于顶部,并与上覆黏土层的破坏过程
相互影响三
防渗墙作为有效的防渗加固工程被广泛应用,其中悬挂式防渗墙相较于半封闭和全封闭式防渗墙而言防渗效果并不显著,但对险情的扩展有一定的控制作用[9]三从生态角度考虑,悬挂式防渗墙不影响内外水力联系,有效避免了对下游生态环境的不利影响[10]三对于实际工程的一些深厚覆盖层,在现有技术的限制下防渗墙的插入深度通常不能做成封
闭式,因此对悬挂式防渗墙的研究仍有很大的现实意义三张家发等[11]通过对砂槽试验进行数值模拟进一步验证了悬挂式防渗墙的贯入深度对堤防安全有一定改善三王保田等[12]对上层为低液限黏土二下层为低液限粉土的二元结构堤基进行了渗流模拟试验,论证了悬挂式防渗墙有阻滞其渗透变形发展的四
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