| 土工膜-防渗墙-弱透水层联合防渗的有效性分析 |
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| 引用本文： | 王正成.土工膜-防渗墙-弱透水层联合防渗的有效性分析[J].地质与勘探,2020,56(3):580-589. |
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| 作者姓名： | 王正成 |
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| 作者单位： | 重庆三峡学院土木工程学院，重庆； 武汉大学水利水电学院，湖北武汉 |
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| 基金项目： | 国家自然科学基金项目（41602367）、重庆市科委基础与前沿研究计划项目（cstc2018jcyjA、cstc2019jcyj-msxm1330）和重庆市教委科学技术研究项目（KJQN201901209、KJQN201901209、KJQN201901240）联合资助 |
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| 摘 要： | 深厚覆盖层坝基往往都是强弱互层结构,坝基中存在弱透水层。弱透水层既是隔水层又是软弱夹层,是否利用其作为控渗依托层关系到工程难度、进度及成本。绝大多数工程都将全封闭式防渗体作为控渗首选方案,保守的设计理念导致采用半封闭式防渗体控渗的工程少之又少。西藏多布水电站采用土工膜-防渗墙-弱透水层三位一体半封闭式联合防渗体,在国内外少见,具有一定代表性,其防渗效果具有重要的参考价值和借鉴意义。本文基于详细的地质构造资料,以非饱和土体渗流、比奥固结理论和土体的非线性流变理论为基础,考虑土体水力学及土力学参数随双场耦合的动态变化关系,借助ADINA建立流固耦合模型,全方位分析多布水电站的渗流场、应力场,以及弱透水层的承载力和液化性。研究表明:土工膜-防渗墙-弱透水层三位一体半封闭式防渗体能有效降低渗透速度、渗流量和抑制渗透坡降,各渗流参量满足控渗要求;大坝及防渗墙的水平位移、沉降和应力相对悬挂式防渗体有一定增大,需提高防渗墙的强度。弱透水层是防渗体系中最重要的部分,经分析弱透水层承载力满足要求,且不会发生液化。对比分析三种防渗体系,多布水电站现采取的土工膜-防渗墙-弱透水层三位一体半封闭式联合防渗体是最佳方案,可减小防渗墙深度近193m。该研究成果对类似工程具有重要的参考价值和借鉴意义。
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| 关 键 词： | 深厚覆盖层 土工膜 防渗墙 弱透水层 半封闭式联合防渗体 多布水电站 西藏 |
| 收稿时间： | 2018/4/26 0:00:00 |
| 修稿时间： | 2019/10/22 0:00:00 |
Effectiveness of joint leakage control by using the trinity of geomembrane-cutoff wall-aquitard |
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| Wang Zhengcheng.Effectiveness of joint leakage control by using the trinity of geomembrane-cutoff wall-aquitard[J].Geology and Prospecting,2020,56(3):580-589. |
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| Authors: | Wang Zhengcheng |
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| Institution: | College of Civil Engineering, Chongqing Three Gorges University, Chongqing; Institute of Water Conservancy and Hydroelectric Power, Wuhan University, Wuhan, Hubei |
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| Abstract: | The Deep overburden dam foundation is usually a interbed structure of alternating strong and weak media, in which there exist aquitard that acts as both aquifuge and weak intercalation. Whether such beds can be used as base layer of seepage control will influence the cost and process of the project. In most cases to date, the totally enclosed impervious body is the preferred scheme of seepage control. Such a conservative design concept leads to the rare application of the semi-closed impervious body. An exception is the Duobu hydropower station in Tibet at which a semi-closed seepage-control system is employed, which is trinity of geomembrane-cutoff wall-aquitard, a representative case, and its anti-seepage effect has important reference value and significance. This paper builds on detailed geological structure data and the theories of unsaturated soil seepage, Biot consolidation and nonlinear rheology of soil. Considering the double-field coupling dynamic relationship of soil hydraulics and soil mechanics parameters, the software ADINA is used to establish a model of fluid-solid coupling for full analysis of the Duobu hydropower station of the seepage and stress fields around the Duobu hydropower station, focusing on bearing capacity and liquefaction of aquitard. Research shows that the trinity of the geomembrane, cutoff wall and aquitard as a semi-enclosed type of impervious wall can effectively reduce the seepage speed and amount and restrain seepage gradients. All seepage parameters meet requirements of control. While the horizontal displacement, settlement and stress of the dam and cut-off wall relative to the suspended impervious body will be increased to some extent, so it needs to enhance strength of the cut-off wall. The aquitard is the most important part of the anti-seepage system, of which the bearing capacity of meets requirement and no liquefaction will occur. Comparison of three seepage control systems shows that the trinity of the geomembrane-cutt-off wall-aquitard of semi-enclosed type of the impervious wall used at the Duobu hydropower station is the best scheme, which can reduce the depth of cut-off wall by nearly 193m. These research results would shed light on seepage control in similar projects. |
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| Keywords: | deep overburden layer geomembrane cut-off wall aquitard semi-closed anti-seepage system Duobu hydropower station |
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